Aims

Using data from the Hip Fracture Evaluation with Alternatives of Total Hip Arthroplasty versus Hemiarthroplasty (HEALTH) trial, we sought to determine if a difference in functional outcomes exists between monopolar and bipolar hemiarthroplasty (HA).

Aims

The aim of this study was to explore the functional results in a fitter subgroup of participants in the Hip Fracture Evaluation with Alternatives of Total Hip Arthroplasty versus Hemiarthroplasty (HEALTH) trial to determine whether there was an advantage of total hip arthroplasty (THA) versus hemiarthroplasty (HA) in this population.

Aims

To evaluate the impact of negative pressure wound therapy (NPWT) on the odds of having deep infections and health-related quality of life (HRQoL) following open fractures.

Aims

This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads.

Many studies report the incidence and prevalence of surgical site infections (SSIs) following open fractures; however, there is limited information on the treatment and subsequent outcomes of superficial SSIs in open fracture patients. There is also a lack of clinical studies describing the prognostic factors that are associated with failure of antibiotic treatment (non-operative) for superficial SSI. To address this gap, we used data from the FLOW (Fluid Lavage in Open Fracture Wounds) trial to determine how successful antibiotic treatment was for superficial SSIs and to identify prognostic factors that could be predictive of antibiotic treatment failure.

This is a secondary analysis of the FLOW trial dataset. The FLOW trial included 2,445 operatively managed open fracture patients. FLOW participants who had a non-operatively managed superficial SSI diagnosed in the 12 months post-fracture were included in this analysis. Participants were grouped into two categories: 1) participants whose superficial SSI resolved with antibiotics alone and 2) participants whose SSI did not resolve with antibiotics alone (defined as requiring surgical management or SSI being unresolved at final follow-up (12-months post-fracture for the FLOW trial)). Antibiotic treatment success and the date when this occurred was defined by the treating surgeon. A logistic binary regression analysis was conducted to identify factors associated with superficial SSI antibiotic success. Based on biologic rationale and previous literature, a priori we identified 13 (corresponding to 14 levels) potential factors to be included in the regression model.

Superficial SSIs were diagnosed in168 participants within 12 months of their fracture. Of these, 139 (82.7%) had their superficial SSI treated with antibiotics alone. The antibiotic treatment was successful in resolving the superficial SSI in 97 participants (69.8%) and unsuccessful in resolving the SSI in 42 participants (30.2%). We found that superficial SSIs that were diagnosed later in follow-up were associated with failure of treatment with antibiotic alone (Odds ratio 1.05 for every week in diagnosis delay, 95% Confidence Interval 1.004–1.099; p=0.03). Age, sex, fracture severity, fracture pattern, wound size, time from injury to initial surgical irrigation and debridement were not associated with antibiotic treatment failure.

Our secondary analysis of prospectively collected FLOW data found antibiotics alone resolved superficial SSIs in 69.8% of patients diagnosed with superficial SSIs. We also found that superficial SSIs that were diagnosed earlier in follow-up were associated with successful treatment with antibiotics alone. This suggests that if superficial SSIs are diagnosed and treated promptly, there is a higher probability that they will resolve with antibiotic treatment.

The primary objectives of this study were to: 1) identify risk factors for subsequent surgery following initial treatment of proximal humerus fractures, stratified by initial treatment type; 2) generate risk prediction tools to predict subsequent shoulder surgery following initial treatment; and 3) internally validate the discriminative ability of each tool.

We identified patients ≥ 50 years with a diagnosis of proximal humerus fracture from 2004 to 2015 using linkable health datasets in Ontario, Canada. We used procedural and fee codes within 30 days of the index fracture to classify patients into treatment groups: 1) surgical fixation; 2) shoulder replacement; and 3) conservative. We used intervention and diagnosis codes to identify all instances of complication-related subsequent shoulder surgery following initial treatment within two years post fracture. We developed logistic regression models for randomly selected two thirds of each treatment group to evaluate the association of patient, fracture, surgical, and hospital variables on the odds of subsequent shoulder surgery following initial treatment. We used regression coefficients to compute points associated with each of the variables within each category, and calculated the risk associated with each point total using the regression equation. We used the final third of each cohort to evaluate the discriminative ability of the developed risk tools (via the continuous point total and a dichotomous point cut-off value for “higher” vs. “lower” risk determined by Receiver Operating Curves) using c-statistics.

We identified 20,897 patients with proximal humerus fractures that fit our inclusion criteria for analysis, 2,414 treated with fixation, 1,065 treated with replacement, and 17,418 treated conservatively. The proportions of patients who underwent subsequent shoulder surgery within two years were 13.8%, 5.1%, and 1.3%, for fixation, replacement, and conservative groups, respectively. Predictors of reoperation following fixation included the use of a bone graft, and fixation with a nail or wire vs. a plate. The only significant predictor of reoperation following replacement was poor bone quality. The only predictor of subsequent shoulder surgery following conservative treatment was more comorbidities while patients aged 70+, and those discharged home following initial presentation (vs. admitted or transferred to another facility) had lower odds of subsequent shoulder surgery. The risk tools developed were able to discriminate between patients who did or did not undergo subsequent shoulder surgery in the derivation cohorts with c-statistics of 0.75–0.88 (continuous point total), and 0.82–0.88 (dichotomous cut-off), and 0.53–0.78 (continuous point total) and 0.51–0.79 (dichotomous cut-off) in the validation cohorts.

Our results present potential factors associated with subsequent shoulder surgery following initial treatment of proximal humerus fractures, stratified by treatment type. Our developed risk tools showed good to strong discriminative ability in both the derivation and validation cohorts for patients treated with fixation, and conservatively. This indicates that the tools may be useful for clinicians and researchers. Future research is required to develop risk tools that incorporate clinical variables such as functional demands.

Displaced femoral neck fractures can have devastating impacts on quality of life and patient function. Evidence for optimal surgical approach is far from definitive. The Hip Fracture Evaluation with Alternatives of Total Hip Arthroplasty versus Hemi-Arthroplasty (HEALTH) trial aimed to evaluate unplanned secondary procedures following total hip arthroplasty (THA) versus hemi-arthroplasty (HA) within two years of initial surgery for displaced femoral neck fractures. Secondary objectives evaluated differences in patient function, health-related quality of life, mortality, and hip-related complications HEALTH is a large randomized controlled trial that included 1,495 patients across 81 centers in 10 countries. Patients aged 50 years or older with displaced femoral neck fractures received either THA or HA. Participants were followed for 24 months post-fracture and a Central Adjudication Committee adjudicated fracture eligibility, technical placement of prosthesis, additional surgical procedures, hip-related complications, and mortality. The primary analyses were a Cox proportional hazards model with time to the primary study endpoint as the outcome and THA versus HA as the independent variable. Using multi-level linear models with three levels (centre, patient, and time), with patient and centre entered as random effects, the effect of THA versus HA on quality of life (Short Form-12 (SF-12) and EQ-5D), function (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)), and mobility (Timed Up and Go Test (TUG)) were estimated separately.

The majority of patients were female (70.1%), 70 years of age or older (80.2%), and able to ambulate without the aid of an assistive device before their fracture (74.4%), and the injury in the majority of the patients was a subcapital femoral neck fracture (61.9%). The primary end point occurred in 57 of 718 patients (7.9%) who were randomly assigned to THA and 60 of 723 patients (8.3%) who were randomly assigned to HA (hazard ratio, 0.95; 95% confidence interval [CI], 0.64 to 1.40; p=0.79). Hip instability or dislocation occurred in 34 patients (4.7%) assigned to total hip arthroplasty and 17 patients (2.4%) assigned to hemi- arthroplasty (hazard ratio, 2.00; 99% CI, 0.97 to 4.09). Function, as measured with the total WOMAC total score, pain score, stiffness score, and function score, modestly favored THA over HA. Mortality was similar in the two treatment groups (14.3% among the patients assigned to THA and 13.1% among those assigned to HA, p=0.48). Serious adverse events occurred in 300 patients (41.8%) assigned to THA and in 265 patients (36.7%) assigned to HA.

Among independently ambulating patients with displaced femoral neck fractures, the incidence of secondary procedures did not differ significantly between patients who were randomly assigned to undergo THA and those who were assigned to undergo HA, and THA provided a clinically unimportant improvement over HA in function and quality of life over 24 months.

Unstable chest wall injuries have high rates of mortality and morbidity. These injuries can lead to respiratory dysfunction, and are associated with high rates of pneumonia, sepsis, prolonged ICU stays, and increased health care costs. Numerous studies have demonstrated improved outcomes with surgical fixation compared to non-operative treatment. However, an adequately powered multi-centre randomized controlled study using modern fixation techniques has been lacking.

We present a multi-centred, prospective, randomized controlled trial comparing surgical fixation of acute, unstable chest wall injuries with the current standard of non-operative management. Patients aged 16–85 with a flail chest (3 or more consecutive, segmental, displaced rib fractures), or severe deformity of the chest wall, were recruited from multiple trauma centers across North America. Exclusion criteria included: severe pulmonary contusion, severe head trauma, randomization>72 hours from injury, inability to perform surgical fixation within 96 hours from injury (in those randomized to surgery), fractures of the floating ribs, or fractures adjacent to the spine not amendable to surgical fixation. Patients were seen in follow-up for one year. The primary outcome was days free from mechanical ventilation in the first 28 days following injury. Secondary outcomes were days in ICU, rates of pneumonia, sepsis, need for tracheostomy, mortality, general health outcomes, pulmonary function testing, and other complications of treatment. A sample size of 206 was required to detect a difference of 2 ventilator-free days between the two groups, using a 2-tailed alpha error of 0.05 and a power of 0.80.

A total of 207 patients were recruited from 15 sites across Canada and USA, from 2011–2018. Ninety-nine patients were randomized to non-operative treatment, and 108 were randomized to surgical fixation. Overall, the mean age was 53 years, and 75% of patients were male, with 25% females. The commonest mechanisms of injury were: motor vehicle collisions (34%), falls (20%), motorcycle collisions (14%), and pedestrian injuries (11%). The mean injury severity score (ISS) at admission was 26, and patients had a mean of 10 rib fractures. Eighty-nine percent of patients had pneumothorax, 76% had haemothorax, and 54% had pulmonary contusion. There were no differences between the two groups in terms of demographics. The final results will be available and presented at the COA meeting in Halifax.

This is the largest randomized controlled trial to date, comparing surgical fixation to non-operative treatment of unstable chest wall and flail chest injuries. The results of this study will shed light on the best treatment options for patients with such injuries, help understand outcomes, and guide treatment. The final results will be available and presented at the COA meeting in Halifax.

Aims

Using tibial shaft fracture participants from a large, multicentre randomized controlled trial, we investigated if patient and surgical factors were associated with health-related quality of life (HRQoL) at one year post-surgery.

Aims

The purpose of this study was to: review the efficacy of the induced membrane technique (IMT), also known as the Masquelet technique; and investigate the relationship between patient factors and technique variations on the outcomes of the IMT.

This study was designed to compare length of hospital stay, and 30-day major and minor complications between patients undergoing total knee arthroplasty (TKA) with general anesthesia, to those undergoing TKA with spinal or epidural anesthesia with or without regional nerve blocks.

Patients 18 years and older undergoing TKA between the years of 2005 and 2016 were identified from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP). Patient demographics, anesthesia type, length of operation and hospital stay, as well as 30-day major and minor complications were collected from the database. Patients with “primary anesthesia technique” codes for either spinal or epidural anesthesia along with “other anesthesia technique” codes for regional anesthesia were assumed to have been given a regional nerve block. Chi square tests, and analysis of variance were utilized to evaluate unadjusted differences in demographics and outcomes between anesthesia types. Multivariable regression was utilized to compare outcomes (length of stay and complications) between anesthesia types, while adjusting for age, American Society of Anesthesiologist (ASA) class, comorbidities, sex, steroid/immunosuppressant use, body mass index (BMI), diabetes, length of operation and smoking status.

A total of 214,665 TKA patients were identified (average age 67 ± 10 years). Of these, 257 (0.12%) underwent epidural anesthesia with a nerve block (EB), while 2,318 (1.08%) underwent epidural anesthesia with no block (E), 14,468 (1.08%) underwent spinal anesthesia with a block (SB), and 85,243 (39.7%) underwent spinal anesthesia with no block (S), and 112,377 (52.4%) underwent general anesthesia (G).

The unadjusted length of stay (LOS) was significantly longer in the E group (3.67 ± 5 days) compared to the G group (3.1 ± 3.9 days), while the unadjusted LOS was significantly shorter in the EB group (2.6 ± 1.2), and both SB and S groups (2.6 ± 3 and 2.9 ± 3, respectively), compared to the G group p < 0 .001. Following covariable adjustment, anesthesia type remained an independent predictor of length of stay. Compared to the G group, patients in the E group stayed 0.56 days longer (95% Confidence interval [95%CI] 0.42 – 0.71 days), while patients in the SB were discharged 0.28 days (95%CI 0.21 – 0.35 days) earlier, and those in the S group were discharged 0.06 days earlier (95%CI 0.02–0.09), (p < 0 .0001).

While the unadjusted rates of major complications were not significantly different between groups, the unadjusted rates of minor complications were higher in the E, EB, and G groups compared to the S and SB groups. Following covariable adjustment, there were no differences between groups in the risk of minor complications.

In conclusion, these data indicate that anesthesia type following TKA is associated with length of hospital stay, but not with 30-day complications. After adjusting for relevant covariables, patients who received epidural anesthesia without a nerve block for TKA were discharged later, while patients who received spinal anesthesia, both with and without a nerve block for TKA were discharged earlier, compared to patients who received general anesthesia for TKA.

This study was designed to compare atypical hip fractures with a matched cohort of standard hip fractures to evaluate the difference in outcomes.

Patients from the American College of Surgeons National Surgical Quality Improvement Program's (NSQIP) targeted hip fracture data file (containing a more comprehensive set of variables collected on 9,390 specially targeted hip fracture patients, including the differentiation of atypical from standard hip fractures) were merged with the standard 2016 NSQIP data file. Atypical hip fracture patients aged 18 years and older in 2016 were identified via the targeted hip fracture data file and matched to two standard hip fracture controls by age, sex, and fracture location. Patient demographics, length of hospital stay, 30-day mortality, major and minor complications, and other hip-specific variables were identified from the database. Binary outcomes were compared using the McNemar's test for paired groups, and continuous outcomes were compared using a paired t-test.

Ninety-five atypical hip fractures were identified, and compared to 190 age, sex, and fracture location matched standard hip fracture controls. There was no statistical difference in body mass index (BMI), race, ASA score, smoking status, timing of fixation, or functional status between the two groups (P>0.05). Thirty-day mortality was significantly higher in the atypical hip fracture group (atypical 7.36%, standard 2.11% p

This is the first study, to our knowledge, that demonstrates an increase in the rate of mortality in atypical hip fractures. Comparing atypical hip fractures with a matched cohort of standard hip fractures revealed a significantly greater 30-day mortality rate with an odds ratio of 3.62 in atypical hip fractures (95% CI 1.03–12.68). Prospective, clinical studies are recommended to further investigate these findings.

Tibial cut is a crucial step in ensuring adequate and appropriate proximal tibial resection for mechanical orientation and axis in total knee replacement. We evolved the concept and technique of Condylar Differential for planned tibial cuts in conventional total knee replacement, which accounts for individual variations and reflects individual mechanical orientation and alignment.

We used Condylar Differential in 37 consecutive total knee replacements including valgus knees and severe advanced osteoarthritis. First a vertical line is drawn on digital weight bearing anteroposterior radiograph for mechanical axis of tibia. Then a horizontal line is drawn across and perpendicular to the mechanical axis. The distances between the horizontal line and the lowest reproducible points of articular surfaces of medial and lateral tibial condyles respectively are measured. The difference between two measurements obviously represents Condylar Differential. Condylar Differential, adjusted to the nearest millimetre, is maintained in executing tibial cuts, successively if necessary.

Condylar Differential measurement showed a very wide variation, ranging from 8–6 (2 mm) to 10-0 (10 mm). We found that prior measurement of Condylar Differential is a simple, consistent and effective estimate and individualises the tibial cut for optimal templating of tibia. We encountered no problems, adopting this technique, in our series.

Condylar Differential contributes to optimal individualised tibial cut in conventional total knee replacement and is a useful alternative to computer navigated option with comparable accuracy in this respect. While we used the technique in digitised radiographs, this technique can also be applied to plain films, allowing for magnification.

Background

Mechanics and kinematics of the knee following total knee replacement are related to the mechanics and kinematics of the normal knee. Restoration of neutral alignment is an important factor affecting the long-term results of total knee replacement. Tibial cut is a vital and crucial step in ensuring adequate and appropriate proximal tibial resection, which is essential for mechanical orientation and axis in total knee replacement. Tibial cut must be individually reliable, reproducible, consistent and an accurate predictor of individual anatomical measurements. Conventional tibial cuts of tibia with fixed measurements cannot account for individual variations. While computer navigated total knee replacement serves as a medium to achieve this objective, the technology is not universally applicable for differing reasons. Therefore we evolved the concept and technique of Condylar Differential for planned tibial cuts in conventional total knee replacement, which accounts for individual variations and reflects the individual mechanical orientation and alignment.

Introduction

Previous studies have indicated that prolonged surgical time may lead to higher rates of infection following total hip arthroplasty (THA). The purpose of this study was to evaluate the influence of surgical time on 30-day complications following THA and to determine if there was a time interval associated with worse outcomes.

Introduction

This study was designed to evaluate the effect of discharge timing on 30-day major and minor complications in patients undergoing total knee arthroplasty (TKA) while adjusting for other variables.

Aims

The Fluid Lavage in Open Fracture Wounds (FLOW) trial was a multicentre, blinded, randomized controlled trial that used a 2 × 3 factorial design to evaluate the effect of irrigation solution (soap versus normal saline) and irrigation pressure (very low versus low versus high) on health-related quality of life (HRQL) in patients with open fractures. In this study, we used this dataset to ascertain whether these factors affect whether HRQL returns to pre-injury levels at 12-months post-injury.

Proximal humerus fractures are a common fragility fracture in older adults. A variety of treatment options exist, yet longer term outcomes of newer surgical treatments have not been extensively researched. Additionally, intermediate term outcomes following both surgical and non-surgical initial treatment of these injuries have not been evaluated at a population level. The purpose of this study was to utilise administrative data from Ontario, Canada to evaluate intermediate term outcomes following initial treatment of proximal humerus fractures.

We used data from the Canadian Institute for Health Information to identify all patients aged 50 and older who presented to an ambulatory care facility with a “main diagnosis” of proximal humerus fracture from April 1, 2004 to March 31, 2013. Intervention codes from the Discharge Abstract Database were used to categorise patients into fixation, replacement, reduction or non-surgically treated groups. We used intervention codes to identify instances of complication-related operations following initial treatment (including fixation, replacement, hardware removal, rotator cuff repair and irrigation and debridement [I&D]) at one year post initial treatment.

The majority of patients (28,369, 86.6%, 95% confidence interval [95% CI] 86.2–87.0%) were initially treated non-surgically, while 2835 (8.7%, 95% CI 8.4–9.0%) underwent initial fixation, 1280 (3.9%, 95% CI 3.7–4.1%) received primary joint replacement, and 276 (0.8%, 95% CI 0.8–1.0%) were initially treated with a reduction procedure. In the year following the initial treatment period, 127 (0.4%, 95%CI 0.4–0.5%) non-surgically treated patients underwent a replacement surgery, 292 (1.0%, 95%CI 0.9–1.2%) underwent fixation, and 12 (0.04%, 95% CI 0.02–0.07%) underwent a reduction procedure. Of the 2835 patients who received initial fixation, 57 (2.0%, 95% CI 1.6–2.6%) returned for a shoulder replacement, 80 received secondary fixation (2.8%, 95% CI 2.3–3.5%), 57 (2.0%, 95%CI 1.6–2.6%) underwent rotator cuff repair, 300 (10.6%, 95% CI 9.5–11.8%) had their implants removed, and 16 (0.6%, 95% CI 0.4–0.9%) returned for I&D. Of the 1280 patients who underwent initial replacement surgeries, 30 (2.3%, 95% CI 1.7–3.3%) returned for a secondary replacement, nine (0.7%, 95% CI 0.4–1.3%) underwent rotator cuff repair, and seven (0.6%, 95% CI 0.3–1.1%) had their implant removed. In the group who received initial reduction, eight (2.9%, 95% CI 1.5–5.6%) underwent a fixation procedure, six (2.2%, 95% CI 1.0–4.7%) received replacement surgeries, and five (1.8%, 95% CI 0.8–4.2%) each received rotator cuff repair and I&D in the year following initial treatment.

The majority of proximal humerus fractures in patients 50 and older in Ontario, Canada are treated non-surgically. Complication-related operations in the year following initial non-operative treatment are relatively low. The most commonly observed procedure following initial fixation surgery is hardware removal.

Proximal femur fractures are increasing in prevalence, with femoral neck (FN) and intertrochanteric (IT) fractures representing the majority of these injuries. The salvage procedure for failed open reduction internal fixation (ORIF) is often a conversion to total hip arthroplasty (THA). The use of THA for failed ORIF improves pain and function, however the procedure is more challenging. The aim of this study was to investigate the clinical and radiographic outcomes in patients who have undergone THA after ORIF.

This retrospective case-control study compared patients who underwent THA after failed ORIF to a matched cohort undergoing primary THA for non-traumatic osteoarthritis. From 2004 to 2014, 40 patients were identified. The matched cohort was matched for date of operation, age, gender, and type of implant. Preoperative, intraoperative, and postoperative data were collected and statistical analysis was performed.

The cohort of patients with a salvage THA included 18 male and 22 female patients with a mean age of 73 years and mean follow up of 3.1 years. Those with failed fixation included 12 IT fractures and 28 FN fractures. The mean time between ORIF and THA was 2.1 years for IT fractures and 8.5 years for FN fractures (p=0.03). The failed fixation group had longer procedures, greater drop in hemoglobin, and greater blood transfusion rate (p<0.05). There was one revision and one dislocation in the failed fixation group with no revisions or dislocations in the primary THA group. Length of admission, medical complications, and functional outcome as assessed with a standardised hip score and were found not to be statistically different between the groups.

Salvage THA for failed initial fixation of proximal femur fractures yields comparable clinical results to primary THA with an increased operative time, blood loss, and blood transfusion rate.

Modular total hip arthroplasty (MTHA) stems were introduced in order to provide increased intra-operative flexibility for restoring hip biomechanics, improving stability and potentially reducing revision risk. However, the additional interface at the neck-body junction provides another location for corrosion or mechanical failure of the stem. To delineate the mid term revision risk of MTHA stems, we examined data from the Canadian Joint Replacement Registry (CJRR) at the Canadian Institute for Health Information (CIHI).

Kinectiv, Profemur and Rejuvenate modular stems were identified from CJRR records submitted between 2004 and 2014. Revision status was determined by examining the discharge abstract database (DAD) also housed by CIHI, which collects information on all revisions, regardless of whether the procedure was submitted to CJRR.

A total of 2446 modular stems were identified with a mean follow up of 4.2 years (range 0 to 10). Their usage peaked in 2012 (the first year of mandatory CJRR form submission for BC, ON and MB), and dropped rapidly thereafter. A total of 155 (6.3%) were revised. This consisted of 5/301 Kinectiv (1.7%), 141/2050 ProFemur (6.9%), and 9/96 Rejuvenate (9.4%) stems. As a group, this falls below the National Institute for Clinical Excellence (NICE) guidelines of 95% survival at 10 years.

While MTHA stems were introduced to improve outcomes and reduce revision risk, our findings of a 6.3% revision risk at a mean follow up of 4.2 years does not appear to support this.

The purpose of this study was to examine the utility of the acetabular component introducer as a tool to intra-operatively predict implant inclination in total hip arthroplasty. This study investigated (1) the correlation between intra-operative photographic assessment of cup inclination using the acetabular introducer and that measured on post-operative radiograph; and (2) the accuracy of intra-operative prediction of abduction angle.

For this study, we prospectively recruited 56 patients scheduled to receive primary hip arthroplasty from one of two senior surgeons. During the procedure, the lead surgeon provided a prediction of the abduction angle based on the alignment of the impactor attached to the cup in its final seated position. A standardized anteroposterior (AP) photograph was then taken of the acetabular impactor in situ. Abduction angles were measured by two observers on the photographs and post-operative AP pelvis radiographs. Linear regression was used to determine the correlation between the angle of the guide measured on the photographs and the actual position of the implant measured on the radiograph. Descriptive statistics were further used to analyze the accuracy of the intra-operative prediction as compared with the abduction angle measured on the photographs.

Measurements of cup position made from post-operative radiographs were significantly correlated with the measurements as assessed by intra-operative photographs (r = 0.34, p = 0.00). Our findings demonstrate that radiological abduction angles tend to be greater than that assessed by intra-operative photographs by a mean of 5.6 degrees (SD = 6.6 degrees; 95% CI = 7.3 to 3.9 degrees). Conversely, surgeon prediction of cup inclination based on the acetabular introducer differed from the radiographic measurements by a mean of 6.8 degrees (SD = 8.7 degrees). There was good agreement between the two observers in both photographic and radiographic measurement (k = 0.95, k = 0.96, respectively).

In conclusion, we found that the intra-operative photographic assessment of acetabular cup inclination by acetabular impactor alignment tends to underestimate the abduction angle by a mean of approximately 5 degrees. In addition, intra-operative surgeon estimation of acetabular inclination did not appear accurate in this study demonstrating that cup position should rely on additional visual cues beyond that captured in the anteroposterior view of the cup introducer.

Introduction:

One method of femoral head preservation following avascular necrosis (AVN) is core decompression and Tantalum Rod insertion. There is, however, a published failure rate of up to 32% at 4 years. The purpose of the present study was to document the clinical and radiological outcome following Total Hip Arthroplasty (THA) subsequent to failed Tantalum Rod insertion.

Introduction:

Alignment of the initial femoral guidewire is critical in avoiding technical errors that may increase the risk of failure of the femoral component. A novel alternative to conventional instrumentation for femoral guidewire insertion is a computed tomography (CT) based alignment guide. The aim of this study was to assess the accuracy of femoral component alignment using a CT-based, patient specific femoral alignment guide.

Purpose:

The use of computer navigation has been shown to improve the accuracy of femoral component placement compared to conventional instrumentation in hip resurfacing. Whether exposure to computer navigation improves accuracy when the procedure is subsequently performed with conventional instrumentation without navigation has not been explored. We examinedwhether femoral component alignment utilizing a conventional jig improves following experience with the use of imageless computer navigation for hip resurfacing.

Introduction

There has been a paradigm shift in orthopaedic research, it is now recognized that the extent to which interventions really make a difference to a patient's overall life is indicated by measuring one's general health status. The primary aim of this study was to report how the methodology of current evidence in hip fracture research can improve if studies included patients with cognitive impairment.

The Study to Prospectively Evaluate Reamed Intramedullary Nails in Tibial Shaft Fractures (SPRINT) randomised 1,226 patients treated by intramedullary nailing to reamed versus unreamed groups. We aimed to determine if there was a difference in the number of patients requiring more than one reoperation between the groups.

We hypothesised there would be differences in the number of patients with more than one reoperation in the reamed versus unreamed groups and in patients with open fractures versus closed fractures.

We identified patients requiring more than one reoperation during the 12 m follow-up. We considered those that were reamed versus unreamed, open versus closed, and those with a reoperation planned post 12 m follow-up. We also compared patient and fracture characteristics.

We identified a total of 44 patients requiring two or more reoperations. No difference between the reamed and unreamed groups was found in the risk of having more than one reoperation. Patients with two or more reoperations were older (p=0.03), had a higher frequency of open fractures (p<0.001), and had higher energy mechanisms of injury (p<0.001). The first reoperation was in response to infection for 25 patients. 12 patients had additional reoperations planned after the 12 m follow-up.

A relatively small number of tibial shaft fracture patients required more than one reoperation. Further study is required to assess consequences of needing multiple reoperations in this high risk group.

Introduction

Nonunion is a common and costly fracture outcome. Intricate reciprocity between angiogenesis and osteogenesis means vascular cell-based therapy offers a novel approach to stimulating bone regeneration.

Implant alignment in knee arthroplasty has been identified as critical factor for a successful outcome. Human error during the registration process for imageless computer navigation knee arthroplasty directly affects component alignment. This cadaveric study aims to define the error in the registration of the landmarks and the resulting error in component alignment.

Five fresh frozen cadaveric limbs including the hemipelvis were used for the study. Five surgeons performed the registration process via a medial parapatellar approach five times. In order to identify the gold standard point, the soft tissues were stripped and the registration was repeated by the senior author. Errors are presented as mm or degrees from the gold standard registration.

The error range in the registration of the femoral centre in the coronal plane was 6.5mm laterally to 5.0mm medially (mean: −0.1, SD: 2.7). This resulted in a mechanical axis error of 5.2 degrees valgus to 2.9 degrees varus (mean: 0.1, SD: 1.1). In the sagittal plane this error was between −1.8 degrees (extension) and 2.7 degrees (flexion). The error in the calculation of the tibial mechanical axis ranged from −1.0 (valgus) to 2.3 (varus) degrees in the coronal plane and −3.2 degrees of extension to 1.3 degrees of flexion. Finally the error in calculating the transepicondylar axis was −11.2 to 6.3 degrees of internal rotation (mean: −3.2, SD: 3.9).

The error in the registration process of the anatomical landmarks can result in significant malalignment of the components. The error range for the mechanical axis of the femur alone can exceed the 3 degree margin that has been previously been associated with implant longevity. The technique during the registration process is of paramount importance for image free computer navigation. Future research should be directed towards simplifying this process and minimizing the effect of human error.

Introduction

Hip resurfacing arthroplasty (HRA) has seen a recent revival with third generation Metal-on-Metal prostheses and is now widely in use. However, safety and effectiveness of hip resurfacing are still questioned. We systematically reviewed peer-reviewed literature on hip resurfacing arthroplasty to evaluate implant survival and functional outcomes of hybrid Metal-on-Metal hip resurfacing Arthroplasty.

Background

Hip resurfacing arthroplasty (HRA) has seen a recent revival with third generation Metal-on-Metal prostheses and is now widely in use. However, safety and effectiveness of hip resurfacing are still questioned. We systematically reviewed peer-reviewed literature on hip resurfacing arthroplasty to address these issues.

This prospective randomised controlled trial aims to compare the clinical and radiological outcomes of ceramic on ceramic, cobalt chrome on ultra-high molecular weight polyethylene, and cobalt chrome on highly cross-linked polyethylene bearing surfaces at a minimum of five years.

One hundred and two primary total hip replacements were performed in ninety one patients between February 2003 and March 2005. All patients were younger than 65 (mean 52.7, 19–64). They were randomised to receive one of the three bearing surfaces. All patients had 28mm articulations with a Reflection uncemented acetabular component and a Synergy stem (Smith & Nephew, Memphis, Tennessee). Patients were followed up periodically up to at least sixty months following surgery. Outcome measures included WOMAC and SF12 scores. Radiological assessment included implant position, evidence of osteolysis and measurement of linear wear.

Ninety seven hip replacements in eighty seven patients were available for review at a minimum of five years. Two hips were revised (one for infection and one for periprosthetic fracture), leaving a total of ninety four hips available for final review. There were no differences in age, gender, body mass index, diagnosis, level of activity, and co-morbidities between the three groups. At a minimum of five years there were no statistical differences in the clinical outcomes using the WOMAC or SF12 scores. Three patients in the ceramic group reported squeaking. Radiological evaluation revealed mean annual wear rates in the ceramic group of 0.006mm/yr, standard polyethylene of 0.151mm/yr and highly cross linked polyethylene of 0.059mm/yr. ANOVA analysis revealed these differences in wear rates to be significant (p<0.0001).

In the mid term there are no differences in clinical outcome between ceramic on ceramic, cobalt chrome on ultra-high molecular weight polyethylene, and cobalt chrome on highly cross-linked polyethylene bearing surfaces in total hip arthroplasty. Ultra high molecular weight polyethylene has a significantly greater annual linear wear rate than highly cross-linked polyethylene.

To review prospectively collected data on patients undergoing primary total hip arthroplasty utilizing two different cementless acetabular components.

All patients undergoing primary total hip replacement surgery at our institution are entered prospectively into a database which includes history and physical examination, radiology, WOMAC and SF-36 scores. The patients are re-examined, re-x-rayed and re-scored at 3 months, 6 months and 1 year after surgery and yearly thereafter.

Using this database we are able to identify patients who have undergone total hip replacement using one of two geometric variants of the acetabular component. The first design is hemispherical and the second design has a peripheral rim expansion designed to increase initial press-fit stability.

Five hundred and twenty-seven consecutive primary total hip replacements were identified using either of the geometric variants of the acetabular component. Results at a mean of 7 years revealed a 95.6% survivorship with no significant difference between the two component designs with revision for aseptic loosening as the end point. Functional scores between the two groups of patients also demonstrated no statistically significant difference.

Radiologic assessment, however, showed a difference between the two designs. The hemispherical design which matches the reamer line-to-line had 80% complete osseointegration on final radiologic review while the second design with a peripheral rim expansion had only 57% complete osseointegration. This was statistically significant. The peripherally expanded components also had a greater number of screws inserted at the time of surgery, felt by us to be a reflection of initial surgeon dissatisfaction with component stability at the time of insertion of the component.

The difference in screw numbers was also statistically significant. This study demonstrates that a hemispherical design with line-to-line contact between the acetabular component surface and the acetabular bone is statistically superior in terms of bone ingrowth and probably statistically superior in terms of initial press-fit stability when compared to a peripherally expanded component.

Peripherally expanded components appear to offer no advantage over hemispherical components in terms of clinical outcome and are statistically inferior to hemispherical components in radiologic parameters at 7 years follow-up.

Purpose

To review prospectively collected data on patients undergoing primary total hip arthroplasty utilizing two different cementless acetabular components.

To review prospectively collected data on patients undergoing femoral revision arthroplasty for failed cemented or cementless primary stems.

Aim

This prospective randomised controlled trial aims to compare the clinical and radiological outcomes of ceramic on ceramic, cobalt chrome on ultra-high molecular weight polyethylene, and cobalt chrome on highly cross-linked polyethylene bearing surfaces at a minimum of five years.

We designed this study to determine the clinical evidence to support use of the five degree tibial extra-medullary cutting block over the zero degree cutting block.

We identified three groups of patients from the databases and clinical notes at St Michaels Hospital, Toronto. Group one were primary total knees performed using the five degree cutting block, group two were primary total knees performed using the zero degree cutting block and the third group were computer navigated primary total knees. Patients in all three groups were age and sex matched. The senior author advocating use of the five degree block aimed to obtain a five degree posterior slope. The senior author who advocated the use of computer navigation, or the traditional zero degree cutting block, aimed to obtain a three degree posterior slope. All operations were performed by residents or clinical fellows, under the supervision of the senior authors. Patient radiographs were assessed to obtain the optimal direct lateral view obtained and they were saved on a database. Two independent blinded researchers assessed the posterior slope using Siemens Magicweb Software Version VA42C_0206. Two methods were used and the results averaged. The average posterior slope for the navigated total knee replacements was 0.1 degrees (−2 to 4). The average posterior slope for the five degree cutting block was 5.2 degrees (−2 to 16). The average posterior slope for the zero degree block was 3.79 degrees (−2 to 13). Computer navigated knee arthroplasty patients had significantly less variation in outlier measurements compared to the traditionally jigged arthroplasty patients. They were however, less accurate. The five degree cutting block tended to provide a more consistent posterior slope angle, but both the five degree and zero degree cutting blocks had variability in outliers. Computer Navigated Total Knee replacement provides a more consistent and reproducible tibial cut with less variability in alignment than extra-medullary jigs. The traditional five degree cutting block tended to provide a more reliable five degree posterior slope than the zero degree block, but was still subject to outliers.

The aim of this study was to determine the mid-term survival and functional outcomes of the Scorpio Total Stabilised Revision Knee prosthesis.

Sixty seven prostheses were implanted between November 2001 and April 2008. 42 females and 23 males. Average patient age was 67.9 (37-89). Outcomes were assessed with WOMAC (Western Ontario and McMaster Universities Osteoarthritis index), Knee Society Scores, Short Form-8 scores, patient satisfaction and radiological review. Average follow-up was over 3 years (8-93mths) with 95% follow-up.

One patient died post operatively and 4 patients from 18 months to 5 years post-operatively. Average body mass index was 32.9 (21.5- 55.1). 65% (42 patients) of patients operated on had a Body Mass Index of greater than 30. 48 patients were ASA 3 or greater.

Thirteen second stage revision arthroplasties were performed after treatment for infected arthroplasty surgery. Twenty six prostheses were revised for aseptic loosening. Eight prostheses were revised for stiffness and 9 for worn polyethylene inserts. Five prostheses were revised for symptomatic tibio-femoral instability/ dislocation and one for patello-femoral instability. Two revisions were performed for peri-prosthetic fractures and 2 for previously operated tibial plateau fractures.

Seven patients required tibial tubercle osteotomy and seven a rectus snip. Thirty one patients had greater than a 15mm polyethylene insert. The average KSS increased from 49 pre-operatively to 64 at 7.5 years. The average KS function score increased from 21 to 45. 68% (44) of patients had other significant joint involvement which affected daily function. 24% of patients were unsatisfied with the outcome. 89.5% of patients radiographs were assessed for loosening or subsidence. 51% of femoral components and 36% of tibial components had radiosclerotic lines. The surface area of each implant including the stem was measured on antero-posterior and lateral images. The degree of lucency was calculated as a percentage and in mm from the component.

Two prostheses (3%) were revised for deep infection, one (1.5%) for stiffness and one for aseptic loosening (1.5%). Complications included a popliteal artery injury, two superficial wound infections, and one patella tendon avulsion.

Survival rate for revision of prosthesis was 87% at 7.5 years and 90% excluding infection. Success of second stage revision arthroplasty after treatment of infection was 92%.

The purpose of this study was to evaluate 3 methods used to produce posterior tibial slope.

The purpose of this study was to evaluate total hip arthroplasty (THA) in the treatment of post-traumatic arthritis following acetabular fracture and to compare the long-term outcome of THA after previous open reduction and internal fixation (ORIF) or conservative treatment of the acetabular fracture.

Thirty-four patients (thirty-six hips) underwent total hip arthroplasty for arthritis resulting from acetabular fractures. There were twenty-six males (27 hips) and eight females (9 hips). The mean age at the time of hip arthroplasty was 49 years (range, 25-78 years). The mean follow-up was eight years and nine months (range, 4-17 years). The mean interval from fracture to arthroplasty was 7.5 years (range, 5 months-29 years). Two patients died of unrelated causes and two patients were lost to follow-up. Thirty patients (32 hips) were available for latest follow-up. Twenty-one hips had been previously treated by open reduction internal fixation and 11 hips had conservative treatment.

Sixteen patients achieved and maintained a good to excellent result over the course of the follow-up. There was no difference in improvement of mean Harris Hip Score between both groups (p>0.05). Ten out of 32 hips required revision; 9 acetabular components were revised because of aseptic loosening (3), osteolysis/excessive wear (4), instability (1) and infection (1) with a total revision rate of 28%. Eight patients needed acetabular revision alone, one femoral revision alone and one revision of both components. There was no significant difference in bone grafting, heterotopic bone formation, revision rate, operative time and blood loss between the two groups (p> 0.05).

Those patients initially treated conservatively had similar long term results compared to those treated primarily by open reduction internal fixation. At long term follow-up the main problem identified was osteolysis and acetabular wear.

We aimed to identify whether patients in lower socioeconomic groups had worse function prior to total knee arthroplasty and to establish whether these patients had worse post-operative outcome following total knee arthroplasty.

Data were obtained from the Kinemax outcome study, a prospective observational study of 974 patients undergoing primary total knee arthroplasty for osteoarthritis. The study was undertaken in thirteen centres, four in the United States, six in the United Kingdom, two in Australia and one in Canada. Pre-operative data were collected within six weeks of surgery and patients were followed for two years post-operatively. Pre-operative details of the patient's demographics, socioeconomic status (education and income), height, weight and co-morbid conditions were obtained. The WOMAC and SF-36 scores were also obtained. Multivariate regression was utilised to analyse the association between socioeconomic status and the patient's pre-operative scores and post-operative outcome. During the analysis, we were able to control for variables that have previously been shown to effect pre-operative scores and post-operative outcome.

Patients with a lower income had a significantly worse pre-operative WOMAC pain (p=0.021) and function score (p=0.039) than those with higher incomes. However, income did not have a significant impact on outcome except for WOMAC Pain at 12-months (p=0.014). At all the other post-operative assessment times, there was no correlation between income and WOMAC Pain and WOMAC Function. Level of education did not correlate with pre-operative scores or with outcome at any time during follow-up. This study demonstrates that across all four countries, patients with lower incomes appear to have a greater need for total knee arthroplasty. However, level of income and educational status did not appear to affect the final outcome following total knee arthroplasty. Patients with lower incomes appear able to compensate for their worse pre-operative score and obtain similar outcomes post-operatively.

Surgeons performing hip resurfacing ante-vert and translate the femoral component anterior to maximize head/neck offset and educe impingement. The anterior femoral neck is under tensile forces during gait similarly to the superior neck [6]. This study was esigned to determine the risk of femoral neck fracture after anterior or posterior notching of the femoral neck.

Method: Fortyseven 4th generation synthetic femora were implanted with Birmingham Hip Resurfacing pros-theses (Smith & Nephew Inc. emphis, USA). Implant preparation was performed using imageless computer navigation (VectorVision SR 1.0, BrainLAB, Grmany). The virtual prosthesis was initially planned for neutral version and translated anterior, or posterior, to create the notch. The femora were fixed in a single-leg stance and tested with axial compression using a mechanical testing machine. This method enabled comparison with previously published data. The synthetic femora were prepared in 8 experimental groups:2mm and 5mm anterior notches, 2mm and 5mm posterior notches, neutral alignment with no notching (control), 5mm superior notch, 5mm anterior notch tested with the femur in 25° flexion and 5mm posterior notch tested with the femur in 25° extension We tested the femora flexed at 25° flex-ion to simulate loading as seen during stair ascent. [3] The posterior 5mm notched femoral necks were tested in extension to simulate sporting activities like running. The results were compared to the control group in neutral alignment using a one-way ANOVA:

Results: Testing Group Mean load to failure Significance Neutral (Control) 4303.09 ± 911.04N Anterior 2mm 3926.62 ± 894.17N p=0.985 Anterior 5mm 3374.64 ± 345.65N p=0.379 Posterior 2mm 4208.09 ± 1079.81N p=1.0 Posterior 5mm 3988.07 ± 728.59N p=0.995 Superior 5mm 2423.07 ± 424.16N p=0.003 Anterior 5mm in 25° flexion 3048.11 ±509.24N p=0.087 Posterior 5mm in 25° extension 3104.61±592.67N p=0.117 Both the anterior 5mm notch tested in single-leg stance and anterior notch in flexion displayed lower compressive loads to failure (3374.64N and 3048.11N). The mean load to failure value for the posterior 5mm notches in extension was 3104.62N compared to 4303.09N for the control group. Our data suggests that anterior and posterior 2mm notches are not statistically significantly weaker in axial compression. The anterior 5mm notches tend towards significance in axial compression (p=0.38) and bordered significance in flexion (p=0.087). The 5mm posterior notches were not significantly weakened in axial compression (p=0.995), but tended towards significance in extension (p=0.117). The 5mm superior notch group was significantly weaker with axial compression supporting previous data published (p=0.003). We are currently assessing offset and other variables that may reduce data spread.

Conclusion: We conclude that anterior and posterior 2mm notching of the femoral neck has no clinical implications, however 5mm anterior notches may lead to fracture. The fracture is more likely to occur with stair ascent rather than normal walking. Posterior 5mm notches are not likely to fracture with normal gait, but may fracture with higher impact activities that promote weight bearing in extension. Hip resurfacing is commonly performed on active patients and ultimately 5mm notching in the anterior or posterior cortices has clinically important implications.

Oxidized Zirconium (Oxinium, Smith & Nephew, Inc., Memphis, TN) is a relatively new material that features an oxidized ceramic surface chemically bonded to a tough metallic substrate. This material has demonstrated the reduced polyethylene wear characteristics of a ceramic, without the increased risk of implant fracture. The purpose of the current investigation was to assess clinical outcomes following primary total hip arthroplasty with Oxinium versus Cobalt Chrome femoral heads.

One hundred uncemented primary total hip arthroplasty procedures were prospectively performed in 100 patients. There were 52 males and 48 females with mean age at the time of surgery of 51 years (SD 11, range, 19–76). Using a process of sealed envelope randomization, patients were divided into 2 groups. Each group contained fifty patients. Those in group 1 received an Oxinium femoral head (OX), while those in group 2 a cobalt-chrome femoral head (CC).

The current study reports clinical outcome measures for both the OX and CC groups at a minimum follow-up of 2 years postoperatively. At the time of latest follow-up, stem survival for both groups was 98%. There was a significant improvement in all clinical outcome scores between preoperative and 2 year postoperative time periods for both bearing groups (p< 0.003). There were no significant differences between bearing groups for any of the clinical outcome scores at final follow-up (p> 0.159). Mean Harris Hip Scores at 2 years postoperatively were 92 and 92.5 for OX and CC, respectively (range; 65–100 OX, 60–100 CC). For SF-12, both the Physical Component Summary Scale (PCS) and the Mental Component Summary Scale (MCS) are reported. Mean PCS scores at final follow-up were 45.2 and 49.21 for OX and CC (range; 27.1–56.7 OX, 26.3–61.8 CC). Mean MCS scores were 53.8 and 52.57 for OX and CC (range; 39.2–65.5 OX, 34.3–64 CC). Mean final WOMAC scores are reported as 84.9 and 87 for OX and CC, respectively.

The current data suggest that total hip arthroplasty utilizing Oxinium femoral heads is safe and effective. Additional follow-up of the current cohort will be performed in order to fully assess mid-to long-term clinical outcomes.

Posterior slope of the tibial component is an important factor in overall alignment of Total Knee Arthroplasty. The purpose of this study was to compare the accuracy and reproducibility of tibial bone cuts utilizing traditional extramedullary 0 degree and angled 5 degree cutting blocks, and computer aided navigation, in primary total knee arthroplasty.

We identified 3 groups of patients. Group one were primary total knees performed using an extramedullary 0 degree cutting block for posterior slope, group 2 were performed using an extramedullary 5 degree cutting block and the third group were performed with computer navigation. Patients in all 3 groups were age and sex matched. All operations were performed by residents or clinical fellows, under the supervision of the senior authors. Lateral digital radiographs were reviewed and posterior slope was determined in a standardized fashion. Two independent blinded researchers assessed the posterior slope using Siemens Magicweb software version VA42C_0206.

The average difference from the ideal posterior slope in navigated knees was lower than with non-navigated knees, however this was not significant (p=0.086). The average difference from the ideal posterior slope in computer navigated knees was 1.77 degrees (95% CI=1.28 to 2.26) compared to 2.37 degrees (95% CI=1.56 to 3.17) with the 5 degree cutting block and 2.70 degrees (95% CI=1.73 to 3.66) with the 0 degree block. No absolute significant difference was highlighted between the 3 groups using ANOVA testing (p=0.22).

All three techniques used to obtain ideal tibial slope were accurate. Accuracy was not increased by the use of computer navigation; however navigation resulted in less variation in outcome. The two jig based methods produced similar outcomes and either technique can be used successfully.

This study was designed to determine the risk of femoral neck fracture after anterior or posterior notching of the femoral neck. The anterior femoral neck is under tensile forces during gait similarly to the superior neck [6].

Method: Fortyseven 4th generation synthetic femora were implanted with Birmingham Hip Resurfacing pros-theses (Smith & Nephew Inc. Memphis, USA). Implant preparation was performed using imageless computer navigation (VectorVision SR 1.0, BrainLAB, Germany). The prosthesis was initially planned for neutral version and translated anterior, or posterior, to create a femoral neck notch. The femora were fixed in a single-leg stance and tested with axial compression. This method enabled comparison with previously published data. The synthetic femora were prepared in 8 experimental groups: 2mm and 5mm anterior notches, 2mm and 5mm posterior notches, neutral alignment with no notching (control), 5mm superior notch, 5mm anterior notch tested with the femur in 25° flexion and 5mm posterior notch tested with the femur in 25° extension

We tested the femora flexed at 25° flexion to simulate loading as seen during stair ascent. [3] The posterior 5mm notched femoral necks were tested in extension to simulate sporting activities like running. The results were compared to the control group in neutral alignment using a one- way ANOVA:

Results: Testing Group Mean load to failure Significance

Neutral (Control) 4303.09 ± 911.04N

The anterior 5mm notch tested in single-leg stance and anterior notch in flexion displayed lower compressive loads to failure (3374.64N and 3048.11N). The mean load to failure value for the posterior 5mm notches in extension was 3104.62N compared to 4303.09N for the control group.

Our data suggests that anterior and posterior 2mm notches are not significantly weaker in axial compression. The anterior 5mm notches was not significant in axial compression (p=0.38), but trended towards significance in flexion (p=0.087). A 5mm posterior notch was not significant. (p=0.995, p=0.117). The 5mm superior notch group was significantly weaker with axial compression supporting previous published data (p=0.003).

Conclusion: We conclude that anterior and posterior 2mm notching of the femoral neck has no clinical implications, however a 5mm anterior femoral neck notch may lead to fracture. The fracture is more likely to occur with stair ascent rather than normal walking given the reduction in strength noted after testing in flexion. Posterior 5mm notches are not likely to fracture. Hip resurfacing is commonly performed on active patients and 5mm notching of anterior cortex has clinically important implications.

Minimizing tip-apex distance has been shown to reduce clinical failure of sliding hip screws used to fix peritro-chanteric fractures. The purpose of this study was to determine if such a relationship exists for the position of the lag screw in the femoral head using a cephalomedullary device.

Methods: Thirty intact synthetic femur specimens (Model #3406, Pacific Research Laboratories, Vashon, WA) were potted into cement blocks distally for testing on an Instron 8874 (Instron, Canton, MA). A long cephalomedullary nail (Long Gamma 3 Nail, Stryker, Mahwah, NJ) was inserted into each of the femurs. An unstable four-part fracture was created, anatomically reduced, and repaired using one of 5 lag screw placements in the femoral head:

Superior (N=6),

Mechanical tests were repeated for axial, lateral and torsional stiffness. All specimens were radiographed in the anterioposterior and lateral planes and tip-apex (TAD) distance was calculated. A calcar referenced tip-apex distance (CalTAD) was also calculated.

ANOVA was used to compare means of the five treatment groups. Linear regression analysis was used to compare axial, lateral and torsional stiffness (dependant variables) to both TAD and CalTAD (independent variables).

Results: ANOVA testing proved that the mean axial (p< 0.01) and torsional stiffness (p< 0.01) between the 5 groups was significantly different, but lateral stiffness was not statistically different (p=0.494). Post hoc analysis showed that the inferior lag screw position provided significantly higher mean axial stiffness (568.14±66.9N/ mm) than superior (428.0±45.6N/mm; p< 0.01), anterior (443.2±45.4N/mm; p=0.02) and posterior (456.7±69.3N/ mm; p=0.04) lag screw positions. There was no significant difference in mean axial stiffness between inferior (568.14±66.9N/mm) and central (525.4±81.7N/mm) lag screw positions (p=0.77). Post hoc analysis revealed significantly less mean torsional stiffness for the superior lag screw position compared to other lag screw positions (p< 0.01 all 4 pairings). There were no significant correlations between TAD and axial (r=−0.33, p=0.08), lateral (r=−0.22, p=0.24) or torsional (r=0.08, p=0.69) stiffness. There were significant correlations between CalTAD and axial (r=−0.66, p< 0.01), lateral (r=−0.38, p=0.04) and torsional (r=−0.38, p=0.04) stiffness.

Discussion: Our results suggest that placement of the lag screw inferiorly in the femoral head when using a cephalomedullary nail to treat an unstable peritrochanteric fracture results in the stiffest construct in axial and torsional biomechanical testing. A simple radiographic measurement, CalTAD, provides an intraoperative method of determining optimal cephalomedullary nail lag screw position to achieve greatest construct stiffness.

The use of metal on polyethylene articulations was a key development in establishing total hip arthroplasty as a successful and reproducible treatment for end stage osteoarthritis. In order to ensure implant durability in relatively younger populations, there is a need for alternative, wear resistant bearing surfaces. Oxidized Zirconium (Oxinium, Smith & Nephew, Inc., Memphis, TN) is a relatively new material that features an oxidized ceramic surface chemically bonded to a tough metallic substrate. This material has demonstrated the reduced polyethylene wear characteristics of a ceramic, without the increased risk of implant fracture. The purpose of the current investigation was to assess early clinical outcomes following primary total hip arthroplasty with Oxinium versus Cobalt Chrome femoral heads.

One-hundred primary THA procedures were prospectively performed in 100 patients. There were 52 males and 48 females. Using a process of sealed envelope randomization, patients were divided into 2 groups. Group 1 consisted of fifty patients, each receiving primary THA implants with an Oxinium femoral head (OX). The mean age of each patient was 51 years (SD 10.8, Range 22–74) with 26 males and 24 females. Group 2 also consisted of 50 patients. Within this group again each patient received primary THA implants however with a cobalt-chrome femoral head (CC). Demographics were similar with mean age 51 years (SD 11.0, Range 19–76) and again 26 males and 24 females.

The current study reports clinical outcome measures for both the OX and CC groups at a minimum follow-up of 2 years postoperatively. At the time of latest follow-up, stem survival for both groups was 98%. There was a significant improvement in all clinical outcome scores between preoperative and 2 year postoperative time periods for both bearing groups (p< 0.003). There were no significant differences between bearing groups for any of the clinical outcome scores at final follow-up (p> 0.159). Mean Harris Hip Scores at 2 years postoperatively were 92 and 92.5 for OX and CC, respectively (range; 65–100 OX, 60–100 CC). For SF-12, both the Physical Component Summary Scale (PCS) and the Mental Component Summary Scale (MCS) are reported. Mean PCS scores at final follow-up were 45.2 and 49.21 for OX and CC (range; 27.1–56.7 OX, 26.3–61.8 CC). Mean MCS scores were 53.8 and 52.57 for OX and CC (range; 39.2–65.5 OX, 34.3–64 CC). Mean final WOMAC scores are reported as 84.9 and 87 for OX and CC, respectively.

The current data suggest that total hip arthroplasty utilizing Oxinium femoral heads is safe and effective. Additional follow-up of the current cohort will be performed in order to fully assess mid- to long-term clinical outcomes.

Background: Hip fracture trials have employed a wide range of patient-reported outcomes (PRO) suggesting a lack of consensus among clinicians on what are considered the most relevant outcomes. Variability in functional outcome reporting in hip fracture management creates challenges in the comparison of results across trials. The purpose of this study was to conduct a systematic review of the functional outcomes fielded in randomized controlled trials in post-operative hip fracture treatment for the aged. We hypothesized that over time there had been an increase in patient-reported outcomes along with aggregate scoring systems of hip function.

Methods: An electronic database search was conducted using key terms combining: ‘hip fracture’ with ‘RCT’ with ‘age 65 years and over’. s and titles were screened in duplicate and independently. All of the articles that met eligibility criteria were reviewed using the 21-point Detsky Quality Assessment Scale.

Results: In 2451 citations, 86 studies were included and also met accepted standards of inter-observer reliability (kappa, 0.92; 95% confidence interval, 0.87 to 0.98). The mean score (and standard error) for the quality of the randomized trials was: 75.8% ± 1.76% (95% confidence interval, 72.3%–79.3%) and 27 (32.6%) of the trials scored < 75%. Medical trials had a higher mean quality score than did surgical trials (83.7% compared with 72.7 %, p = 0.025). 59 trials (30 Surgical, 11 medical and 18 rehabilitation trials) scored > 75% in quality. Out of 86 trials, 8 (13.6%) used EQ-5D for utility and 6 (10.1%) used the SF-36 health status measures. At most, 12 trials used the same composite score: 12 (13.9%) ADL Katz Index, 9 (10.4%) trials used the HHS and 8 (9.3%) trials used Parker’s mobility score.

Conclusion: Although in the past decade more studies have made use of outcome instruments that capture both impairment and functional status in one aggregate score, there is a lack of standardized assessment.

Introduction: This study aimed to determine the accuracy of computer navigation in simulated fixation of femoral neck and supracondylar femoral fractures using different sizes of guidewires and drills from commercially available cannulated screw systems.

Methods: Simulated fracture fixation was performed with 2.5mm, 2.8mm and 3.2mm threaded guidewires and 3.2mm and 5mm drill bits using 20 4th generation synthetic femurs. The drill or guide wire was inserted in the synthetic femurs, using fluoroscopy based computer navigation (24 drills/guidewires in each group). Pre and postoperative fluoroscopy images were acquired with the C-arm and synthetic bone in the same orientations. Virtual and real wire/drill positions were compared, and errors calculated for each diameter of drill/guidewire (sum AP + Lateral error (mm)). Errors were compared using a general linear model with Tukey adjustment for multiple comparisons. Statistical significance at a two-tailed p-value < 0.05.

Results: The mean error for the 5.0mm drill (3.20mm) was significantly less than all the threaded wires (p< 0.05). The mean error for the 3.2mm drill (5.68mm) was significantly less than the 2.5mm guidewire (9.27mm) p< 0.05, and less than the 2.8mm (8.19mm) and 3.2mm (7.14mm) threaded wires.

Discussion: For cannulated screws, the 3.2mm drill was the most accurate size tested. The most accurate drill, 5mm, would allow solid screw insertion. However, its large size may preclude screw repositioning, and unlike a cannulated screw, would not maintain fracture position whilst the screw was being inserted.

Introduction: This study compared the accuracy of reduction of intra-medullary nailed femoral shaft fractures, comparing conventional and computer navigation techniques.

Methods: Twenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9–53mm in length. All fractures were fixed with antegrade 9mm diameter femoral nails on a radiolucent operating table. Five fractures (control) were fixed with conventional techniques. Fifteen fractures (study) were fixed with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. The surgeon was blinded to defect size. Two landmark protocols were used in the study group referencing the piriform fossa (Group A, n=10) or proximal shaft axis (Group B, n=5). Postoperative CT scans, blindly reported by a musculoskeletal radiologist, were used to compare femoral length and rotation with the normal leg.

Results were analysed using ANOVA with 95% Confidence Intervals.

Results: The control and study groups were not statistically different with respect to age of cadaver or size of femoral defect. Results: The mean leg length discrepancy in the study groups were significantly less (3.6mm (95% CI 1.072 – 6.128) and 4.2mm (95% CI 0.63–7.75), compared with 9.8mm (95% CI 6.225 – 13.37) in the control group (p< 0.023). The mean torsional deformities in the study groups were 8.7 degrees (95% CI 4.282 – 13.12) and 5.6 degrees (95% CI -0.65 – 11.85), compared with 9 degrees (95% CI 2.752 – 15.25) in the control group (p=0.650). Within the navigated study group, length discrepancy was similar in subgroups 1 (3.6mm) and 2 (4.2mm). Torsion appeared more accurate in group 2 (5.6 degrees) than group 1 (8.7 degrees), although this was not statistically significant.

Discussion: Computer navigation significantly improves the accuracy of femoral shaft fracture fixation with regard to length. With further modifications to improve reduction of rotational deformity, it may be a useful technique in the treatment of femoral fractures.

Aim of the study: To evaluate the use of a gelfoam sponge as a scaffold material in delivering osteoblast cells transfected with the VEGF gene for fracture repair.

Methods: In vitro: Osteoblasts were cultured from periosteum of rabbit bone and labeled with the visible CMTMR. Commercially available gelfoam with 12 pieces (each 3 × 3 × 3 mm3) was impregnated and cultured with the labelled cells (1×106) in a 12 wells plate for 1, 3 and 7 days. We embedded the gelfoam with labeled cells in an OCT compound enface, and the sections were then examined under a fluorescent microscope. In vivo: Osteoblasts were transfected with VEGF by use of SuperFect (Qiagen Inc) and cultured for 24 hours. The gelfoam pieces were impregnated with the transfected cells (5×106) saline solution for 30 minutes and placed into a segmental bone defect created in the rabbit tibia for 7 (n=3) and 14 (n=3) days. The specimens including the new bone were cut through each site of the segmental defect and embedded in paraffin. The sections were dewaxed and immunostained with mouse anti-human VEGF.

Results: In vitro: CMTMR-labeled cells survived and were detected within gelfoam at different time intervals (days 1, 3 and 7). In vivo: Immunostained VEGF proteins were visualized in the tissues surrounding the residual gel-foam at the fracture site at days 7 and 14 post surgery.

Conclusion: Our results indicate that the labeled/transfected cells are capable of growth in a gelfoam sponge both in vitro and in vivo.

Purpose: In a prospective randomized clinical trial, we have previously reported the “limb-specific” results comparing operative (plate fixation) versus non-operative (sling) treatment for completely displaced fractures of the shaft of the clavicle. We also sought to determine the effect that a fracture of the shaft of the clavicle had on general health status, as measured by the SF-36 General Health Status instrument. We then evaluated the effects of different treatment methods (operative versus non-operative), on general health scores.

Materials: We performed a multi-center, randomized clinical trial of operative versus non-operative treatment of completely displaced clavicular shaft fractures in 111 patients. In addition to radiographic, surgeon-based, and limb-specific data we prospectively gathered SF-36 questionnaires at baseline, and at 6 weeks and 3, 6, 12, and 24 months post-injury.

Results: Both groups had SF-36 scores equivalent to or slightly superior to population norms at baseline. A clavicular shaft fracture had a significant negative effect on SF-36 scores (especially the physical components) in both groups at 6 weeks (p< 0.01) and 3 months (p> < 0.01). There was a statistically greater decrease in Physical Component Scores (PCS) in the non-operative group compared to the operative group (P> < 0.05). At 6 months, scores had returned to pre-operative levels in the operative group, but remained significantly decreased in the non-operative group (p=0.04). This difference persisted at the one and two year points.

Conclusions: A displaced fracture of the clavicular shaft has a clinically significant negative effect on general health status scores. This effect can be mitigated by primary operative fixation, which restores scores to normal levels by six months post-injury. Patients treated non-operatively for a displaced fracture of the shaft of the clavicle demonstrated lower PCS scores at two years post-injury.

Background: The literature on hip fractures is increasingly reporting patient-reported outcomes along with aggregate scoring systems. However, this rapid growth in the number and types of patient-based outcomes can be confusing. The purpose of this paper is to conduct a systematic review of the functional outcome instruments fielded in high quality randomized clinical trials evaluating postoperative hip fracture management and rehabilitation in the aged.

Methods: An electronic database search was conducted using a variety of key terms combining: ‘hip fracture’ with ‘RCT’ with ‘age 65 years and over’. Abstracts and titles were screened in duplicate and independently. Studies were eligible based on the following criteria: hip fracture, randomized controlled trial, mean age of 65 years, and in the English language. Studies were excluded based on the following criteria: inclusion of fractures other than hip, minimum age of patient enrolment < 50 years old and prevention or fracture risk reduction as primary outcome of study. All of the articles that met eligibility criteria were reviewed using the Detsky Quality Assessment Scale.

Results: In 2451 citations, 86 studies were included and also met accepted standards of inter-observer reliability (kappa, 0.92; 95% confidence interval, 0.87 to 0.98). Discordance was resolved by consensus. The mean score (and standard error) for the quality of the randomized trials was: 75.8% ± 1.76% (95% confidence interval, 72.3%–79.3%) and 27 (32.6%) of the trials scored < 75%. Medical trials had a higher mean quality score than did surgical trials (83.7% compared with 72.7 %, p = 0.025). Data was abstracted from the 59 trials (30 Surgical, 11 medical and 18 rehabilitation trials) scoring > 75% in quality. Surgical trials had 16.7% more measures of disability than measures of impairment. Furthermore, 70% of the surgical trials used composite scores when compared to either medical or rehabilitation trials. Eight trials (13.6%) used EQ-5D for utility and 6 (10.1%) used the SF-36 health status measures. At most, 10 trials used the same composite score: 10 (16,9%) ADL Katz Index, 9 (15.2%) trials used the Harris hip score and 5 (8.5%) trials used Parker’s mobility score.

Discussion/Conclusion: Although there is a trend towards studies assessing functional recovery as a primary outcome in the aged with hip fractures, none of the measures were used consistently. A lack of standardized assessment in these groups of patients will overestimate treatment effects.

The effect of cup geometry in uncemented Total Hip Arthroplasty has not been investigated. We reviewed the radiological and clinical results of 527 primary total hip arthroplasties. We assessed the bone ingrowth potential of two geometric variations of an uncemented cup and compared hydroxyappetite and porous coated shells.

Patients undergoing primary hip arthroplasty between 1997 and 2004 were prospectively entered into an arthroplasty database. Patients were reviewed at 1,2,4,5,8 and 10 years post surgery. Three acetabular shell types were used. These included hemispherical cups with porous or hydroxyapatite coating, and cups with peripheral expansion with porous coating. Radiographs with minimum 1-year follow-up were examined in 542 cases, using digital templating software. Radiographs were assessed for signs of bone in-growth, lucent lines, migration and polyethylene wear. Survivorship analysis was performed using Kaplan-Meier analysis with 95% confidence intervals. Radiological findings and cup type were analysed using Fishers exact test.

Radiological evidence of bone ingrowth was seen in 82% of hemispherical cups, compared with 59% of peripherally expanded cups, which was significant (p,0.05). Bone ingrowth was not affected by the presence of HA coating. The most common diagnoses were osteoarthritis (67%) and avascular necrosis (12%). The mean age was 56 years. Survivorship with revision or impending revision for aseptic loosening was 95.6% at 7 years (95%CI 1.0134-0.8987). The 3 revisions and 1 impending revision for loosening were in patients with avascular necrosis (3) or previous acetabular and femoral osteotomies for DDH (1), with a mean age of 44 years.

Hemispherical shells have improved radiographic outcome in comparison with peripherally expanded components. At 7 years, clinical results are similar for both components.

This study compared the accuracy of reduction of intra-medullary nailed femoral shaft fractures, comparing conventional and computer navigation techniques.

Twenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9–53mm in length. All fractures were fixed with antegrade 9mm diameter femoral nails on a radiolucent operating table. Five fractures (control) were fixed with conventional techniques. Fifteen fractures (study) were fixed with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. The surgeon was blinded to defect size. Two landmark protocols were used in the study group referencing the piriform fossa (n=10) or proximal shaft axis (n=5). Postoperative CT scans, blindly reported by a musculoskeletal radiologist, were used to compare femoral length and rotation with the normal leg. Results were analysed using the Wilcoxon two-sample test.

The mean leg length discrepancy in the study group was 3.8mm (range 1–9), compared with 9.8mm(range 0–17) in the control group (p=0.076). The mean torsional deformity in the study group was 7.7 degrees (range 20–2) compared with 9 degrees (range 0–22) in the control group (p=0.86). Within the navigated study group, length discrepancy was similar in subgroups A (3.6mm) and B (4.2mm). Torsion appeared more accurate in group B (5.6 degrees) than group A (8.7 degrees), although not significantly.

Computer navigation appears to improve leg length discrepancy following femoral nailing. Technique modification during the study improved rotational accuracy, and with further improvement, will make this technique applicable to femoral fracture fixation.

In perfroming hip resurfacing arthroplasty, concern has been expressed as to the proximity of the femoral neurovascular bundle during the anterior capsulotomy and the risk of damage during this maneuver. We therefore aimed to identify the proximity of the femoral nerve, artery and vein during an anterior capsulotomy done during a hip resurfacing procedure using the posterior approach.

A standard posterior approach was performed in 5 fresh frozen cadavic limbs. An anterior incision was then used to measure the distance of the femoral neurovascular structures to the anterior capsule. Measurements from the most posterior aspect of the vessels and nerves to the most anterior aspect of the anterior capsule were taken prior to hip dislocation. The femoral head was then dislocated, and measurements were made with the hip in both flexion and extension. In a separate group of eleven patients that underwent routine MR imaging of the hip, measurements were taken to assess the proximity of the anterior joint capsule to the femoral neurovascular bundle, by a specialist musculoskeletal radiologist who had no prior knowledge of the results obtained during the cadaveric dissection

All 5 cadaveric limbs were utilised. 3 were male and 2 were female. The average age was 72.4 years (range 56–84). The patients whom underwent routine MR imaging incorporated 6 males and 5 females with a mean age of 43.7 years (age range 18–64 years). There was no significant difference between the mean distances to the nerve (p=0.21), artery (p=0.21) or vein (p=0.65) between the MR and cadaveric groups. Prior to dislocation the femoral artery and vein were closest to the anterior capsule (mean distance of 21mm) and the femoral nerve was the furthest away (mean distance 25mm). Following dislocation there was a significant increase (25mm to 31mm) in mean distance to the femoral nerve when the superior capsule was cut with the hip in a flexed position (p=0.01) and to the femoral artery in flexion (increase mean distance from 21mm to 35mm) (p< 0.0001) and in extension(increase mean distance from 21mm to 31mm) (p=0.005). When the inferior capsule was cut, there was a significant increase (25mm to 31mm) in mean distance to the femoral nerve and femoral artery when the hip was dislocated and the capsule cut with the hip in flexion (increase mean distance from 21mm to 27mm) (p=0.019) and in extension(increase mean distance from 21mm to 28mm) (p=0.015).

This study suggests that the neurovascular structures are relatively well protected during an anterior capsulotomy performed during hip resurfacing. The procedure may be safer if the capsulotomy is performed with the hip dislocated and the hip in a flexed position while cutting the antero-superior aspect and in an extended position while cutting the antero-inferior aspect.

The purpose of this study was to develop a cell-based VEGF gene therapy in order to accelerate fracture healing and investigate the effect of VEGF on bone repair in vivo.

Twenty-one rabbits were studied. A ten millimeter segmental bone defect was created after twelve millimeter periosteal excision in the middle one third of each tibia and each tibia was plated. Primary cultured rabbit fibroblasts were transfected by use of SuperFect (Qiagen Inc) with pcDNA-VEGF. 5.0 X 106 cells in 1ml PBS were delivered via impregnated gelfoam into the fracture site. Experimental groups were:

Transfected fibroblasts with VEGF (n=7),

Radiology: Fracture healing was defined as those with bone bridging of the fracture defect. After ten weeks, fourteen tibial fractures were healed in total including six in group one, four in group two and four in group three. The VEGF group had an earlier initial sufficient volume of bridging new bone formation. Histological evaluation demonstrated ossification across the entire defect in response to the VEGF gene therapy, whereas the defects were predominantly fibrotic and sparsely ossified in groups two and three. Numerous positively stained (CD31) vessels were shown in the VEGF group. MicroCT evaluation showed complete bridging for the VEGF group, but incomplete healing for groups two and three. Micro-CT evaluation of the new bone structural parameters showed that the amount of new bone (volume of bone (VolB) x bone mineral density (BMD)), bone volume fractions (BVF), bone volume/tissues (BV/TV), trabecular thickness (Tb.Th), number (Tb.N) and connectivity density (Euler number) were higher; while structure model index (SMI), bone surface/bone volume (BS/BV), and trabecular separations (Tb.Sp) were lower in the VEGF group than the other groups. P-Values < 0.05 indicated statistical significance (ANOVA, SPSS) in all parameters except for SMI (0.089) and VolBx-BMD (0.197).

These results indicate that cell-based VEGF gene delivery has significant osteogenic and angiogenic effects and demonstrates the ability of cell based VEGF gene therapy to enhance healing of a critical sized defect in a long bone in rabbits.

The purpose of this study was to assess the accuracy of clinical assessment compared to imageless computer navigation in determining the amount of fixed flexion during knee arthroplasty.

In fourteen cadaver knees, a medial para-patella approach was performed and the navigation anatomy registration process performed. The knees were held in various degrees of flexion with two crossed pins. The degree of flexion was first recorded on the computer and then on lateral radiographs. The cadaver knees were draped as for a knee arthroplasty and nine examiners (three arthroplasty surgeons, three fellows, and three residents) were asked to clinically assess the amount of fixed flexion. Three examiners repeated the process one week later.

The mean error from the radiograph in the navigation group was 2.18 degrees (95%CI 2.18+/−0.917) compared to 5.57 degrees (CI 5.57+/− 0.715) in the observer group. The navigation was more consistent with a range of error of only 5.5 degrees (standard deviation 1.59). The observers had a range of error of 18.5 degrees (S.D. = 4.06). When analysing the observers’ error with respect to flexion (+) and extension (−), they tended to under-estimate the amount of knee flexion (median error=−4) whereas the navigation was more evenly distributed (median error=0). The highest correlation was found between navigation and the radiograph r=0.96. The highest observer correlation with the radiograph was a consultant surgeon (r=0.91) and the worst was from a resident (r=0.74). The intra-class correlation coefficient was 0.88 for the three surgeons who repeated the measurements; their mean error was 3.5 degrees with a range of fifteen degrees.

The use of computer navigation appears to be more accurate in assessing the degree of knee flexion, with a reduced range of error when compared to clinical assessment. It is therefore less likely to leave the patient with residual fixed flexion after knee arthroplasty.

The purpose of this study was to evaluate the effect of previous femoral osteotomy on the outcome of total hip replacement performed for degenerative arthritis secondary to developmental dysplasia of the hip.

Eighty three primary total hip arthroplasties were performed in sixty-nine patients with osteoarthritis secondary to developmental hip dysplasia (DDH) with a minimum three year follow up. Twenty six hips had undergone previous femoral osteotomy (eleven hips, femoral osteotomy alone (FO); fifteen hips, combined femoral and pelvic osteotomy and fifty-seven hips, no previous surgery. The non operative patients with DDH served as an age and sex matched control group (control). Cementless arthroplasty was performed in seventy-eight hips. The mean duration from femoral osteotomy to primary THA was 22.9 years. The mean follow up was 7.6 years (FO) and 7.2 years (control).

The overall revision rate was 15.4 % (FO) and 21.1 % in the Control group (p> 0.05). Twenty-one hips had one or more complications during or after surgery. The FO group had a higher femoral fracture rate (23.1%) compared to controls (10.5%) (p< 0.05). At latest mean follow-up (7.4 yrs (range, two to sixteen)), the mean Harris hip score was eighty-five (FO) and eighty-five (control group) (p> 0.05). The function and pain scores in the femoral osteotomy group were similar to the controls (p> 0.05). The requirement for bone grafting was similar and operative time significantly greater (FO) compared to controls. The frequency of radiolucent lines around the femoral component in the FO group (36%) was significantly higher than the control group (12.2%) (p< 0.05). Survival analysis was performed with the Kaplan-Meier method. At ten years, the survival of the acetabular component was 84.6%/73.6% and for the femoral component 92.2%/96% in the FO/control group.

Patients with a prior femoral osteotomy have no significant difference in functional outcome, overall complication rate or revision rate compared to controls. However, there is a significant increase in femoral fracture and operative time. Previous femoral osteotomy does not compromise the functional outcome of subsequent total hip arthroplasty.

To assess the accuracy of plain digitised radiographic images for measurement of neck-shaft and stem-shaft angles in hip resurfacing arthroplasty.

Fifteen patients having undergone hip resurfacing arthroplasty with the Birmingham Hip Resurfacing (BHR) were selected at random. Digital radiographs were analyzed by three observers. Each observer measured the femoral neck-shaft angles (NSA) of the pre-operative and stem-shaft angles (SSA) of the postoperative radiographs on two separate occasions spanning one week. The effect of femur position on SSA measured by digital radiographs was also analyzed. A BHR prosthesis was cemented into a third generation Sawbone composite femur. Radiographs were taken with the synthetic specimen positioned in varying angles of both flexion and external rotation in increments of 10° ranging from 0° to 90°.

The mean intraobserver difference in measured angle was 3.13° (SD 2.37°, 95% CI +/−4.64°) for the NSA group and 1.49° (SD 2.28°, 95% CI +/−4.47°) for the SSA group. The intraclass correlation coefficient for the NSA group was 0.616 and for the SSA group was 0.855. Flexion of the synthetic femur of twenty degrees resulted in a five degree discrepancy in measured SSA and flexion of forty degrees resulted in a thirteen degree discrepancy. External rotation of the synthetic specimen of twenty and forty degrees resulted in a three and nine degree discrepancy in measured SSA, respectively.

Patient malposition during radiographic imaging can contribute to erroneous NSA and SSA results. Significant intra- and inter-observer variation was noted in the measurement of neck shaft angle however, variation was less marked for measurement of stem shaft angle.

The purpose of this study was to evaluate functional outcome following supracondylar femur fractures using patient-based outcome measures.

Patients having sustained supracondylar femur fractures between 1990 and 2004 were identified from the fracture databases of two level-one trauma centres. Three patient-based outcome measures, the Short Form-36 (SF-36) Version two, the Short Musculoskeletal Functional Scale (SMFA), and the Lower Extremity Functional Scale (LEFS) were used to evaluate functional outcome. Each patient’s medical record was also reviewed to obtain information regarding potential predictors of outcome, including age, gender, fracture type (AO classification), presence of comorbidities, smoking status, open vs. closed fracture, and occurrence of complications. Univariate and multivariate models were then used to identify significant predictors of outcome, as reflected in the SMFA bother and dysfunction scores.

Sixty-one patients (thirty-five males and twenty-six females) with an average age (at time of injury) of 53 ± 18 years consented to participate. The average length of follow-up was 64 ± 34 months from the time of injury. Mean SF-36 V2 scores were lower than Canadian population norms indicating decreased function or greater pain, while mean SMFA scores were higher than published population norms indicating greater impairment and bother. The mean LEFS score was 40.78 ± 15.90 out of a maximum score of eighty. At the univariate level, the presence of complications was a significant predictor of both the SMFA bother (p=0.002) and dysfunction scores (p=0.015), while positive smoking status was a significant predictor of the bother score (p=0.002). Based on a multivariate linear regression model, the presence of complications (p=0.013) and positive smoking status (p=0.011) were both significant predictors of a higher SMFA bother score. In the multivariate model for SMFA dysfunction score, the presence of complications (p=0.014) and the presence of comorbidities (p=0.017) were significant predictors of a higher score.

Comparing SF-36 and SMFA scores with published population norms, supracondylar femur fractures were associated with residual impact. Based on our analysis, smoking, the presence of medical comorbidities at the time of fracture, and the occurrence of complications following fracture repair were the main predictors of poorer patient outcomes following supracondylar femur fracture.

This study examines the biomechanical performance of five types of fixation techniques in a model of pathological fracture of the diaphyseal humerus.

In forty synthetic humeri, a hemi cylindrical defect centered in the middle third of the diaphysis was created. A transverse fracture was created through the centre of each defect. The bones were randomly assigned to five groups. Group A was fixed with standard ten hole DCP plates centered over the defect with five screws inserted on either end. In group B, the screw holes were injected with bone cement and then the screws and plate were reapplied while the cement was still soft. The defect was also filled with cement. Group C was fixed by injecting the cement into the entire intramedullary canal. The fracture was then reduced and the screws and plate were applied once the cement had hardened. In group D, the specimens were fixed with locked antegrade IM nail with one proximal and one distal interlocking screw. Group E was same as D except that the defect was filled with cement. Each specimen was tested in external rotation to failure by fracture.

There was no significant difference in torsional stiffness between groups B, C, and E (P> 0.16), whereas there were differences between all other groups using pairwise comparisons(p< 0.001). Groups B, C, and E were of highest stiffness followed by A and then D. Group C had the highest torque to failure, followed by groups A/B and then D/E. Total cumulative energy to failure for group C was statistically greater than each of B, D, and E (p< 0.005), but not different from A, though it approached significance (p=0.057).

This study demonstrates that, in a model of a fracture through a hemicylindrical defect in the middiaphysis of the humerus, fixation with a broad ten-hole dynamic compression plate after filling the entire medullary canal with cement is associated with the highest torque to failure and energy to failure with torsional forces. This fixation technique may best accomplish the clinical goal of maximal initial stability.

We aimed to establish if radiological parameters, dual energy x-ray absorbtiometry (DEXA) and quantitative CT (qCT) could predict the risk of sustaining a femoral neck fracture following hip resurfacing.

Twenty-one unilateral fresh frozen femurs were used. Each femur had a plain AP radiograph, DEXA scan and quantitative CT scan. Femurs were then prepared for a Birmingham Hip Resurfacing femoral component with the stem shaft angle equal to the native neck shaft angle. The femoral component was then cemented onto the prepared femoral head. No notching of the femoral neck occurred in any specimens. A repeat radiograph was performed to confirm the stem shaft angle. The femurs were then potted in a position of single leg stance and tested in the axial direction to failure using an Instron mechanical tester. The load to failure was then analysed with the radiological, DEXA and qCT parameters using multiple regression.

The strongest correlation with the load to failure values was the total mineral content of the femoral neck at the head/neck junction using qCT r= 0.74 (p< 0.001). This improved to r=0.76 (p< 0.001) when neck width was included in the analysis. The total bone mineral density measurement from the DEXA scan showed a correlation with the load to failure of r=0.69 (p< 0.001). Radiological parameters only moderately correlated with the load to failure values; neck width (r=0.55), head diameter (r= 0.49) and femoral off-set (r=0.3).

This study suggests that a patient’s risk of femoral neck fracture following hip resurfacing is most strongly correlated with total mineral content at the head/neck junction and bone mineral density. This biomechanical data suggests that the risk of post-operative femoral neck fracture may be most accurately identified with a pre-operative quantitative CT scan through the head/neck junction combined with the femoral neck width.

To investigate differences between the Reamer Irrigator Aspirator and the AO reamer on fat embolism outcome using a porcine model.

All animal procedures were approved and performed in accordance with the Animal Care Committee at St. Michael’s hospital. Following anesthetic administration, the animals were stabilised for thirty minutes. One third of the pig’s blood volume was withdrawn to simulate hemorrhagic shock. Each animal was kept in a state of hypovolemia for an hour before transfusion and resuscitation. Once the animal was stabilised surgical exposure of the distal femur was completed. A 12 mm Reamer Irrigator Aspirator or AO reamer was used depending on which group the animal was assigned to. Blood work was obtained at: baseline, immediately after induction of hypovolemia, one hour post hypovolemia, post stabilization, one minute, five minutes, 1.5 hours and three hours after reaming. The results were analyzed for activation of the coagulation system, platelet and neutrophil activation, and cytokine elevation. ANOVA was the primary tool used to assess statistical significance.

There was no statistical difference between the two reamers with respect to PT, APTT, and fibrinogen. There was a statistical difference in D-dimer at 1.5 and three hours post-reaming, with the RIA showing a lower value. Neither reamer demonstrated any systemic platelet nor neutrophil activation. TNF-alpha spiked immediately post-reaming with the RIA group returning to baseline values and the AO group remaining elevated. There is a spike in IL-1B post reaming in the AO group, however this was not seen in the RIA group. No statistical difference was detected between the two reamers.

All markers for platelet and neutrophil activation and the coagulation cascade were measured at the systemic level. Although there is no statistical difference between the RIA and AO reamer, it is possible that activated cells were removed from the systemic circulation and sequestered as thrombi in the pulmonary microvasculature. This hypothesis may be supported by a drop in platelet count and an increase in D-dimer, with the AO reamer suggesting greater thrombi formation. The trends in IL-1B and TNF-alpha seem to suggest that the RIA abrogates the post-reaming proinflammatory state.

We aimed to identify whether patients in lower socioeconomic groups had worse function prior to total knee arthroplasty and to establish whether these patients had worse post-operative outcome following total knee arthroplasty. Data was obtained from the Kinemax outcome study, this was a prospective observational study of 974 patients undergoing primary total knee arthroplasty for osteoarthritis. The study was undertaken in thirteen centers, four in the United States, six in the United Kingdom, two in Australia and one in Canada. Pre-operative data was collected within six weeks of surgery and patients were followed for two years post-operatively. Pre-operative details of the patient’s demographics, socioeconomic status (education and income), height, weight and co-morbid conditions were obtained. The WOMAC and SF-36 scores were also obtained. Multivariate regression was utilised to analyse the association between socioeconomic status and the patient’s pre-operative scores and post-operative outcome. During the analysis, we were able to control for variables that have previously been shown to effect pre-operative scores and post-operative outcome. Patients with a lower income had a significantly worse pre-operative WOMAC pain (p=0.021) and function score (p=0.039) than those with higher incomes. However, income did not have a significant impact on outcome except for WOMAC Pain at 12-months (p=0.014). At all the other post-operative assessment times, there was no correlation between income and WOMAC Pain and WOMAC Function. Level of education did not correlate with pre-operative scores or with outcome at any time during follow-up. This study demonstrates that across all four countries, patients with lower incomes appear to have a greater need for total knee arthroplasty. However, level of income and educational status did not appear to effect the final outcome following total knee arthroplasty. Patients with lower incomes appear able to compensate for their worse pre-operative score and obtain similar outcomes post-operatively.

Alignment of the femoral component during hip resurfacing has been implicated in the early failure of this device. Techniques to facilitate a more accurate placement of the femoral component may help prevent these early failures. We aim to establish whether the use of imageless computer navigation can improve the accuracy in alignment of the femoral component during hip resurfacing.

6 pairs of cadaveric limbs were randomized to the use of computer navigation or standard instrumentation. All hips had radiographs taken prior to the procedure to facilitate accurate templating. All femoral components were planned to be implanted with a stem shaft angle of 135 degrees. The initial guide wire was placed using either the standard jig with a pin placed in the lateral cortex or with the use of an imageless computer navigation system. The femoral head was then prepared in the same fashion for both groups. Following the procedure radiographs were taken to assess the alignment of the femoral component.

The mean stem shaft angle in the computer navigation group was 133.3 degrees compared to 127.7 degrees in the standard instrumentation group (p=0.03). The standard instrumentation group had a range of error of 15 degrees with a standard deviation of 4.2 degrees. The computer navigated group had a range of error of only 8 degrees with a standard deviation of 2.9 degrees.

Our results demonstrated that the use of standard alignment instrumentation consistently placed the femoral component in a more varus position when compared to the computer navigation group. The computer navigation was also more consistent in its placement of the femoral component when compared to standard instrumentation. We suggest that imageless computer navigation appears to improve the accuracy of alignment of the femoral component during hip resurfacing.

Purpose: To determine the differences in bone remodelling between a metaphyseal and a diaphyseal fixed stem in uncemented total hip arthroplasty.

Methods: Twenty-three patients undergoing uncemented total hip arthroplasty (28 hips) utilizing a metaphyseal fit stem were matched to 27 patients (32 hips) undergoing uncemented total hip arthroplasty utilizing a diaphyseal fit stem. Patients were matched for age, gender and follow-up. All patients were assessed by clinical and radiographic examination at 6 weeks, 3 months, 6 months and yearly thereafter. Radiographs were assessed for periprosthetic bone remodelling, canal fill, canal shape and bone quality using the cortical index and the Singh index. At latest follow-up all radiographs were assessed for frequency and time of appearance of spot welds, cortical hypertrophy and development of pedestal formation. All patients were assessed clinically utilizing the modified Harris hip score.

Results: At one year there was no difference in the clinical results between the two groups of patients utilizing the modified Harris hip score 90.6 + 1.5 in metaphyseal fit stems versus 91.7 + 1.7 for diaphyseal fit stems (p> 0.05). There was no statistical difference between the two groups in either femoral canal shape or bone quality–canal-to-calcar ratio 0.49 versus 0.45 (p> 0.05); cortical index 0.45 versus 0.44 (p> 0.05); Singh index 3.44 versus 3.70 (p> 0.05). In assessing canal fill proximal canal fill was statistically greater in metaphyseal fit stems and distal canal fill was significantly greater in diaphyseal fit stems (p< 0.01). There was a statistically significant increase in the frequency and timing of spot welds in metaphyseal stems at 3 months and 6 months (p< 0.05) but no difference in the frequency of spot welds at 1 year and 2 years. Cortical hypertrophy was significantly increased at 6 months, 1 year and 2 years in metaphyseal fit stems as compared to diaphyseal fit stems (p< 0.05). There was no difference in pedestal formation at 1 year or 2 years between the two stem groups (p> 0.05).

Conclusions: After one year the only significant difference between these two groups of patients is increased cortical hypertrophy in those patients undergoing metaphyseal versus diaphyseal stem insertion. Both stem designs demonstrated bone remodelling with no differences in spot welds or pedestal formation. At two years there was no functional difference between these two patient groups.

Purpose: The purpose of this study was to evaluate total hip arthroplasty (THA) in the treatment of posttraumatic arthritis following acetabular fracture and to compare the long-term outcome of THA after previous open reduction and internal fixation (ORIF) or conservative treatment of the acetabular fracture.

Method: Thirty-four patients (thirty-six hips) underwent total hip arthroplasty for arthritis resulting from acetabular fractures. There were twenty-six males (27 hips) and eight females (9 hips). The mean age at the time of hip arthroplasty was 49 years (range, 25–78 years). The mean follow-up was eight years and nine months (range, 4–17 years). The mean interval from fracture to arthroplasty was 7.5 years (range, 5 months-29 years). Two patients died of unrelated causes and two patients were lost to follow up. Thirty patients (32 hips) were available for latest follow up. Twenty-one hips had been previously treated by open reduction internal fixation and 11 hips had conservative treatment.

Results: Sixteen patients achieved and maintained a good to excellent result over the course of the follow-up. There was no difference in improvement of mean Harris Hip Score between both groups (p> 0.05).

Ten out of 32 hips required revision; 9 acetabular components were revised because of aseptic loosening (3), osteolysis/excessive wear (4), instability (1) and infection (1) with a total revision rate of 28%. Eight patients needed acetabular revision alone, one femoral revision alone and one revision of both components. There was no significant difference in bone grafting, heterotopic bone formation, revision rate, operative time and blood loss between the two groups (p> 0.05).

Conclusions: Those patients initially treated conservatively had similar long term results compared to those treated primarily by open reduction internal fixation. At long term follow-up the main problem identified was osteolysis and acetabular wear.

We aimed to establish if radiological parameters, dual energy x-ray absorbtiometry (DEXA) and quantitative CT (qCT) could predict the risk of sustaining a femoral neck fracture following hip resurfacing. 21 unilateral fresh frozen femurs were used. Each femur had a plain AP radiograph, DEXA scan and quantitative CT scan. Femurs were then prepared for a Birmingham Hip Resurfacing femoral component with the stem shaft angle equal to the native neck shaft angle. The femoral component was then cemented onto the prepared femoral head. No notching of the femoral neck occurred in any specimens. A repeat radiograph was performed to confirm the stem shaft angle. The femurs were then potted in a position of single leg stance and tested in the axial direction to failure using an Instron mechanical tester. The load to failure was then analysed with the radiological, DEXA and qCT parameters using multiple regression. The strongest correlation with the load to failure values was the total mineral content of the femoral neck at the head/neck junction using qCT r= 0.74 (p< 0.001). This improved to r=0.76 (p< 0.001) when neck width was included in the analysis. The total bone mineral density measurement from the DEXA scan showed a correlation with the load to failure of r=0.69 (p< 0.001). Radiological parameters only moderately correlated with the load to failure values; neck width (r=0.55), head diameter (r= 0.49) and femoral off-set (r=0.3). This study suggests that a patient’s risk of femoral neck fracture following hip resurfacing is most strongly correlated with total mineral content at the head/neck junction and bone mineral density. This biomechanical data suggests that the risk of post-operative femoral neck fracture may be most accurately identified with a pre-operative quantitative CT scan through the head/neck junction combined with the femoral neck width.

Introduction: We aimed to examine the effect of neck notching during hip resurfacing on the strength of the proximal femur.

Methods: Third generation composite femurs that have been shown to replicate the biomechanical properties of human bone were utilised. Imageless computer navigation was used to position the initial guide wire during head preparation. Six specimens were prepared without a superior notch being made in the neck of the femur, six were prepared in an inferiorly translated position to cause a 2mm notch in the superior femoral neck and six were prepared with a 5mm notch. All specimens had radiographs taken to ensure that the stem shaft angle was kept constant. The specimens were then loaded to failure in the axial direction with an Instron mechanical tester.

A three dimensional femoral finite element model was constructed and molded with a femoral component constructed from the dimensions of a Birmingham Hip Resurfacing. The model was created with a superior femoral neck notch of increasing depths.

Results: The 2mm notched group (mean load to failure 4034N) were significantly weaker than the un-notched group (mean load to failure 5302N) when tested to failure (p=0.017). The 5mm notched group (mean load to failure 3121N) were also significantly weaker than the un-notched group (p=0.0003) and the 2mm notched group (p=0.046). All fractures initiated at the superior aspect of the neck, at the component bone interface. The finite element model revealed increasing Von Mises stresses with increasing notch depth.

Discussion: A superior notch of 2mm in the femoral neck weakens the proximal femur by 24% and a 5mm notch weakens it by 41%. This study provides biomechanical evidence that notching of the femoral neck may lead to an increased risk of femoral neck fracture following hip resurfacing due to increasing stresses in the region of the notch.

Introduction: It has been suggested that femoral component alignment in the coronal plane affects the risk of sustaining femoral neck fracture following hip resurfacing. Previous literature suggests that increasing the stem shaft angle to an extreme valgus position produces the most favourable biomechanical properties following femoral component insertion. We examined the effects of femoral component alignment during hip resurfacing on proximal femur strength.

Methods: 3^rd generation composite femurs shown to replicate biomechanical properties of human bone were used. The bones were secured in a position of single leg stance and tested with an Instron mechanical tester. Imageless computer navigation was used to position the guide wire during femoral head preparation. Specimens were placed in 115, 125 and 135 degrees of stem shaft angulation. No notching was made in the femoral neck during head preparation. The femoral components were cemented in place. Radiographs were taken ensuring that stem shaft angles were correct. Specimens were loaded to failure in the axial direction.

Results: A component position of 115 degrees compared to 125 degrees reduced load to failure from 5475N to 3198N (p=0.009). A position of 135 degrees (5713N) compared to 125 degrees (5475N) did not significantly alter the load to failure (p=0.347). Component positioning at a stem shaft angle below 125 degrees resulted in a significant reduction in strength of the proximal femur. Placement of the component at 115 degrees reduced the load to failure by 42%.

Discussion: Our findings suggest that a varus orientation may be at risk for causing femoral neck fracture. The advantages of increasing valgus angle beyond 125 degrees may not provide as much reduction in the incidence of femoral neck fracture as previously suggested, particularly when considering the inherent risk of femoral neck notching in these positions.

Introduction: When performing a hip resurfacing procedure through the postero-lateral approach, concern has been expressed as to the proximity of the femoral neurovascular bundle during the anterior capsulotomy. We aimed to identify the proximity of the femoral nerve, artery and vein during an anterior capsulotomy.

Methods: 5 fresh frozen cadaveric limbs were used. A standard postero-lateral approach was performed. An anterior incision was then made to identify the femoral neurovascular bundle. Measurements were taken prior to hip dislocation. The femoral head was dislocated, capsulotomy scissors were inserted though the posterior incision and positioned to cut the superior and then inferior aspects of the anterior capsule. The distance from the scissors to each of the neurovascular structures were recorded. Measurements were made with the hip in flexion and extension.

Results: Prior to dislocation the mean distance from the capsule was 25mm for the femoral nerve, 21mm for the artery and 21mm for the vein. Following dislocation, with the hip in extension the distance during cutting of the antero-superior capsule to the nerve, artery and vein was 31mm. With the hip in a flexed position, the distance from all three neurovascular structures increased by a mean of 5mm. When the scissors were positioned to cut the antero-inferior capsule in extension, the mean distances to the nerve, artery and vein were 31mm, 28mm and 28mm. When the hip was flexed, the distance to the nerve decreased by 2mm.

Discussion: Our study suggests that the neurovascular structures are relatively well protected during an anterior capsulotomy performed during hip resurfacing. The procedure may be safer if the capsulotomy is performed with the hip dislocated and the hip in a flexed position while cutting the antero-superior aspect and in an extended position while cutting the antero-inferior aspect.

Introduction: Notching of the femoral neck during preparation of the femur during hip resurfacing has been associated with an increased risk of femoral neck fracture. We aimed to evaluate this with the use of a finite element model.

Methods: A three dimensional femoral model was used and molded with a femoral component constructed from the dimensions of a Birmingham Hip Resurfacing. Multiple constructs were made with the component inferiorly translated in order to cause a notch in the superior femoral neck. The component angulation was kept constant. Once constructed the model was imported into the Ansys finite element model software for analysis. Elements within the femoral model were assigned different material properties depending on cortical and cancellous bone distributions. Von Misses stresses were evaluated near the notches and compared in each of the cases.

Results: In the un-notched case the maximum Von Mises stress was only 40MPa. However, with the formation of a 1mm notch the stress rose to 144MPa and in the 4 mm notch the stress increased to 423MPa. These values demonstrated that a 1mm notch increased the maximum stress by 361% while a 4mm notch increased the maximum stress by 1061%.

Discussion: This study demonstrated that causing a notch in the superior femoral neck dramatically increases the stress within the femoral neck. This may result in the weakening of the femoral neck and potentially predispose it to subsequent femoral neck fracture. The data suggests that even a small notch of 1mm may be detrimental in weakening the femoral neck by dramatically increasing the stress in the superior neck. This study suggests that any femoral neck notching should be avoided during hip resurfacing.

Introduction: It has been suggested that notching of the femoral neck during hip resurfacing weakens the proximal femur and predisposes to femoral neck fracture. We aimed to examine the effect of neck notching during hip resurfacing on the strength of the proximal femur.

Methods: 3^rd generation composite femurs that have been shown to replicate the biomechanical properties of human bone were utilised. The bone was secured in a position of single leg stance and tested with an Instron mechanical tester. Imageless computer navigation was used to position the initial guide wire during head preparation. Six specimens were prepared without a superior notch being made in the neck of the femur, six were prepared in an inferiorly translated position to cause a 2mm notch in the superior femoral neck and six were prepared with a 5mm notch. The femoral component was then cemented in place. All specimens had radiographs taken to ensure that the stem shaft angle was kept constant. The specimens were then loaded to failure in the axial direction.

Results: The 2mm notched group (mean load to failure 4034N) were significantly weaker than the un-notched group (mean load to failure 5302N) when tested to failure (p=0.017). The 5mm notched group (mean load to failure 3121N) were also significantly weaker than the un-notched group (p=0.0003) and the 2mm notched group (p=0.046). All fractures initiated at the superior aspect of the neck, at the component bone interface. All components were positioned in the same coronal alignment +/−2 degrees.

Discussion: A superior notch of 2mm in the femoral neck weakens the proximal femur by 24% and a 5mm notch weakens it by 41%. This study provides biomechanical evidence that notching of the femoral neck may lead to an increased risk of femoral neck fracture following hip resurfacing.

This study was undertaken to assess the contribution of pulmonary fat embolism to systemic platelet activation in a rabbit model of fat embolism. Fifteen NZW rabbits were randomly assigned into one of two groups: fat embolism and control. Fat embolism was induced via intramedullary canal pressurization with a 1–1.5 ml bone cement injection. Only the animals that underwent fat embolism displayed consistent platelet activation, as demonstrated by platelet degranulation and procoagulatory surface expression. These findings suggest that fat embolism plays a role in platelet activation and in the overall activation of hemostasis following trauma.

The objective of this study was to use a recently developed rabbit model of fat embolism to assess the systemic hemostatic response to pulmonary fat embolism.

Our findings demonstrate platelet activation following forced liberation of bone marrow contents into the circulation only in the FE group, as demonstrated by CD62P elevation (a marker of platelet degranulation) and annexin V elevation (a marker of procoagulatory surface expression). Platelet activation also coincided with significantly lower platelet counts in the FE group at two and four hours post embolism, suggesting platelet aggregation.

These findings suggest that fat embolism plays a role in platelet activation and in the overall activation of hemostasis following trauma.

Platelet count decreased significantly at two and four hours post knee manipulation only in the FE group. Annexin V expression increased significantly in the FE group at two and four hours post knee manipulation. Lastly, CD62P expression only increased significantly in the FE group at two hours post knee manipulation

Fifteen New Zealand White male rabbits were randomly assigned into one of two groups: control and fat embolism (FE). In FE group (n=8), the intramedullary cavity was drilled, reamed and pressurized with a 1–1.5 ml bone cement injection. In the control group (n=7), a sham knee incision was made, exposing both femoral condyles, but was immediately closed without further manipulations. All animals were mechanically ventilated for an additional monitoring period of four hours post-surgical closure. For flow cytometric evaluation of platelet activation, blood samples were stained with fluorescence-conjugated antibodies against CD41 (FITC), CD62P (P-selectin) and annexin V (FITC). Platelet events were identified by their characteristic CD41 staining and size and were analyzed using a flow cytometer. All animals were mechanically ventilated for four hours post surgical closure.

The implications of platelet activation following fat embolism are numerous, ranging from adherence and aggregation, to secretion of key components of both the coagulation and inflammatory cascades.

Bone transport/limb lengthening with circular external fixation has been associated with a prolonged period of time in the frame and a significant major complication rate following frame removal. We examined the results of bone transport in fifty-one limbs using the “monorail” technique and found a dramatically improved lengthening index (24.5 days/cm. – time in frame /cm. of length gained) and an absence of refracture or angulatory deformity following fixator removal. This technique is our treatment of choice for limb lengthening/bone transport.

We sought to determine patient oriented outcome and complication rates following b one transport using an external fixator placed over an intramedullary nail (the “monorail” technique).

Bone transport using the monorail technique is associated with a dramatically improved lengthening index and a lower major complication rate than traditional ring fixator methods. Patient satisfaction with the procedure was high.

Our study confirms the significant advantages of the monorail technique for bone transport/limb lengthening. The time in the fixator is dramatically reduced, and complications associated with earlier techniques such as angulatory deformity or refracture were not seen.

We identified forty-nine patients (fifty-one limbs) who had undergone bone transport using the monorail technique (external fixator placed over an intramedullary nail). There were thirty-five men and fourteen women with a mean age of thirty-five years (range 17–50). Pre-operative diagnoses included post traumatic length discrepancy/bone defect (forty-one), congenital short stature (six) and other (four). All patients had a unilateral fixator placed over an implanted intramedullary nail. Once length correction was achieved, the fixator was removed and the nail “locked”. The mean amount of lengthening was 5.5 cm. (range 2 – 18 cm.). The lengthening index was 24.5 days /cm. (duration of external fixation/cm. bone length gained), with a range from ten to fifty days /cm. There were nineteen complications (thirty-seven percent): nine premature consolidations, four infected pin sites, two hardware failures, two osteomyelitis, one DVT, one nonunion. There were no refractures, angulatory deformities or cases of intramedullary sepsis.

Clinicians ask patients “How are you now?” to ascertain treatment outcomes and to set a plan for subsequent care. However, sometimes patient views do not agree with those of the clinicians. This study compared patient and clinician views of outcome one to two years after an operatively managed extremity fracture and described any discordance. There were significant differences between groups, especially in areas such as pain and disruption of their personal and work lives. A discordance was observed between patient and physician views of recovery after fracture, likely associated with disruptions to personal life, unaccounted for in a clinician’s view of outcome.

Clinicians ask patients “How are you now?” to ascertain treatment outcomes and to set a plan for subsequent care. However, sometimes patient views differ from those of clinicians’.

The purpose of this study is to compare patient and clinician views of outcome one to two years after an extremity fracture and to describe any discordance.

Cross-sectional survey of patients one to two years after an operatively managed upper or lower extremity fracture. Patients were recruited from two tertiary care centres and completed a mailback questionnaire that included measures of health (DASH, SMFA), self-rated recovery, burden of illness (Illness Intrusiveness, Loss of self), symptoms, and work status. These were linked with clinical records of radiologic and clinical recovery.

Two hundred and fifty-five patients returned usable questionnaires. Mean age was forty-two years and 42% were female. Sixty-seven patients said that they were completely better (CB), one hundred and thirty-four almost better (AB) and fifty-four not completely better (NCB). Significant differences were found between groups. In four variables, NCB was distinct from AB/CB, while in all other variables, such as pain, disability and disruption of their personal and work lives, all three groups were unique (Duncan’s post hoc). However, of the patients who said they were not better, the radiologist and clinician reports stated that thirty (68%) and twenty-eight (64%) were healed, respectively.

A discordance was observed between patient and physician views of recovery after fracture. It appeared associated with disruptions to personal life that may not be accounted for in a clinician’s view of outcome.

Funding: Canadian Institutes of Health Research (CIHR)

Purpose: The purpose of this study was to evaluate total hip arthroplasty in the treatment of post-traumatic arthritis following acetabular fracture and to compare the long-term outcome of THA after previous open reduction and internal fixation or conservative treatment of the acetabular fracture.

Methods: Thirty-four patients (thirty-six hips) underwent total hip arthroplasty for arthritis resulting from an acetabular fracture. The mean age at the time of hip arthroplasty was 49 years. The mean follow-up was eight years and nine months (range, 4–17 years). The mean interval from fracture to arthroplasty was 7.5 years (range, 5 months-29 years). Twenty-three hips had been previously treated by open reduction and internal fixation and 12 hips had a conservatively treated fracture. An uncemented arthroplasty was performed in 31 hips, cemented arthroplasty in 2 patients and a hybrid replacement in 2 patients.

Results: Only 16 patients achieved and maintained a good to excellent result over the course of the follow-up. The mean Harris hip score improved from 44.5 points preoperatively to 72.76 points for operatively treated fractures (23 patients). The mean Harris hip score improved from 44.2 points preoperatively to 78.7 points for conservatively treated fractures (12 patients) (p> 0.05). Ten out of 35 hips required revision; 9 were revised because of aseptic loosening and one for infection with a total revision rate of 29%. Femoral bone quality was significant in predicting revision. No femoral radiographic loosening was found at latest follow-up. On the acetabular side, the rate of radiographic loosening was higher. There was no significant difference in bone grafting, heterotopic bone formation, revision rate, operative time and blood loss between the two groups (ORIF vs conservative treatment of acetabular fracture) (p> 0.05).

Conclusions: Outcome following total hip arthroplasty in the treatment of post-traumatic arthritis following acetabular fracture is less favourable than following primary osteoarthritis. Those patients initially treated conservatively had similar long term results compared to those treated primarily by open reduction and internal fixation. At long term follow-up, the main problem identified was osteolysis and acetabular wear.

When deciding on treatment for displaced mid-shaft clavicle fractures, patients often inquire if repair of (potential) nonunion results in outcome similar to acute fixation. We used objective muscle strength testing and patient-oriented outcome measures to examine this question. Late reconstruction of nonunion following displaced mid-shaft fractures of the clavicle results in restoration of objective muscle strength similar to that seen with immediate fixation. However, there was a significant loss in muscle endurance as well as a trend towards a decrease in outcome scores (DASH, Constant) following late reconstruction. This information is useful in surgical decision making and in counseling patients.

Using objectively measured strength and patient-oriented health-status instruments, we sought to determine if delay in repair of displaced, mid-shaft clavicle fractures negatively affected shoulder strength or outcome.

Late reconstruction of clavicle nonunion results in restoration of objective muscle strength similar to that seen with immediate fracture fixation, but there was a significant loss in muscle endurance as well as a trend towards a decrease in outcome scores (DASH, Constant).

All patients had sustained completely displaced, closed, isolated mid-shaft clavicle fractures. Fifteen patients had immediate plate fixation (mean 0.6 months post-fracture) and fifteen had plate fixation for non-union (mean fifty-eight months post-fracture). Objective muscle strength testing on the BTE was done a mean of twenty-nine months post-fixation (normal contralateral limb as control). There were no significant differences between acute fixation and delayed reconstruction groups with regards to strength of shoulder flexion (acute = 92.4%, delayed = 89.4%, p=0.56), shoulder abduction (acute = 98.8%, delayed = 96.7, p=0.75), external rotation (acute = 98.4%, delayed = 91.9%, p=0.29), or internal rotation (acute = 96.3%, delayed = 97.4%, p=0.87). However, there was a trend for improved Constant scores (acute = 94.5, delayed = 90, p=0.09) and the DASH scores (acute = 3.4, delayed = 9.0, p=0.09) in the acute fixation group. We found a significant decrease in muscle endurance with regards to shoulder flexion (acute = 107.0%, delayed = 71.1%, p=0.007) and a trend towards weaker shoulder abduction (acute = 103.1%, delayed = 88.7 %).

Funding: Mr. Potter was supported by a St. Michael’s Hospital Summer Student Scholarship

Purpose: In uncemented total hip arthroplasty, stem design is one of the important factors influencing bone remodeling. The purpose of this study was to determine the differences in bone remodeling between metaphyseal and diaphyseal fit stems.

Methods: Twenty-three patients undergoing total hip arthroplasty (28 hips) with metaphyseal fit stems were matched to 27 patients (32 hips) undergoing uncemented total hip arthroplasty with diaphyseal fit stems. Preoperative radiographs were assessed for canal fill, canal shape, and bone quality. Postoperative radiographs were assessed for frequency and time of appearance of peri-prosthetic bone remodeling including spot welds, cortical hypertrophy and pedestal formation. All patients were examined by a modified Harris Hip Score.

Results: The proximal canal shape and bone quality were similar in both groups. There was no difference in the frequency of spot welds at 1 year and 2 years. Spot welds were mainly located in Gruen zone 1. Cortical hypertrophy was greater (p < 0.05) at 6 months, 1 year and 2 years with the metaphyseal fit stem. Cortical hypertrophy was found only in Gruen zones 3 and 5. Halo pedestal formation was greater (p < 0.05) at 6 months with the metaphyseal fit stem but not at 1 year and 2 years. Calcar rounding was observed in 25 hips (90.0%) with metaphyseal fit stems and twenty hips (62.5%) with diaphyseal fit stems. At the last follow-up, average HHS was similar (90.6 +/− 1.5 / 91.7 +/− 1.7; metaphyseal / diaphyseal fit stems). No patient developed aseptic loosening.

Conclusions: This is the first study to determine differences in bone remodeling between a metaphyseal and a diaphyseal fixed stem in uncemented THA. After one year, the only significant difference between these two groups was cortical hypertrophy, which was greater in patients undergoing metaphyseal fit stem insertion. Both stem designs demonstrated bone remodeling with no differences in spot welds or pedestal formation. At two years, there was no functional difference between these two patient groups. To further elucidate the relation between radiographic and clinical results, longer term follow-up is required.

The purpose of this study was to determine the effect of positioning (lateral vs. supine) on pulmonary patho-physiology following pulmonary contusion and fat embolism in a canine model of polytrauma. Platelet and neutrophil activation were assessed using flow-cytometry. There were no significant differences between groups in CD62P and CD11/18 MCF (markers of platelet and neutrophil activation, respectively) following fat embolism. However, only animals in the lateral position displayed significant increases in both measures as compared to baseline values. Lateral positioning may exert an early effect on proinflammatory and coagulation activation, and may play a role in the development of acute lung injury.

It has previously been suggested that acute lung injury can be influenced by patient positioning, be it lateral or supine. The purpose of this study was to determine the effect of positioning on pulmonary pathophysiology associated with concomitant pulmonary contusion and fat embolism in a canine model of polytrauma.

Twelve dogs were randomly assigned to one of two surgical positioning groups, lateral and supine. The dogs were subjected to pulmonary contusion by application of force between 200–250 N/m² for thirty seconds in three areas of one lung. Two hours later, fat embolism was induced via reaming of the ipsilateral femur and tibia and cemented nailing. Two hours later, the dogs were sacrificed. For flow-cytometric evaluation of platelet and neutrophil activation, venous blood samples were stained with fluorescence-conjugated antibodies against CD62P and CD11/18, respectively. There were no significant differences between the groups in CD62P and CD11/18 mean channel fluorescence (MCF) following pulmonary contusion and fat embolism. However, only animals in the lateral positioning group displayed significant increases in CD62P and CD11/18 MCF at two hours following fat embolism as compared to baseline values.

Our findings suggest that lateral positioning, autoregulation and preferential blood flow to the contused non-dependent lung may render lung tissue more susceptible to congestion and lead to activation of both platelets and neutrophils. Lateral positioning may have an early effect on activation of the inflammatory and coagulation cascades and may be significant in the development of posttraumatic acute lung injury.

In a meta-analysis of fourteen trials (N=1901 patients) in patients with displaced hip fractures, we identified significant reductions in the risk of revision surgery with internal fixation compared to arthroplasty. A trend towards increased mortality with arthroplasty was identified.

The purpose of this study was to determine the effect of arthroplasty (hemi-arthroplasty, bipolar arthroplasty and total hip arthroplasty) in comparison to internal fixation for displaced femoral neck fractures on rates of mortality and revision surgery

Arthroplasty for displaced femoral neck fractures, in comparison to internal fixation, significantly reduces the risk of revision surgery at the cost of greater infection rates, blood loss and operative time, and a possible increase in early mortality.

Over 220,000 fractures of hip occur per year in North America representing an annual seven billion dollar cost to the health care system. Current evidence suggests internal fixation may reduce mortality risk at the consequence of increased revision rates. A large trial is needed to resolve this issue.

We searched computerized databases (MEDLINE, COCHRANE and SCISEARCH) for published clinical studies from 1969–2002 and identified additional studies through hand searches of major orthopaedic journals, bibliographies of major orthopaedic texts and personal files. We found a non-significant trend toward an increase in the relative risk of dying with arthroplasty when compared to internal fixation (relative risk=1.27, 95% confidence interval, 0.84–1.92, p = 0.25; homogeneity p= 0.45). Arthroplasty appeared to increase the risk of dying when compared to pin and plate, but not in comparison to internal fixation using screws (relative risk= 1.75 vs 0.86, respectively, p< 0.05). Fourteen trials provided data on revision surgery (n=1901 patients). The relative risk of revision surgery with arthroplasty was 0.23 (95% confidence interval, 0.13–0.42, p = 0.0003, homogeneity p = < 0.01).

Using patient-oriented outcome measures, we examined twenty-six patients following surgical repair of clavicular nonunion. Patient satisfaction was high, and there was only a minor degree of residual disability (mean DASH score 14.5, SF-36 scores within normal range). Time from injury to surgical repair did not influence results.

Using modern, patient-oriented limb-specific outcome measures, we sought to determine the effect of time to repair on patient satisfaction following surgical fixation of nonunion of the clavicular shaft.

As measured by the DASH and SF-36, patient satisfaction was high following clavicular nonunion repair with only minor degrees of residual disability. Time to repair did not have a significant effect on outcome.

Previous reports of clavicular nonunion repair have concentrated on radiographic or surgeon-based criteria. Our study shows that successful clavicular nonunion repair effectively restores upper extremity function and general health status to near-normal levels.

We identified twenty-six patients who had undergone open reduction, internal fixation of a nonunion of the clavicular shaft. There were sixteen men and ten women, with a mean age of forty-four years (range thirty to seventy-one years). The mean duration of nonunion was 1.9 years with a range from four months to thirty-one years. All patients underwent fixation with a plate, and 73% of patients also underwent iliac crest bone grafting. Two nonunions required revision surgery for healing: twenty-four healed after the index procedure. We assessed patient outcome using standard history and physical, radiographs, and the DASH and SF-36 outcome instruments. The mean DASH score (0 = perfect, 100 = complete disability, “normal” = 10) was 14.5 (range 0 to 58), indicating good restoration of upper extremity function with mild residual disability. SF-36 scores were within the normal range. There was no significant difference in DASH or SF-36 scores between those fixed “early” (< six months) and those repaired “late” (> six months), p=0.30, p=0.78, respectively.

Using patient-oriented outcome measures, we examined twenty-six patients following surgical repair of clavicular nonunion. Patient satisfaction was high, and there was only a minor degree of residual disability (mean DASH score 14.5, SF-36 scores within normal range). Time from injury to surgical repair did not influence results.

Purpose: The purpose of this study was to compare the biomechanical behavior of locking plates to conventional plate and allograft constructs for the treatment of periprosthetic femoral fractures.

Methods: Twenty synthetic femora were tested in axial compression, lateral bending and torsion to characterize initial stiffness and stiffness following fixation of an osteotomy created at the tip of a cemented femoral component. Stiffness was tested with and without a 5mm gap. Axial load to failure was also tested. Four constructs were tested: Construct A – Synthes locked plate with unicortical locked screws proximally and bicortical locked screws distally; Construct B – Synthes locked plate with alternate unicortical locked screws and cables proximally and bicortical locked screws distally. Construct C – Zimmer cable plate with alternate unicortical non locked screws and cables proximally and bicortical non locked screws distally. Construct D – Zimmer cable plate in same fashion as construct C plus anterior strut allograft secured with cables proximally and distally.

Results: In axial compression, construct D was significantly stiffer compared with all other constructs in the presence of a gap, with no differences between groups without a gap. For lateral bending stiffness, construct D was significantly stiffer than the other groups with and without a gap. In torsional testing, construct D was significantly stiffer than all other constructs in the presence of a gap. With no gap, construct D was significantly stronger than construct B. There were no significant differences between constructs A and B in all testing modalities. Axial load-to-failure ranged from 5561.5 to 6700.2 N. There were no significant differences in axial load to failure.

Conclusions: This study suggests that a single locked plate does not provide the same initial fixation stiffness as a plate-allograft strut construct in the setting of a gapped osteotomy. This may be particularly important in the setting of a comminuted fracture or with bone loss. In these settings, a construct with a lateral plate and an allograft strut placed anteriorly at 90 degrees to the plate, may be optimal.

We report preliminary results from the first, multicenter prospective study designed to define the incidence of symptomatic (Venous Thromboembolism) VTE in patients with isolated leg fractures distal to the knee. Eight hundred and twenty-six enrolled patients have completed three months of follow up. By three months, only seven patients had sustained a symptomatic VTE with no fatal PE. Symptomatic and fatal VTE were infrequent complications after isolated leg fractures distal to the knee without thromboprophylaxis. Routine thromboprophylaxis may not be warranted in isolated leg fractures distal to the knee.

To report results from the first, multicenter prospective study designed to define the incidence of symptomatic Venous Thromboembolism (VTE) in patients with isolated leg fractures distal to the knee.

Symptomatic and fatal VTE are infrequent complications after isolated leg fractures distal to the knee without thromboprophylaxis.

Routine thromboprophylaxis may not be warranted in isolated leg fractures distal to the knee.

From August 2002 to April 2004, one thousand eight hundred and eight consecutive patients with isolated leg fractures distal to the knee were screened for entry at five hospitals in Ontario. Patients with major trauma, active cancer and previous VTE were excluded. Thromboprophylaxis was not allowed. Patients were followed prospectively for three months, with telephone calls at fourteen days, six weeks and three months. Suspected DVT and PE were investigated in a standardized manner.

Eight hundred and twenty-six enrolled patients have completed three months of follow up. The mean age was forty-five years (range sixteen to ninety-three) and 59.5% of this cohort was female. 99% of these fractures were unilateral and 97% were closed. Fractures included: fibula (38%), metatarsal (29%), phalanges (13%), calcaneus, talus or tarsal (10%), tibia (10%) and patella (7%). Only 11% of fractures were surgically treated. 88% of fractures received a cast or splint for a mean duration of 41+/− 20 days. Complete follow-up was available for 97.5% of this cohort. By three months only seven patients had sustained a symptomatic VTE (2 proximal DVT, 3 calf DVT, 2 PE) with no fatal PE-an incidence of 0.9% (95% CI 0.3 to 1.8%).

Funding: This study was funded by a research grant from Pharmacia

The purpose of this study was to evaluate trabecular bone response, at fifty-two week follow-up, to four different synthetic graft materials (CaSO4 and CaSO4 – HA/TCP composites) as compared to autograft in a canine defect model. The group with the highest HA/ TCP proportion had the greatest amount of residual graft material and total mineralized material. Increasing the proportion of HA/TCP reduces the rate of dissolution, and appears to have little effect on bone formation at long term follow-up. This study further suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications.

The purpose of this study was to evaluate trabecular bone response to four synthetic graft materials (CaSO4 and CaSO4 – HA/TCP composites) as compared to autograft in a canine defect model, at long term follow-up.

Both 85% CaSO4 – 15% HA/TCP and 65% CaSO4 – 15% HA/TCP showed bone formation similar to autograft. The group with the highest proportion of HA/TCP lasted longer than the other formulations. The results suggest that increased HA/TCP proportions reduce the rates of dissolution, without compromising bone formation in the current model.

Results suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications.

In this REB-approved RCT, bilateral humeral and femoral cylindrical defects were filled with one of four types of pellets with varying proportions of CaSO4 – HA/TCP, autograft bone, or left unfilled. After sacrifice at six, twelve, twenty-six or fifty-two weeks, defect sites were evaluated histologically for tissue and inflammatory response, area fractions of residual graft material, and bone ingrowth in the defects.

The area of the defect occupied by residual graft material in the group with the highest percentage of HA/TCP was greater than in other composite groups (p< 0.0001). This group contained the greatest amount of total mineralized material (graft material + bone) (p< 0.03. The extent of new bone formation increased from twelve to twenty-six weeks (p< 0.0001). Both 85% CaSO4 – 15% HA/TCP and 65% CaSO4 – 15% HA/TCP showed bone formation similar to autograft.

Funding: Research grant from Stryker Howmedica, Matwah, NJ.

Purpose: The purpose of this study was to examine how the “ideal” tibial nail insertion point varies with tibial rotation and to determine what radiographic landmarks can be used to identify the most suitable rotational view for insertion of a tibial intramedullary nail.

Methods: Twelve cadaveric lower limb specimens with intact soft tissues around the knee and ankle joints were used. A 2.0mm Kirschner wire was placed in the center of the anatomic safe zone and centered on the tibial shaft. The leg was rotated and imaged using a fluoroscopic C-arm until the K-wire was positioned just medial to the lateral tibial spine (defined as the neutral anteroposterior radiograph). The leg was then fixed and radiographs were taken in 5 degree increments by rotating the fluoroscope internally and externally (in total, a 50 degree arc). Following this a second K-wire was placed in 5 mm increments both medially and laterally and the fluoroscope rotated until this second K-wire was positioned just medial to the lateral tibial spine. Radiographs were digitized for measurements.

Results: Given the presence of a 30 degree rotational arc through which the radiograph appeared anteroposterior, it was possible to improperly translate the start point up to 15 mm. Relative external rotation of the image used for nail placement led to a medial insertion site when using the lateral tibial spine as the landmark. A line drawn at the lateral edge of the tibial plateau to bisect the fibula head correlated with an entry point that was central or up to 5 mm lateral to the ideal entry point. The use of a fibula head bisector line avoided a medial insertion point.

Conclusions: Rotation of the tibia may result in up to 15 mm of translation of the start point that may be unrecognized. Relative external rotation of the film used for nail placement leads to medial insertion sites when using the lateral tibial spine as a landmark. The fibula head bisector line can be used to avoid choosing external rotation views and thus avoid medial insertion points.

Purpose: The objective of this study is to investigate the effects of the Reamer-Irrigator-Aspirator (RIA) on fat embolism outcome, as compared to the standard AO reamer, utilizing physiologic parameters as outcome measures.

Methods: All animal procedures were approved by the Animal Care Committee. Fifteen animal experiments were completed. Following anesthesia, each pig was intubated and ventilated. Initial blood samples were analyzed for proper ventilation and acceptable baseline conditions (PaCO2 between 35–40 mm Hg). One third of the pig’s blood volume was withdrawn to simulate hemorrhagic shock. Each animal was kept in a state of hypovolemia for an hour before transfusion and resuscitation. Each pig underwent alternate assignment into either the RIA or AO group. The distal femur was exposed and reamed in a retrograde fashion, followed by cement pressurization with methylmethacrylate. Physiologic measurements included mean arterial pressure (MAP), pulmonary arterial pressure (PAP), partial pressure of arterial oxygen (PaO2), and cardiac output. Upon completion, the animals were euthanized. The data was analyzed using the SPSS statistical program.

Results: One animal in the AO group expired after cement pressurization associated with profound hypotension, pulmonary hypertension and eventual cardiac arrest. There was a statistically significant difference for PaO2 (P = 0.004), cardiac output (P = 0.002), and PAP (P = 0.005) between the AO and RIA groups. That is, by the completion of the experiment the RIA group had higher PaO2, lower PAP, and higher cardiac output measurements as compared to the AO group. There was no statistical significance between the two groups with respect to MAP (P = 0.468).

Conclusions: Using established physiologic parameters, there appears to be a difference between the standard AO reamer and the RIA in terms of fat embolism outcome. The RIA showed a more favorable outcome with respect to PAP, PaO2, and cardiac output. With its simultaneous irrigation and aspiration, the RIA may result in less intramedullary fat displacement into the systemic circulation.

We evaluated the clinical, radiographic, and functional outcome of uncemented total hip arthroplasty (THA) following vascularized fibular grafting for avascular necrosis (AVN) of the femoral head. A group of twenty-two patients who had been converted from a vascularized fibular graft to THA was compared to a similar group of twenty-two patients who had received a THA with no prior graft. The graft group was found to have worse outcomes than the control group as measured by SF-36, and WOMAC scores, as well as a hip score.

These results show that vascularized fibular grafting complicates future THA.

The Purpose of this study was to evaluate the clinical, radiographic, and functional outcome of uncemented total hip arthroplasty (THA) following vascularized fibular grafting for avascular necrosis (AVN) of the femoral head. These results indicate that functional and clinical outcome following post-graft THA is worse than outcome following THA performed as a primary intervention.

Judicious use of the vascularized fibular graft procedure is critical in order to minimize the number of graft failures and avoid the negative outcomes associated with THA after failed vascularized fibular grafting.

Twenty-six hips in twenty-two patients who had a THA following a failed vascularized fibular graft were compared to a group of twenty-three hips in twenty-two age and sex-matched patients who had received a THA with no prior graft (combined mean age: 39.0 yrs). Primary outcome measures included the SF-36 (patient-based general health assessment – total score and physical sub-component) and WOMAC (patient-based arthritis specific score) scores at matched follow up times (mean: 6.2years, range: two to fourteen years). An objective hip score was also used, as were several radiographic variables. The post-graft group had lower SF-36 final scores (p< 0.006), lower SF-36: physical function scores (p< 0.001), and lower WOMAC scores (p< 0.045) than the control group. Post-graft THA was complicated by longer operative time (p< 0.025) and greater subsidence of the femoral prosthesis (p< 0.004) compared to controls. Additionally, the post-graft group had worse hip score values (p< 0.05) than controls.

Vascularized fibular grafting is a commonly used procedure to cure or delay progression of AVN in the hip. Currently this procedure is used for young (< 40 years) patients with hip AVN who are in an early, pre-collapse stage of the disease. Although the efficacy of vascularized fibular grafting has been proven, up to 29% of grafts fail at five years and need to be converted to THA (Urbaniak et al., 1995). This study shows that THA after failed vascularized fibular grafting has a worse outcome than THA as a primary intervention. Therefore judicious use of the graft procedure is critical in order to minimize the number of graft failures and avoid the negative outcomes associated with it.

The purpose of this study was to investigate patient-based functional outcome and objectively measure strength following plate fixation of fractures of both bones of the forearm. Twenty-five subjects were clinically and radiographically reviewed. Strength of elbow flexion, extension, supination, pronation, wrist flex-ion, extension and grip were significantly reduced in the injured arm. (p< 0.01, range 62%–84% of normal). Mean (+/− SE) DASH score was 19.5 +/− 4.0 and eighty-eight percent (22/25) scored good to excellent on the Gartland-Werley scale (mean 4.04 +/− 0.91). No statistical difference in mean maximal radial bow (MRB) or location of MRB between injured and non-injured arm was found.

The purpose of this study was to investigate functional outcome and objectively measure strength following plate fixation of fractures of both bones of the forearm (BBOF).

Anatomic reduction was associated with good to excellent functional outcome. However strength of the elbow, forearm, wrist and grip were significantly reduced in the injured arm.

Despite good to excellent functional outcome following this injury, significant reduction in strength of the upper extremity should be expected, and thus is an area for potential improvement in post-operative care.

Twenty-five subjects (M/F 19/6, mean age 47.6 (range 20–71)) treated with plate fixation for fractures of BBOF were clinically and radiographically reviewed. Mean duration of follow-up was 5.7 years (range 2–13.4 y). Post-operative protocol included short-term immobilization followed by active-assisted ROM and strengthening starting between four and six weeks. Isometric muscle strength was objectively measured with the Baltimore Therapeutic Equipment work simulator (model WS-20). Strength of elbow flexion (72% of non-injured arm, p< 0.0001), elbow extension (84%, p=0.0004), forearm supination (75%, p=0.005), forearm pronation (69%, p< 0.0001), wrist flexion (81%, p=0.009), wrist extension (62%, p< 0.0001) and grip (70%, p< 0.0001) were all significantly reduced in the injured arm. Mean (+/− SE) DASH and Gartland-Werley scores were 19.5 +/− 4.0 (range 0–61) and 4.04 +/− 0.91 (range 0–15) respectively. Eighty-eight percent (22/25) scored good to excellent on the Gartland-Werley scale. No statistical difference in mean maximal radial bow (MRB) between injured and non-injured arm was found (mean +/− SE, 1.42 +/− 0.07 vs 1.58 +/− 0.05 respectively) or in location of MRB (61% vs 59%).

This study was undertaken to assess the contribution of fat embolism (FE) to the development of acute lung injury in the presence of resuscitated hemorrhagic shock. Twenty-seven NZW rabbits were randomly assigned into four groups: resuscitated hemorrhagic shock and FE (HR/FE), resuscitated hemorrhagic shock, FE, and control. FE was induced via intramedullary femoral canal pressurization using a 1–1.5 ml bone cement injection. Only HR/FE animals displayed significant proinflammatory cytokine release as compared to controls. These findings suggest that the combination of resuscitated shock with FE initiates an inflammatory response, which may lead to the development of fat embolism syndrome.

The objective of this study was to assess the contribution of fat embolism caused by intramedullary femoral canal pressurization to the development of acute lung injury in the presence of resuscitated hemorrhagic shock.

Only the animals that underwent resuscitated shock and fat embolism displayed amplified BALF proinflammatory cytokine expression.

These findings suggest that the combination of resuscitated shock with fat embolism initiates an inflammatory response, which may play a role in the development of fat embolism syndrome.

Only HR/FE BALF IL-8 and MCP-1 levels were significantly higher than controls (0.72 ng/ml vs. 0.26ng/ ml, p=0.03; 18.3 ng/ml vs. 2.0 ng/ml, p=0.01, respectively).

Twenty-seven NZW rabbits were randomly assigned into four groups: resuscitated hemorrhagic shock + fat embolism (HR/FE), resuscitated hemorrhagic shock (HR), fat embolism (FE), and control. Shock was induced via carotid bleeding for one-hour prior to resuscitation. For FE induction, the intramedullary cavity was drilled, reamed and pressurized with a 1–1.5 ml bone cement injection. Four hours later, postmortem bronchoalveolar lavage was performed through the right mainstem bronchus. Analyses of bronchoalveolar lavage fluid (BALF) of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) were carried out in triplicate and blinded fashion using the ELISA technique.

Our findings suggest that FE by itself does not initiate inflammatory lung injury, as there were no apparent differences between the control and FE cytokine levels. Only the HR/FE animals revealed elevated levels of pro-inflammatory cytokines in BALF. These findings are in agreement with our previous results, which displayed neutrophil activation only in the HR/FE group.

This study was undertaken to assess the contribution of pulmonary fat embolism caused by intramedullary femoral canal pressurization to the development of acute lung injury in the presence of resuscitated hemorrhagic shock. Twenty-seven NZW rabbits were randomly assigned into one of four groups: resuscitated hemorrhagic shock and fat embolism, resuscitated hemorrhagic shock, fat embolism, and control. Fat embolism was induced via intramedullary cavity with a 1–1.5 ml bone cement injection. Only the animals that underwent resuscitated shock and fat embolism displayed amplified neutrophil activation and alveolar infiltration. These findings suggest that the combination of resuscitated shock with fat embolism initiates an inflammatory response, which may play a role in the development of fat embolism syndrome.

The objective of this study was to assess the contribution of pulmonary fat embolism caused by intramedullary femoral canal pressurization to the development of acute lung injury in the presence of resuscitated hemorrhagic shock.

Only the animals that underwent resuscitated shock and fat embolism displayed amplified neutrophil activation and alveolar infiltration.

These findings suggest that the combination of resuscitated shock with fat embolism initiates an inflammatory response, which may play a role in the development of fat embolism syndrome.

CD11b mean channel florescence was only significantly elevated in the HR/FE group at two and four hours post knee manipulation. Moreover, greater infiltration of alveoli by leukocytes was only significantly higher in the HR/FE group as compared to controls.

Twenty-seven NZW rabbits were randomly assigned into one of four groups: resuscitated hemorrhagic shock + fat embolism (HR/FE), resuscitated hemorrhagic shock (HR), fat embolism (FE), and control. Hypovolemic shock was induced via carotid bleeding for one-hour prior to resuscitation. For fat embolism induction, the intramedullary cavity was drilled, reamed and pressurized with a 1–1.5 ml bone cement injection. For evaluation of neutrophil activation, blood was stained with antibodies against CD45 and CD11b and analyzed with a flow cytometer. Animals were mechanically ventilated for four hours post surgical closure. Postmortem thoracotomy was performed, and three stratified random blocks of each lung were processed for histological examination.

Our findings suggest that FE by itself does not cause lung injury, as there were no apparent differences between the control and FE animals. Only the HR/FE animals revealed a higher number of infiltrating neutrophils into alveolar spaces and greater neutrophil activation.

Fracture of the femoral head usually results from high-energy trauma, particularly motor vehicle accidents. These fractures are often associated with poor functional outcomes. SF-36 and MFA scores were obtained for twenty-five femoral head fractures. The mean SF-36 scores was 57.2 (22.6 to 82) and the mean MFA score was 37.6 (10–72). As expected the scores were negatively correlated (−0.587, p=0.005). The presence of an ipsilateral posterior acetabluar wall fracture negatively affected functional outcome. Fragment excision was associated with a higher functional outcome when compared to internal fixation. Posterior surgical approach resulted in higher scores than patients who underwent an anterior procedure.

Fracture of the femoral head is a rare but severe injury. The purpose of this study is to determine the functional outcome of and prognostic factors associated with femoral head fractures.

Acetabular wall fracture, surgical approach, and method of surgical treatment are prognostic factors of functional outcome as measured by the SF-36 and the MFA.

There is currently no consensus on the management of femoral head fractures and treatment practices have evolved on the basis of a limited series of studies. Functional outcome following femoral head fracture has been evaluated using Epstein’s criteria in several studies, however, only one study has been conducted using a validated outcome measure.

Twenty-five femoral head fractures in twenty-four patients were identified from the trauma and orthopaedic databases of two major trauma centres. The patient with bilateral femoral head fractures was not included in the analysis. After obtaining informed consent, the patients’ medical records were reviewed. Functional outcome was assessed using two validated, patient-based outcome measures, the Short Form (SF)-36 and the Musculoskeletal Functional Assessment instrument (MFA). The average age of the patients was 36.8 (std. dev. 11.1) and the mean length of follow-up was 41.4 months (minimum twelve months). Three factors were identified using non-parametric analysis that significantly affected the functional outcome scores:

The presence of an ipsilateral posterior acetabluar wall fracture negatively affected functional outcome (p=0.08).

5207 patients treated for a calcaneous fracture in Ontario between 1993–1999 were identified from population datasets and were reviewed to evaluate regional practice variation and complication rates for operatively and non-operatively managed calcaneous fractures. There was considerable geographic variation in treatment. Individuals in some parts of Ontario were almost eight times more likely to receive operative treatment than others. The majority of calcaneous fractures in Ontario are treated non-operatively, however the large observed practice variation suggests that there is disagreement among treating clinicians. Primary subtalar fusion has a high risk of post-operative infection and should therefore be considered very cautiously.

The purpose of this study was to evaluate regional practice variation and complication rates for operatively and non-operatively managed calcaneous fractures.

The majority of calcaneous fractures in Ontario are treated non-operatively, however the large observed practice variation suggests that there is disagreement among treating clinicians. Primary subtalar fusion has a high risk of post-operative infection and should therefore be considered very cautiously.

Given the observed regional variation in management of calcaneous fractures more work needs to be done to address this issue.

5207 fractures of the calcaneous in Ontario between 1993–1999were identified from population datasets. Regional variations in treatment and complication rates were computed. Multiple linear regression was used to identify factors associated with complications.

There was considerable geographic variation in treatment. Individuals in some parts of Ontario were almost eight times more likely to receive operative treatment than others. General surgeons or general practitioners definitively treated 30% of patients (almost all closed). Overall rate of complications was low, however there was a 13.4 percent infection rate following immediate subtalar fusion. Infection was 5.3% following ORIF and 0.6% following closed treatment. Infection risk was increased in multiple trauma patients and those with open fractures. Subsequent subtalar fusion rates (within the study period) were higher in multiple trauma patients, but were not associated with treatment (open or closed). Amputation was 22.5 times more likely following open calcaneous fractures but the overall amputation rate was only 0.17%. No relationship between surgeon experience and the rate of complications following operative treatment was identified.

The purpose of this study was to determine the effect of positioning (lateral vs. supine) on pulmonary pathophysiology following pulmonary contusion and fat embolism in a canine model of polytrauma. Platelet and neutrophil activation were assessed using flow-cytometry. There were no significant differences between groups in CD62P and CD11/18 MCF (markers of platelet and neutrophil activation, respectively) following fat embolism. However, only animals in the lateral position displayed significant increases in both measures as compared to baseline values. Lateral positioning may exert an early effect on proinflammatory and coagulation activation, and may play a role in the development of acute lung injury.

It has previously been suggested that acute lung injury can be influenced by patient positioning, be it lateral or supine. The purpose of this study was to determine the effect of positioning on pulmonary pathophysiology associated with concomitant pulmonary contusion and fat embolism in a canine model of polytrauma.

Twelve dogs were randomly assigned to one of two surgical positioning groups, lateral and supine. The dogs were subjected to pulmonary contusion by application of force between 200–250 N/m² for thirty seconds in three areas of one lung. Two hours later, fat embolism was induced via reaming of the ipsilateral femur and tibia and cemented nailing. Two hours later, the dogs were sacrificed. For flow-cytometric evaluation of platelet and neutrophil activation, venous blood samples were stained with fluorescence-conjugated antibodies against CD62P and CD11/18, respectively.

There were no significant differences between the groups in CD62P and CD11/18 mean channel fluorescence (MCF) following pulmonary contusion and fat embolism. However, only animals in the lateral positioning group displayed significant increases in CD62P and CD11/18 MCF at two hours following fat embolism as compared to baseline values.

Our findings suggest that lateral positioning, autoregulation and preferential blood flow to the contused non-dependent lung may render lung tissue more susceptible to congestion and lead to activation of both platelets and neutrophils. Lateral positioning may have an early effect on activation of the inflammatory and coagulation cascades and may be significant in the development of posttraumatic acute lung injury.

Little is known about the psychological morbidity associated with orthopaedic trauma. Our study aimed to determine the extent of psychological symptoms and whether patient psychological symptoms were predictive of outcomes following orthopaedic trauma. Overall, trauma patients experienced higher intensity of psychological symptoms than population norms. Psychological symptoms, patient age, and ongoing litigation predicted functional outcomes. Patients may benefit from early interventions by social workers and psychologists to process their psychological states post injury.

Little is known about the psychological morbidity associated with orthopaedic trauma.

Our study aimed to determine the extent of psychological symptoms and whether patient psychological symptoms were predictive of outcomes following orthopaedic trauma.

All patients attending ten orthopaedic fracture clinics at three University-affiliated Hospitals were approached for study eligibility. All consenting patients would be requested to complete a baseline assessment form, a 90-item symptom checklist-90R (SCL-90R), and the Short-Form–36. The SCL-90R constitutes nine dimensions (Somatization, Obsessive-compulsive, Interpersonal sensitivity, Depression, Anxiety, Hostility, Phobic anxiety, Paranoid ideation, Psychoticism) and three global indices (Global severity index, Positive symptom distress index, positive symptom total). We conducted regression analyses to determine predictors of quality of life among study patients.

Of two hundred and fifteen patients, 59% were male at a mean age of 44.5 years. Over half of patients had lower extremity fractures. Trauma patients experienced greater psychological symptoms than population norms. Overall, trauma patients experienced higher intensity of psychological symptoms than population norms. Patient functional outcomes were predicted by patient age, ongoing litigation, and Positive Symptom Distress. This model predicted 21% of the variance in patient function. Patient somatization was an important psychological symptom resulting in increasing intensity of symptoms. Smoking, alcohol, open fracture, surgeons’ perception of technical outcome, level of education, and time since injury were not predictive in this model.

Psychological symptoms, patient age, and ongoing litigation predicted functional outcomes. Patients may benefit from early interventions by social workers and psychologists to process their psychological states post injury.

Funding: This study was funded in part by research grants from AO North America and Regional Medical Associates, McMaster University. Dr. Bhandari was funded, in part, by a 2004 Detweiler Fellowship, Royal Colleges of Physicians and Surgeons of Canada. Dr. Busse is funded by a Canadian Institutes of Health Research Fellowship Award.

This study investigated the effect presence, method, and timing of fixation of femoral shaft fractures have on the morbidity and mortality of patients with pulmonary contusion.

In the multiply-injured patient with femoral shaft fractures, early (< 24 hours) fracture stabilization with closed, reamed, statically-locked intramedullary nailing has been shown to decrease morbidity and mortality. Controversy exists as to whether such treatment compromises the outcome in patients that have significant co-existing pulmonary injury. This study is the first to specifically investigate the sub-group of patients that have pulmonary contusion.

A retrospective review of patients presenting to a Level One trauma center from 1990 to 2002 with pulmonary contusion identified three hundred and twenty-two cases. Patient characteristics of age, sex, GCS, ISS, AIS, presence of femoral shaft fracture, method and timing of treatment of femoral shaft fracture, and presence of other pulmonary injuries were recorded, as were the outcomes of pulmonary complications (acute lung injury (ALI), ARDS, fat embolism syndrome, pulmonary embolism, and pneumonia), days on ventilatory support, days in the intensive care unit and ward, and death.

There were no significant differences in the patient characteristics between groups with and without femoral shaft fracture. Except for an increased likelihood of the femoral shaft fracture group having ALI (RR 1.11), there were no significant differences in outcomes between the femur fracture/non-femur fracture groups. As well, there were no significant differences in outcomes between the groups that had fracture fixation before or after twenty-four hours or had the fracture fixed with or without intramedullary nailing.

The presence, method, and timing of treatment of femoral shaft fractures do not increase the morbidity or mortality of trauma patients that have pulmonary contusion.

Purpose: Endoprosthetic reconstruction of the distal femur is the preferred approach for patients undergoing resection of bone sarcomas. The traditional How-medica Modular Resection System, using a press-fit stem (HMRS or Kotz prosthesis, Stryker Orthopaedics, Mahwah, New Jersey, USA) has shown good long-term clinical success, but has also been known to incur complications such as stem fracture. The Restoration stem, as a part of the new Global Modular Resection System (GMRS, Stryker Orthopaedics, Mahwah, NJ, USA), is currently proposed for this same application. This stem has a different geometry and provides the advantage of decreased risk of fracture of the component. The goal of this study was to compare the HMRS and Restoration press-fit stems in terms of initial mechanical stability.

Methods: Six matching pairs fresh frozen adult femora were obtained and prepared using a flexible canal reamer and fitted with either a Restoration or HMRS press-fit stem distally. All constructs were mechanically tested in axial compression, lateral bending, and torsion to obtain mechanical stiffness. Torque-to-failure was finally performed to determine the offset force required to clinically fail the specimen by either incurring damage to the femur, the stem, or the femur-stem interface.

Results: Restoration press-fit stems results were: axial stiffness (average=1871.1 N/mm, SD=431.2), lateral stiffness (average=508.0 N/mm, SD=179.6), and torsional stiffness (average=262.3 N/mm, SD=53.2). HMRS stems achieved comparable levels: axial stiffness (average=1867.9 N/mm, SD=392.0), lateral bending stiffness (average=468.5 N/mm, SD=115.3), and torsional stiffness (average=234.9 N/mm, SD=62.4). For torque-to-failure, the applied offset forces on Restoration (average=876.3 N, SD=449.6) and HMRS (aver-age=690.5 N, SD=142.0) stems were similar. There were no statistical differences in performance between the two stem types regarding axial compression (p=0.97), lateral bending (p=0.45), or torsional stiffnesses (p=0.07). Moreover, no differences were detected between the groups when tested in torque-to-failure (p=0.37). The mechanism of torsional failure for all specimens was “spinning” (i.e. surface sliding) at the femur-stem interface. No significant damage was detected to any bones or stem devices.

Conclusions: These results suggest that the Restoration and HMRS press-fit stems may be equivalent clinically in the immediate post-operative situation. Funding: Commerical funding Funding Parties: Stryker Orthopaedics

Fifty-five patients undergoing isolated acetabular revisions in fifty-seven hips were available for review. In thirty-three of fifty-seven hips there was no significant acetabular deficiency; of the remaining twenty-four hips twenty underwent allograft reconstruction and four autogenous bone grafting. Mean follow-up was four years with a range of three to seven years; there have been no femoral loosening, and three further surgical procedures for hip instability. All acetabular components at last review were soundly fixed with the exception of one patient who underwent excision arthroplasty at twelve months for deep infection.

The purpose of this study was to review the functional outcome and the fate of the femoral stem and revised acetabular component following isolated ace-tabular revision.

Findings of the current study demonstrate that isolated acetabular revision does not compromise the final functional nor radiographic outcome in acetabular revision in appropriately selected patients; the fate of the femoral component is not adversely influenced by this procedure.

There is no need to remove the femoral component at the time of acetabular revision if the femoral component is well fixed and stable by pre- and intra-operative assessment.

Prospectively entered data on fifty-seven hips (fifty-five patients) who have undergone isolated acetabular revision without femoral revision was available for review. All patients were assessed pre-operatively and post-operatively on an annual basis by means of physical examination, x-ray, SF-36 and WOMAC questionnaires.

In thirty-three of fifty-seven hips there was no significant acetabular deficiency; of the remaining twenty-four hips, one had a segmental defect, thirteen had a cavitary defect and ten had a combined segmental and cavitary defect. Osteolysis existed in the proximal femur of two hips.

Bone grafting in twenty-four hips consisted of morselized allograft in nine; combined structural and morselized allograft used in eleven and autogenous bone used in four acetabular defects. Autogenous bone grafting was done in two femoral osteolytic lesions.

Mean follow-up was four years with a range of three to seven years. The mean duration of arthroplasty prior to revision was fourteen years (range four to twenty-three years).

There were no nerve palsies, vascular injuries or intra-operative fractures in this patient group. All ace-tabular components at latest review were soundly fixed with the exception of one patient who underwent excision arthroplasty at twelve months for deep infection. Twenty-one of the twenty-four hips with bone grafting demonstrated positive radiographic signs of incorporation; the remaining threehips have a stable interface but no evidence of bone ingrowth. Three of the fifty-seven hips presented with hip dislocations after revision arthroplasty; two were managed by closed reduction; the third by open reduction and soft tissue repair.

The purpose of this study was to evaluate trabecular bone response to four different synthetic graft materials (CaSO₄ and CaSO₄ – HA/TCP composites) as compared to autograft in a canine defect model. The group with the highest HA/TCP proportion (and the lowest CaSO4 proportion) had the greatest amount of residual graft material and total mineralized material (p< 0.05). Increasing the proportion of HA/TCP reduces the rate of dissolution, and appears to have little effect on bone formation. This study suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications.

Calcium sulfates and phosphates have become popular clinically for use as bone graft substitutes, however, their in-vivo performance has not been well characterized. The purpose of this study was to evaluate trabecular bone response to four synthetic graft materials (CaSO₄ and CaSO₄ – HA/TCP composites) as compared to autograft in a canine defect model.

Both 100% CaSO₄ and the 3 CaSO₄– HA/TCP formulations showed good bone formation. The group with the highest proportion of HA/TCP lasted longer than the other formulations, suggesting increased HA/TCP proportions reduce the rates of dissolution, without compromising bone formation in the current model.

Results suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications.

In this REB-approved RCT, bilateral humeral and femoral cylindrical defects were filled with one of four types of pellets with varying proportions of CaSO₄ – HA/TCP, autograft bone, or left unfilled. After sacrifice at six or twelve weeks, defect sites were evaluated histologically for tissue and inflammatory response, area fractions of residual graft material, and bone ingrowth in the defects.

The area of the defect occupied by residual graft material in the group with the highest percentage of HA/TCP was greater than in other composite groups (p< 0.0006). At twelve weeks, this group contained more total mineralized material (graft material + bone) (p< 0.005). The extent of new bone formation was not different among the composite groups at either time-point, but all showed more bone formation than the empty defect.

Funding: This study was funded by a research grant from Stryker Howmedica, Matwah, NJ.

Revision hip arthroplasty does not bring to the patient the same degree of benefit as the primary operation. We compared two hundred and thirteen patients undergoing revision arthroplasty with five hundred and forty-seven patients undergoing primary total hip replacement. The complication rate in the revision arthroplasty group was approximately twice as high in the primary group (p< .05) primarily as a result of postoperative dislocation. Both groups of patients had a statistically significant improvement between their pre- and postoperative WOMAC and SF-36 physical scores; however, there was also a statistically significant difference in outcome when the two groups were compared, with primary patients having significantly improved WOMAC and SF-36 physical scores.

To compare the outcomes between primary and revision total hip arthroplasty patients at one institution with regard to demographics, complication rates and functional outcome.

Revision hip arthroplasty does not bring to the patient the same degree of benefit as does the primary operation. The reason for this is multi-factorial and includes a higher complication rate and lower functional outcome.

Further study of the problems associated with revision total hip replacement especially focused on complication rates would appear to be warranted.

All patients were entered prospectively in a database and were assessed by means of physical examination, radiographs, SF-36 and WOMAC questionnaires. Patients were followed for a minimum of two years with a range of two to five years. Patients were seen on an annual basis.

Five hundred and forty-seven patients underwent primary total hip replacement and two hundred and thirteen patients underwent revision total hip replacement. 53.4% of patients undergoing primary and 52% of patients undergoing revision arthroplasty were female. Mean age at primary hip replacement 61.8 years, revision hip replacement 67.1 years. Post-operative complication rate was 7.6% in primary patients and 14.7% in revision patients (p< .05); there was no statistically significant difference between the two groups with regard to intra-operative fracture, implant loosening or postoperative infection; there was a statistically significant difference in terms of dislocation with 0.8% of primary arthroplasties and 5.6% of revision patients sustaining at least one dislocation following their surgery (p< .01). Both groups of patients had a statistically significant improvement between their pre- and post-operative WOMAC and SF-36 physical scores (p< .0001); however, there was also a statistically significant difference in outcome when the two groups were compared with primary patients having significantly improved WOMAC scores (p< .0001) and significantly improved SF-36 physical scores (p< .0001).