We have undertaken a series of clinical trials over the last 20 years to look at different bearing surface combinations in young adults. We continue to follow these patients well beyond the planned duration of the trials and new information is constantly becoming available. The first trial compared ceramic-on-ceramic with ceramic-on-standard-polyethylene. These patients have now been followed for 20 years with significant wear in the polyethylene group but virtually identical revision rates. The second trial ceramic-on-ceramic, cobalt-chrome-on-standard-polyethylene and cobalt-chrome-on-cross-linked-polyethylene. In this group the ceramic-on-ceramic patients have the lowest revision rate; the ceramic-on-polyethylene group demonstrates a lower wear rate than cobalt-chrome-on-polyethylene. The third trial looks at cobalt-chrome versus zirconium on either cross-linked polyethylene or conventional polyethylene. At 10 years there remains no evidence of improved performance from the zirconium surface as compared to cobalt-chrome. The cross-linked polyethylene group is clearly outperforming the conventional polyethylene in terms of wear rate but at 10 years the revision rates remain the same in all groups. Cross liked polyethylene appears to be the major determining factor in prosthetic longevity and appears to be more important than the counter face material.

A randomized trial was designed to compare the outcome of ceramic-on-ceramic with ceramic on conventional polyethylene. These patients have been followed for 15 years.

58 hips in 57 patients under 60 years of age were randomized into one of two groups. Patients were blinded to the type of hip they received. Both groups of patients were treated routinely with prophylactic peri-operative antibiotics and low molecular weight Heparin. All patients were seen at six weeks, three months and annually after surgery. Clinical and radiologic assessment was carried out at each visit.

Fifty-eight hips were available for analysis, 28 in the CoP group and 29 patients in the CoC group. Mean age of both groups was less than 45 years.

There were seven revisions (16%) among the 58 patients enrolled in the study. In the CoP group four patients underwent revision with head and liner exchange for eccentric polyethylene wear 16 years post-implantation. In the CoC group one patient had a cup revision at 15 years for acute aseptic instability of the acetabulum; two additional patients in the CoC group had femoral head exchange, one for fracture and one for trunnion corrosion. Both occurred 14 years after the index surgery.

Functional outcome scores showed no difference between the two groups at 15 years. Radiographically there was a statistically difference in wear between the two groups.

This study demonstrates that both ceramic-on-ceramic and ceramic-on-polyethylene produce satisfactory functional results with low revision rates in young patients.

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.

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.

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.

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.

The incidence of cervical spine injuries associated with facial fractures varies from study to study. The presence or absence of a cervical spine injury has important implications in trauma patients, influencing airway management techniques, choice of diagnostic imaging studies, surgical approach and timing for repair of concomitant facial fractures. There is general agreement that immediate management of cervical spine injuries is mandatory to prevent further neurological injury. Nevertheless, disagreement exists as to the actual incidence of cervical spinal trauma in conjunction with various facial fracture patterns. The purpose of this study was to review the incidence of cervical spine injury associated with various upper, middle and lower one-third facial fractures presenting to St. Michael's Hospital Regional Trauma Centre. A retrospective chart review was performed of patients presenting to the Trauma Service at St. Michael's Hospital from 1 January 1993 to 31 December 2003 inclusive. The data from this 10 year time span revealed a total of 124 patients with cervical spine injuries drawn from a cohort of 3,356 patients with craniomaxillofacial fractures. The overall incidence of cervical spine injury was 3.7%. Isolated upper 1/3 facial and skull fractures accounted for 1,711 of the patients and were associated with cervical spine injury in .53% of cases, while isolated middle 1/3 facial fractures were seen in 1,154 patients and were associated with a 1.13% rate of cervical injuries. The largest rate of association for cervical spine injury and isolated fractures was seen with lower 1/3 facial fractures at 1.51%. In contrast, combined facial fracture patterns involving two or more facial thirds accounted for the great majority of cervical spine injuries occurring at an incidence of 7.1%. The implications for trauma assessment, diagnosis and treatment of these injuries are reviewed.

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.

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.

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.

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.

Total hip replacement in the young active patient remains one of the major challenges in orthopaedics today. The use of ultra high molecular weight (UHMW) polyethylene acetabular liners is known to cause polyethylene wear related osteolysis, the major limiting factor in its use in the younger active patient. Modern alumina ceramic articulations have been developed in order to reduce wear and avoid polyethylene debris. This prospective randomized long-term study aims to compare the outcome between an alumina ceramic-on-ceramic (CC) articulation with a ceramic on UHMW polyethylene articulation (CP). In the younger active patient, is one option superior to the other with regard to patient satisfaction, osteolysis and implant longevity?

56 hips in 55 patients with mean age 42.2 (range 19–56) each received uncemented components (Wright Medical) and a 28mm alumina head with acetabular liner selected via sealed envelope randomization following anesthetic induction. Subsequent regular clinical and radiologic follow up measured patient outcome scores and noted any radiological changes.

26 CP hips and 30 CC hips were evaluated. One failure required revision in each group. Mean St Michael’s outcome score for each group with up to 10 years follow-up (median 8 years, range 1–10) was 22.8 and 22.9 respectively (p=0.057). Radiographs with a minimum 5 years post-operative follow-up were analyzed in 42 hips (23 CC and 19 CP). Radiolucency of all 3 acetabular zones was identified in one of the CP hips. There was no evidence of osteolysis or loosening identified in the remaining hips. The mean time of wear measurement for the CC group was 8.3 years (SD 1.3, Range 4.8–10.1 years) and for the CP group was 8.1 years (SD 0.9, Range 6.1–9.2 years)(p=0.471). Wear was identified in all but one of the CP replacements but only 12 of 23 CC articulations. The mean wear for the CC group was 0.14 mm (SD 0.16, Range 0–0.48 mm) and for the CP group was 0.89 mm (SD 0.6, Range 0–2.43 mm)(p< 0.001). Extrapolating the annual wear rate from these figures, the respective wear is 0.02mm for the CC group compared to 0.11mm per year for the CP group.

To our knowledge this is the first long term randomized trial comparing in vivo ceramic-on-ceramic with ceramic-on-conventional polyethylene hip articulations. Other than significantly greater wear in the polyethylene group there was no significant difference in long-term outcome scores between the two groups with up to 10 years of follow-up. The use of a ceramic-on-ceramic bearing is a safe and durable option in the young patient avoiding the concerns of active metal ions and osteolytic polyethylene debris. These patients remain under review.

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.

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 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.

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.

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.

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: 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.

Thirty total hip replacements in twenty-eight patients in which a Zirconia/Polyethylene articulation was utilized were compared to a control group undergoing total hip replacement utilizing Cobalt-Chrome/Polyethylene articulation. These patients were matched for gender, BMI and pre-operative diagnosis.

At nine years after implantation there was no difference in the functional outcome between the two groups and no difference in liner wear rate on x-ray (Livermore technique). There was a 27% revision rate in the Zirconia group compared to the 11.5% revision rate in the Cobalt-Chrome group.

Bearing surfaces require long- term clinical follow-up to validate in vitro performance.

To determine the benefit of Zirconia on polyethylene versus cobalt-chrome on polyethylene in total hip articulation.

Zirconia offers no advantage over a cobalt-chrome head in decreasing in vivo polyethylene wear at ten- year follow-up.

Newer bearing surfaces require long- term clinical follow-up to validate in vitro laboratory performance.

All primary total hip replacements at this institution are entered prospectively in a database and are assessed on an annual basis. All patients in this study were followed for a mean of nine years with a range of six to thirteen years.

Thirty cementless total hip arthroplasties were performed in twenty-eight patients utilizing a Zirconia head coupled with a polyethylene acetabular component. Twenty-six hips have been followed for a mean of nine years. These were matched to a control group of twenty-six hips in twenty-six patients utilizing a cobalt-chrome head coupled with an identical polyethylene liner followed for a mean of ten years (range five to fourteen years). There was no functional difference in outcome at nine years between the two groups utilizing the Livermore technique there was no difference in the liner wear rate between the two patient groups. However, seven hips (27%) of the Zirconia group required revision due to loosening and/or extensive osteolysis around the cup and only three hips (11.5%) required revision in the cobalt-chrome group. Our study demonstrates that although changes in component designs and materials may offer theoretical advantages over current components their effect in vivo remains questionable.

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.

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.

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.

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.

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.

Purpose: This cadaveric study examines how changes in femoral entry point for intramedullary instrumentation of total knee replacements affects femoral component positioning.

Methods: Twelve cadaveric lower limb specimens with intact hip, knee and ankle joints were obtained. Total knee navigation instrumentation was secured. Anatomical landmarks required for axes generation were obtained. An initial entry point was made at the center of the distal femur. An intramedullary rod was the introduced into the femur. Five and seven degree cutting blocks were placed onto the rod and positioned against the distal femur with the rotation parallel to the epicondylar axis. The navigation system was then used to generate a varus/valgus angle and flexion/extension angle with respect to the previously generated femoral mechanical axes. This allowed determination of an angle at which the distal femoral cutting block would need to be set to make a neutral distal femoral cut. The guide rod was removed and reinserted five times and measurements recalculated. Data was then collected with entry points 5mm medial, 5mm anterior and 5mm medial and anterior to the initial entry point.

Results: There was no significant difference in varus/ valgus angle with a central compared with 5mm anterior entry point and no difference with a 5mm medial versus 5 mm medial and anterior entry point. The valgus angle required to give a neutral distal femoral cut with a central entry point was 4.98o (SD 0.91o; range 3.5o–6.0o). The valgus angle for a 5mm medial entry point was 6.92o (SD 0.97o, range 5.5o–8.0o). With regards to the sagittal plane a 5mm anterior translation of the entry point changed the flexion/extension angle by 1.58o (SD 0.52o, range 0.5o–2.5o).

Conclusions: Small changes in the entry point can significantly affect component alignment. When moving more medial with the entry point a more valgus angle is required for the cutting block. An entry point at the deepest point of the trochlea may be more reproducible than an anteromedial one but requires a valgus cutting block closer to 5 degrees.

Funding : Commerical funding

Funding Parties : Stryker

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.

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.

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).

The purpose of this study was to determine which activities are important to patients and to determine the severity of those problems. The five most important activities were walking outside, driving, walking indoors, stair climbing and daytime pain. Importance of these did not change postoperatively. The five most severe problems causing limitation were a limp, stiffness, loss of energy, daytime pain and locking. All these activities become statistically less severe over twenty-four months. Activities that are important to patients are different than the problems that are ranked by severity. Surgeons can educate patients that the severity of problems do improve over time following TKA.

The objectives of this study were:

to determine the five most important activities and five most severe problems for patients prior to total knee arthroplasty (TKA) using the Patient Specific Index (PASI) and

Activities that are most important to patients are different than problems that patients find severe. Important activities remain important over time. Severe problems become less severe over time.

Functional activities and PASI scores improve after TKA. Surgeons can educate patients that the problems they find most severe preoperatively do improve over time following TKA. Important activities remain important.

Patients scheduled for elective primary (or revision) TKA at two tertiary care teaching hospitals were enrolled in the study, excluding those not fluent in English and those undergoing TKA for a tumour, acute fracture, or an infection of the prosthesis. Patients completed the PASI pre-operatively, six, twelve and twenty-four months post-operatively.

One hundred and nineteen subjects were enrolled, nineteen were excluded. The five most important activities (ten- point scale, ten is most important) preoperatively were (mean; 95% CI): walking outside (6.25; 6.23–6.27), driving (6.17; 6.12–6.22), walking indoors (6.14; 6.12–6.16), climbing stairs (6.12; 6.10–6.14), and daytime pain (5.84; 5.81–5.87). These activities were not statistically less important over time. The most severe problems were limping (4.81; 4.77–4.85), stiffness (4.59; 4.56–4.62), lack of energy (4.51; 4.47–4.55), daytime pain (4.46; 4.43–3.39) and locking (4.38; 4.27–4.49). These were significantly less severe at twenty-four months (p < .001).

This study (n=126, mean age=68.8 years, males=62) evaluated pre-operative WOMAC pain and physical function, age, gender, general health status, revision severity classification, number of revisions, comorbidity and unilateral vs. bilateral surgery as predictors of WOMAC pain and physical function at twenty-four months post revision hip arthroplasty. Pain improved from 9.3 to 3.6 and physical function improved from 35.4 to 17.1. No factors were predictive of patient function. Decreased pain was predicted by less pain pre surgery (p=0.01) and being male (p=0.04).

To determine if pre-operative WOMAC pain and physical function, age, gender, general health status (SF-36), revision severity classification, number of revisions, comorbidity and unilateral vs. bilateral surgery are predictive of WOMAC pain and physical function at twenty-four months post revision hip arthroplasty.

Physical function at twenty-four months is not independently predicted by the pre-treatment factors evaluated in this study. Male patients with less pain pre surgery and little comorbidity have less pain post surgery.

With the exception of pre-treatment pain, the pre-treatment factors tested in this study provide minimal guidance in identifying factors that might be modified to enhance patient outcome.

This prospective cohort study included one hundred and twenty-six patients (mean age=68.8 years, males: females=62:64) who had revision for other than infection or peri-prosthetic fracture. On average from pre-surgery to twenty-four months post-surgery, WOMAC pain improved 9.3 to 3.6 and physical function improved from 35.4 to 17.1. In univariate analysis (t-test, p< 0.05), males tended to have better function (19.6 vs. 14.7) and reported less pain (4.4 vs. 2.8). No other factors were significant in univariate analysis. None of the a priori factors noted above were independently predictive of patient function at twenty-four months in the multivariate model (F=2.06, p=0.04, R²=0.16). Decreased pain with activity at twenty-four months independently was predicted by having less pain pre surgery (p=0.01), being male (p=0.04) and having fewer comorbidities (p=0.07) in the multi-variate model (F=2.9. p=0.004, R²=0.21).

Funding: This work was supported by a grant from The Arthritis Society

Introduction and Aims: Open femoral fracture is a serious injury. We have asked the question: do open femur fractures in polytrauma patients correlate with higher injury severity scores, increased length of stay and higher mortality rates than in closed femur fracture polytrauma patients.

Method: We undertook a retrospective review of a prospectively gathered trauma database at a Level 1 trauma centre. We identified multiple-injured patients with femur fractures who presented in a 36 month period. The cases were divided into 2 groups; open femur fractures (n=33) and closed femur fractures (n=80). Data was collected on demographics, precipitating event, length of stay spent in the ICU, number of associated injuries, ISS, AIS for affected systems, number of femoral surgeries and disposition. Data was analyzed using parametric statistical tests with a significance level of 0.05.

Results: Our analysis revealed that an average, patients in the open femur fracture group spent 8 + 9 days in ICU, sustained 4 + 1 associated injuries, underwent 2 + 1 femoral surgeries, had an ISS of 29 + 13, and died of their injuries in 30.3% of cases. Patients in the closed femur fracture groups spent 8 + 9 days in ICU, sustained 4 + 1 associated injuries, underwent 1 + 1 femoral surgeries, had an ISS of 29 + 14, and died of their injuries in 12.5% of cases. One-way ANOVA showed no statistically significant difference between groups in terms of time spent in ICU, ISS and number of associated injuries. The average number of surgeries was significantly greater in the open femur fracture group (p-value 0.000). A Chi-squared analysis of disposition indicated that patients with femur fractures were more likely to die of their injuries (p-value 0.020).

Conclusions: Findings of the current study demonstrate that while the presence of an open femur fracture does not correlate with an increase in ISS or increase ICU length of stay it may act as a marker for more serious prognosis in polytrauma patients.

Introduction and Aims: To compare the outcomes between primary and revision total hip arthroplasty in patients at one institution with regard to demographics, complication rates and functional outcome. Further study of the problems associated with revision total hip replacement, focused on complication rates, would appear to be warranted.

Method: 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.

Results: Five hundred and forty-seven patients underwent primary total hip replacement and 213 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 post-operative 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 socres (p< .0001).

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

Introduction and Aims: Open femoral fracture is a serious injury. We have asked the question: do open femur fractures in polytrauma patients correlate with higher injury severity scores, increased length of stay and higher mortality rates than in closed femur fracture polytrauma patients.

Method: We undertook a retrospective review of a prospectively gathered trauma database at a Level 1 trauma centre. We identified multiple-injured patients with femur fractures who presented in a 36-month period. The cases were divided into two groups: open femur fractures (n=33) and closed femur fractures (n=80). Data was collected on demographics, precipitating event, length of stay spent in the ICU, number of associated injuries, ISS, AIS for affected systems, number of femoral surgeries and disposition. Data was analysed using parametric statistical tests with a significance level of 0.05.

Results: Our analysis revealed that on average, patients in the open femur fracture group spent eight + nine days in ICU, sustained four + one associated injuries, underwent two + one femoral surgeries, had an ISS of 29 + 13, and died of their injuries in 30.3% of cases. Patients in the closed femur fracture groups spent eight + nine days in ICU, sustained four + one associated injuries, underwent one + one femoral surgeries, had an ISS of 29 + 14, and died of their injuries in 12.5% of cases. One-way ANOVA showed no statistically significant difference between groups in terms of time spent in ICU, ISS and number of associated injuries. The average number of surgeries was significantly greater in the open femur fracture group (p-value 0.000). A Chi-squared analysis of disposition indicated that patients with femur fractures were more likely to die of their injuries (p-value 0.020).

Conclusions: Findings of the current study demonstrate that while the presence of an open femur fracture does not correlate with an increase in ISS or increase ICU length of stay, it may act as a marker for more serious prognosis in polytrauma patients.

Twelve pairs of fresh-frozen, cadaveric femora were harvested. Each right femur was prepared for the cemented insertion of the femoral component of a total hip implant. Left femora served as matched intact controls. Following insertion of the implants, the distal tip of the stem was identified and an oblique osteotomy was made to represent a periprosthetic fracture. Proximally, plates were secured with cables and distally by bicortical screw fixation (c+s). The twelve pairs of femora were randomly divided into three groups: 1. Zimmer Cable-Ready System, 2. AO 4.5 mm broad, LC-DCP, with Wire Mounts and Double Luque Wires, 3. Dall-Miles Cable Grip System. Specimens were mounted and deforming forces were applied to test the biomechanical stiffness of the constructs. Following testing the plate-cable combinations, the proximal cables were removed and replaced with unicortical screws (s+s). Repeat testing was then performed as per the above protocol.

The stiffness of the constructs relative to intact bone decreased (p< 0.05) with fixation utilising cables plus screws (c+s) during four-point bending (69–77%) and offset rotational loading (61–64%). When testing unicor-tical plus bicortical screw fixation (s+s) in these modes, a similar effect was seen. There was no difference between plate systems (ANOVA, p> 0.05). Comparisons of stiffness between cable plus screw combination versus unicor-tical plus bicortical screw combination revealed that the latter method of fixation (s+s) was more rigid (p< 0.05).

Our study showed that the three plate-cable systems displayed similar biomechanical stiffness. In addition, when the cables were replaced proximally with unicortical screws, more rigid fixation was obtained in all but one plane of testing.

We conclude that the method of plate stabilisation by screws or cables is more significant than the type of plate used for periprosthetic fracture stabilisation.

Two hundred and seventeen consecutive patients (238 hips) underwent total hip arthroplasty using the St Michael’s stem and a non-porous screw ring cup. Patients were followed prospectively clinically using the St Michael’s hip score and radiographically. At an average of 11.9 years (10-13.5 years), 55 patients (59 hips) had died, 23 patients (23 hips) were lost to follow-up. The St Michael’s hip score improved from 13.4 pre-operatively to 21.7 (out of a possible 25) at the latest follow-up. Thirty-seven (24%) of the acetabular components have been revised for aseptic loosening and an additional seven components are radiographically loose. No femoral components have been revised. Using Engh’s criteria one femoral component is definitely loose and two femoral components have stable fibrous ingrowth. Significant stress shielding was noticed in 23 hips (17%) without clinical consequences. Minor osteolysis was seen in 13 hips most commonly around the proximal femur and has not caused symptoms. The St Michael’s stem with its large pore size madreporic surface has comparable results to other porous coated stems with smaller pore size.

The St Michael’s stem provided reliable ingrowth and fixation with an acceptable degree of stress shielding. The non-porous screw ring cup had a high failure rate.

An episode of hypotension is common during cemented joint replacement, and has been associated with circulatory collapse and sudden death. We studied the mechanism of hypotension in two groups of six dogs after simulated bilateral cemented arthroplasty. In one group, with no lavage, the insertion of cement and prosthesis was followed by severe hypotension, elevated pulmonary artery pressure, decreased systemic vascular resistance and a 21% reduction in cardiac output. In the other group, pulsatile intramedullary lavage was performed before the simulated arthroplasties. Hypotension was less, and although systemic vascular resistance decreased, the cardiac output did not change. The severity of the hypotension, the decrease in cardiac output and an increase in prostaglandin metabolites were related to the magnitude of pulmonary fat embolism. Pulsatile lavage prevents much of this fat embolism, and hence the decrease in cardiac output. The relatively mild hypotension after lavage was secondary to transient vasodilation, which may accentuate the hypotension caused by the decreased cardiac output due to a large embolic fat load. We make recommendations for the prevention and management of hypotension during cemented arthroplasty.

The hospital records of 222 cases of ipsilateral fractures of the femur and tibia were reviewed, and patients were grouped according to the type of fracture and the method of treatment. Thirty-five per cent of patients required late operation for delayed union or non-union, osteomyelitis, refracture and malunion, regardless of the treatment group. A disturbing factor was the 30% incidence of osteomyelitis in patients treated by fixation of both fractures, almost three times the incidence when only one fracture was fixed. A 30% incidence of delayed union or non-union occurred in patients managed conservatively. Of sixty-three patients personally examined, the worst results found were those following conservative management of both fractures. More use of rigid external fixation and of cast bracing is recommended in the management of the fractured tibia, combined with internal fixation of the femoral fracture. Examination of the knee suggested that, with ipsilateral fractures, disruption of ligaments is a common occurrence and should always be suspected.