Aims

It is unclear whether mortality outcomes differ for patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) surgery who are readmitted to the index hospital where their surgery was performed, or to another hospital.

Aims

Several different designs of hemiarthroplasty are used to treat intracapsular fractures of the proximal femur, with large variations in costs. No clinical benefit of modular over monoblock designs has been reported in the literature. Long-term data are lacking. The aim of this study was to report the ten-year implant survival of commonly used designs of hemiarthroplasty.

There is an increasing incidence of revision for periprosthetic joint infection. The addition of vancomycin to beta-lactam antimicrobial prophylaxis in joint arthroplasty may reduce surgical site infections, however, the efficacy and safety have not been established.

This was a multicenter, double-blind, superiority, placebo-controlled trial. We randomized 4239 adult patients undergoing joint arthroplasty surgery to receive 1.5g vancomycin or normal saline placebo, in addition to standard cefazolin antimicrobial prophylaxis. The primary outcome was surgical site infection at 90-days from index surgery. Perioperative carriage of Staphylococcus species was also assessed.

In the 4113 patients included in the modified intention-to-treat population, surgical site infections occurred in 72/2069 (3.5%) in the placebo group and 91/2044 (4. 5%) in the vancomycin group (risk ratio 1.28; 95% confidence interval 0.94 to 1.73; p value 0.11). No difference was observed between the two groups for primary hip arthroplasty procedures. A higher proportion of infections occurred in knee arthroplasty patients in the vancomycin group (63/1109 [4.7%]) compared with the placebo group (42/1124 [3.7%]; risk ratio 1.52; 95% confidence interval 1.04 to 2.23; p value 0.031). Hypersensitivity reactions occurred in 11 (0.5%) patients in the placebo group and 24 (1.2%) in the vancomycin group (risk ratio 2.20; 95% confidence interval 1.08, 4.49) and acute kidney injury in 74 (3.7%) patients in the placebo group and 42 (2.1%) in the vancomycin group (risk ratio 0.57; 95% confidence interval 0.39, 0.83). Perioperative Staphylococcus aureus carriage was detected in 1089/3748 (29.1%) of patients.

This is the first randomized controlled trial examining the addition of a glycopeptide antimicrobial to standard beta-lactam surgical antimicrobial prophylaxis in joint arthroplasty. The addition of vancomycin to standard cefazolin prophylaxis was not superior to placebo for the prevention of surgical site infections in hip and knee arthroplasty surgery.

The aim of this study was to examine the incidence of obesity in patients undergoing primary total shoulder replacement (TSR) (stemmed and reverse) for osteoarthritis (OA) in Australia compared to the incidence of obesity in the general population.

A 2017-18 cohort of 2,621 patients from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) who underwent TSR, were compared with matched controls from the Australian Bureau of Statistics (ABS) National Health Survey from the same period. The two groups were analysed according to BMI category, sex and age.

According to the 2017-18 National Health Survey, 35.6% of Australian adults are overweight and 31.3% are obese. Of the primary TSR cases performed, 34.2% were overweight and 28.6% were obese. The relative risk of requiring TSR for OA increased with increasing BMI category. Class-3 obese females, aged 55-64, were 8.9 times more likely to require TSR compared to normal weight counterparts. Males in the same age and BMI category were 2.5 times more likely. Class-3 obese patients underwent TSR 4 years (female) and 7 years (male) sooner than their normal weight counterparts.

Our findings suggest that the obese population is at risk for early and more frequent TSR for OA. Previous studies demonstrate that obese patients undergoing TSR also exhibit increased risks of longer operative times, higher superficial infection rates, higher periprosthetic fracture rates, significantly reduced post-operative forward flexion range and greater revision rates.

Obesity significantly increases the risk of requiring TSR. To our knowledge this is the first study to publish data pertaining to age and BMI stratification of TSR Societal efforts are vital to diminish the prevalence and burden of obesity related TSR.

There may well be reversible pathophysiology in the obese population to address prior to surgery (adipokines, leptin, NMDA receptor upregulation). Surgery occurs due to recalcitrant or increased pain despite non-op Mx.

There is growing interest in the peri-operative management of patients with indications for hip and knee arthroplasty in the setting of modifiable risk factors such as morbid obesity, type 2 diabetes mellitus, and smoking. A recent survey of the American Association of Hip and Knee Surgeons (AAHKS) found that 95% of respondents address modifiable risk factors prior to surgery. The aim of this study was to poll Australian arthroplasty surgeons regarding their approach to patients with modifiable risk factors.

The survey tool used in the AAHKS study was adapted for use in the Australian context and distributed to the membership of the Arthroplasty Society of Australia via Survey Monkey.

Seventy-seven survey responses were received, representing a response rate of 64%. The majority of respondents were experienced, high volume arthroplasty surgeons. Overall, 91% of respondents restricted access to arthroplasty for patients with modifiable risk factors. Seventy-two percent of surgeons restricted access for excessive body mass index, 85% for poor diabetic control, and 46% for smoking. Most respondents made decisions based on personal experience or literature review rather than hospital or departmental pressures.

Despite differences in healthcare systems, our findings were similar to those of the AAHKS survey, although their responses were more restrictive in all domains. Differences were noted in responses concerning financial considerations for potentially underprivileged populations. The survey is currently being administered by arthroplasty societies in six other countries, allowing comparison of orthopaedic practice across different healthcare systems around the world.

In conclusion, over 90% of Australian arthroplasty surgeons who responded to the survey address modifiable risk factors prior to surgery.

Obesity is a known risk factor for hip osteoarthritis. The aim of this study was to compare the incidence of obesity in Australians undergoing hip replacements (HR) for osteoarthritis to the general population.

A cohort study was conducted comparing data from the Australian Bureau of Statistics and the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 2017-18. Body mass index (BMI) data for patients undergoing primary total hip replacement and resurfacing for osteoarthritis were obtained from the AOANJRR. The distribution of HR patients by BMI category was compared to the general population, in age and sex sub-groups.

During the study period, 32,495 primary HR were performed for osteoarthritis in Australia. Compared to the general population, there was a higher incidence of Class I, II, and III obesity in patients undergoing HR in both sexes aged 35 to 74 years old. Class III obese females and males undergoing HR were on average 6 to 7 years younger than their normal weight counterparts. Class III obese females and males aged 55-64 years old were 2.9 and 1.7 times more likely to undergo HR, respectively (p<0.001).

There is a strong association between increased BMI and relative risk of undergoing HR. Similar findings have been noted in the United States of America, Canada, United Kingdom, Sweden and Spain. A New Zealand Registry study and recent meta-analysis have also found a concerning trend of Class III obese patients undergoing HR at a younger age.

Obese Australians are at increased risk of undergoing HR at a younger age. A national approach to address the prevalence of obesity is needed.

Aims

The aim of this study was to estimate the 90-day periprosthetic joint infection (PJI) rates following total knee arthroplasty (TKA) and total hip arthroplasty (THA) for osteoarthritis (OA).

Aims

This study aimed to describe the use of revision knee arthroplasty in Australia and examine changes in lifetime risk over a decade.

Aims

Displaced femoral neck fractures (FNF) may be treated with partial (hemiarthroplasty, HA) or total hip arthroplasty (THA), with recent recommendations advising that THA be used in community-ambulant patients. This study aims to determine the association between the proportion of FNF treated with THA and year of surgery, day of the week, surgeon practice, and private versus public hospitals, adjusting for known confounders.

Introduction/Aims

The Exeter Stem can be used with metal femoral head that are made of either cobalt chrome, or stainless steel. The aim of this study was to compare the rates of revision of these two metal femoral head types when used with this femoral component.

INTRODUCTION

Accurate knowledge of knee joint kinematics following total knee arthroplasty (TKA) is critical for evaluating the functional performance of specific implant designs. Biplane fluoroscopy is currently the most accurate method for measuring 3D knee joint kinematics in vivo during daily activities such as walking. However, the relatively small imaging field of these systems has limited measurement of knee kinematics to only a portion of the gait cycle. We developed a mobile biplane X-ray (MoBiX) fluoroscopy system that enables concurrent tracking and imaging of the knee joint for multiple cycles of overground gait. The primary aim of the present study was to measure 6-degree-of-freedom (6-DOF) knee joint kinematics for one complete cycle of overground walking. A secondary aim was to quantify the position of the knee joint centre of rotation (COR) in the transverse plane during TKA gait.

Total Hip Arthroplasty (THA) is a successful operation for the management of end stage hip osteoarthritis (OA) but long term success is limited by wear of the polyethylene bearing surface. The aim of this study was to compare the rate of revision at 15 years in patients <55 who had a THA for OA, and received either cross-linked (XLPE) or conventional non cross-linked polyethylene (non-XLPE).

The study population was all patients with primary THAs undertaken for OA from 1999 to 31 December 2016. Outcomes were determined for all procedures, comparing THA performed with non-XLPE and XLPE and including the effect of age, sex, and reason for revision. The principal outcome measure was time to first revision using Kaplan-Meier estimates of survivorship.

There were 17,869 procedures recorded for younger patients <55 years of age undergoing THA for OA and using either non XLPE or XLPE. There was a fivefold increase in the rate of revision for procedures using non-XLPE after seven years. The 15 year cumulative percent revision of primary THA performed for OA in patients <55 with non XLPE was 17.4% (95% CI 15.5,19.5) and for XLPE was 6.6% (95%CI 5.5,7.8) HR >7 years =5.3, p<0.001. Non-XLPE and XLPE were combined with three different femoral head bearing surfaces: ceramic, metal and ceramicised metal. Within each bearing surface, XLPE had a lower rate of revision than non-XLPE. For the most common head size of 28mm XLPE had a lower rate of revision.

The use of XLPE has resulted in a significant reduction in the rate of revision for younger patients undergoing THA for OA at 15 years. This evidence suggests that longevity of THA is likely to be improved and may enable younger patients to undergo surgery, confident of a reduced need for revision in the long term.

Aims

Femoral stems with exchangeable (modular) necks were introduced to offer surgeons an increased choice when determining the version, offset and length of the femoral neck during total hip arthroplasty (THA). It was hoped that this would improve outcomes and reduce complications, particularly dislocation. In 2010, the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) first reported an increased rate of revision after primary THA using femoral stems with an exchangeable neck. The aim of this study was to provide a more comprehensive up-to-date analysis of primary THA using femoral stems with exchangeable and fixed necks.

Introduction

Dislocation is one of the leading causes of revision after primary total hip arthroplasty (THA). Polyethylene wear is one of the risk factors for late dislocations (>2 years). It can induce an inflammatory response resulting in distension and thinning of the pseudocapsule, predisposing the hip to dislocation. Alternatively, eccentric seating of the femoral head in a worn out socket may result in an asymmetric excursion arc predisposing the hip to impingement, levering out and dislocation. Highly cross linked polyethylene has a significantly lower wear rate as compared to conventional polyethylene. Incidence of late dislocations has been shown to be significantly greater with conventional polyethylene bearings as compared to ceramic bearings. However, there is no literature comparing the risk of dislocation between ceramic- on- ceramic (CoC) bearings with metal/ceramic- on- cross linked polyethylene (M/CoP) bearings and this was the aim our study

Traumatic disruption of the pelvic ring has a high risk of mortality. These injuries are predominantly due to high-energy, blunt trauma and severe associated injuries are prevalent, increasing management complexity. This population-based study investigated predictors of mortality following severe pelvic ring fractures managed in an organised trauma system.

Cases aged greater than 15 years from 1st July 2001 to 30th June 2008 were extracted from the population-based state-wide Victorian State Trauma Registry for analysis. Patient demographic, pre-hospital and admission characteristics were considered as potential predictors of mortality. Multivariate logistic regression was used to identify predictors of mortality with adjusted odds ratios (AOR) and 95% confidence intervals (CI) calculated.

There were 348 cases over the 8-year period. The mortality rate was 19%. Patients aged greater than 65 years were at higher odds of mortality (AOR 7.6, 95% CI: 2.8, 20.4) than patients aged 15–34 years. Patients hypotensive at the scene (AOR 5.5, 95% CI: 2.3, 13.2), and on arrival at the definitive hospital of care (AOR 3.7, 955 CI: 1.7, 8.0), were more likely to die than patients without hypotension. The presence of a severe chest injury was associated with an increased odds of mortality (AOR 2.8, 95% CI: 1.3, 6.1), while patients injured in intentional events were also more likely to die than patients involved in unintentional events (AOR 4.9, 95% CI: 1.6, 15.6). There was no association between the hospital of definitive management and mortality after adjustment for other variables, despite differences in the protocols for managing these patients at the major trauma services (Level 1 trauma centres).

The findings highlight the importance of the need for effective control of haemodynamic instability for reducing the risk of mortality. As most patients survive these injuries, further research should focus on long term morbidity and the impact of different treatment approaches.

Introduction

Sir John Charnley introduced his concept of low friction arthroplasty— though this did not necessarily mean low wear, as the initial experience with metal on teflon proved. Although other bearing surfaces had been tried in the past, the success of the Charnley THR meant that metal-on-polyethylene became the standard bearing couple for many years. However, concerns regarding the occurrence of peri-prosthetic lysis secondary to wear particles lead to consideration of other bearing surfaces and even to the avoidance of cement (although this has proven to be erroneous). Bearing combinations include polymers, ceramic and metallic materials and are generally categorised as hard/soft or hard/hard. In general, all newer bearing surface combinations have reduced wear but present with their own strengths and weaknesses, some of which are becoming more apparent with time.

Bearing surfaces must have the following characteristics: low wear rate, low friction, Biocompatibility and corrosion resistance in synovial fluid.

FAI has been implicated in the progression of osteoarthritis (OA) and early detection may allow for treatment, which can slow or halt progression. FAI is a difficult condition to image and there is little objective evidence about imaging accuracy. We aim to measure the accuracy of five imaging modalities.

Three blinded observers retrospectively reviewed five different modalities from two age and sex matched groups: A patient group referred to the outpatient clinic with a clinical diagnosis of FAI and a control group who had had CT scans of the pelvis for suspected trauma, where the Pelvic scan had been reported as showing no injuries.

The imaging modalities were: Standard x-ray; Antero-Posterior, Lateral; Condition-specific x-ray projections; Dunn view, lateral internal rotation; Standard Computer Tomography (CT) multiplanar reconstruction (MPR); axial, sagittal and coronal; Condition-specific CT MPR; angled axial, angled coronal; 3D modelling; and surface rendered dynamic.

We found marked variations in the sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictiive Value (NPV) for each of the following imaging modalities: Standard X-ray; Sensitivity 51.9; Specificity; 57.1; PPV; 40; NPV; 68.3 Special X-rays; Sensitivity; 66.7; Specificity; 57.1; PPV; 46.1; NPV; 75.7. Standard CT MPR; Sensitivity; 40.7; Specificity; 75.5; PPV; 47.8; NPV; 69.8 Special CT MPR; Sensitivity; 48.1; Specificity; 57.1; PPV; 46.4; NPV; 70.8 Dynamic 3D CT models; Sensitivity; 55.6; Specificity; 69.3; PPV; 42.8; and NPV; 71.8.

The Dynamic 3D CT models (where the observer can manipulate the model in real time three dimension to control the perspective) proved to be the most accurate, closely followed by the special X-Ray views, which were also the most sensitive. The Standard CT MPRs were the most specific but had a low sensitivity.

This is the first study to measure sensitivity, specificity and PPV and NPV for these imaging modalities in FAI. We recommend the use of condition-specific X-Ray views as well as 3D CT Models for optimal imaging accuracy in this condition. Standard X-Ray views and CTs proved less useful.

Delayed union and non-union are complications of fracture healing associated with pain and with functional and psychosocial disability. This study compares the effect on self-reported health outcomes of delayed union or non-union of femoral and tibial shaft fractures treated at two major metropolitan trauma centres in Victoria.

Patients admitted to the Royal Melbourne Hospital and The Alfred with extra- articular femoral and tibial shaft fractures during 2003-2004 and 2005-2006, and followed up by the Victorian Orthopaedic Trauma Outcomes Registry (VOTOR) were included. Hospital medical records were reviewed to identify the outcome of each fracture. Fracture healing was assessed by the need for unplanned revision surgery for delayed union or nonunion, and clinical and radiological evidence of union. Prospectively-gathered VOTOR health outcome measurements included the Short Form 12-Item Health Survey (SF-12), and return to work and pain status at 6 and 12 months post injury.

Of the 520 patients, 260 femoral and 282 tibial shaft fractures were included. In total, 285 fractures progressed to union, 138 fractures developed delayed union or non-union and 119 fractures had an unknown outcome. Factors that were significantly different between the union and delayed union or non-union groups included: fund source, mechanism of injury, other injuries, wound and Gustilo type, and fixation method. On linear regression modelling, an inverse relationship was demonstrated between delayed union or nonunion and the Physical and Mental Component Summary scores of the SF-12. This was statistically significant at both 6 and 12 months post injury unadjusted and adjusted for age, gender and other injuries. On logistic regression modelling, patients with delayed union or non-union showed unadjusted and adjusted risk ratios of 0.85 and 0.82, respectively at 6 months, and 0.82 and 0.76, respectively at 12 months to return to work. Similarly, patients with delayed union or nonunion had unadjusted and adjusted risk ratios of 1.09 and 1.11, respectively at 6 months, and 1.33 and 1.37, respectively at 12 months to have pain. Both were statistically significant at 12 months post injury unadjusted and adjusted for age, gender and other injuries.

Patients with delayed union or non-union of femoral and tibial shaft fractures have poorer physical and mental health at 6 and 12 months post injury. In addition, they are less likely to have returned to work and more likely to still have pain at 12 months post injury.

A key determinant of long-term implant survival following primary TKA is post- operative alignment of the limb and components. The aim of this study was to compare the accuracy of the Vector-Vision CT-free navigation system versus conventional hand-guided TKA by comparing post-operative alignment.

In a retrospective study 51 sets of post-operative radiographs were analysed, 33 computer-guided and 18 hand-guided. A specific protocol for the measurement of post-operative TKA radiographs was outlined and a novel Trigonometric Method (TM) of angle measurement was compared with the traditional Goniometer Method (GM) of measurement.

The standardised protocol was applied to all 51 sets of radiographs. In total, six angles were measured on each radiograph by two independent observers and compared between the computer-guided and hand-guided groups.

A protocol for the measurement of post-operative TKA radiographs was delineated with step-by-step instructions. The TM of angle measurement had a precision of 1.06° compared with 1.5° using the GM. The standard deviation of the TM was significantly smaller than the GM (p=0.033) and the intra-class correlation coefficient (ICC) of the TM was 0.94 versus 0.90 for the GM.

For the Mechanical Axis (MA), 91% of patients in the computer-guided group attained a MA within 180±3o compared with only 78% in the hand-guided group. T he absolute median raw deviation from 180° was 0.8 in the navigated group and 1.9° in the hand-guided group (p=0.029). Thus, the navigated group was associated with significantly less variability about the neutral 180°. For the other five angle measurements, a higher percentage of patients attained a more neutral alignment with computer-guided TKA; however, these did not reach statistical significance

The computer-assisted group demonstrated significantly more neutral alignment following TKA, and this may in turn lead to reduced TKA failure rates and improved implant longevity. In addition, a new TM of angle measurement was found to be more superior in terms of precision in comparison to the traditional method.

As there is currently no evidenced-based and systematic way of prioritising people requiring JRS we aimed to develop a clinically relevant system to improve prioritisation of people who may require JRS. An important challenge in this area is to accurately assign a queue position and improve list management. To identify priority criteria areas eight workshops were held with surgeons and patients. Domains derived were pain, activity limitations, psychosocial wellbeing, economic impact and deterioration. Draft questions were developed and refined through structured interviews with patients and consultation with consultants. 38 items survived critical appraisal and were mailed to 600 patients. Eleven items survived clinimetric and statistical item reduction.

Validation then included co-administration with standardised questionnaires (960 patients), verification of patient MAPT scores through clinical interview, examination of concordance with surgeon global ratings and test-retest.

Ninety-six Victorian surgeons weighted items using Discrete Choice Experiments (DCEs). The DCE scaling generated a scale, which clearly ranked patients across the disease continuum. The MAPT differentiated people on or not on waiting lists (p<0.001), and was highly correlated with other questionnaires, e.g., unweighted-MAPT vs WOMAC (r=0.78), Oxford Hip/Knee (r=0.86/0.75), Quality of Life (r=0.78), Depression (r=0.64), Anxiety (r=0.60), p<0.001 for all. Test-retest was excellent (ICC=0.89, n=90). Cronbachs reliability was also high 0.85. The MAPT is now routinely administered across all Victorian hospitals undertaking arthroplasty where the response rate is generally above 90%. In the hands of clinicians the MAPT has been used to facilitate fast-tracking of patients with the greatest need, monitoring for deterioration in those waiting for surgery or having a trial of non-operative treatment and deferment of surgery for those that may benefit from further non-operative treatments.

The MAPT is short, easy to complete and clinically relevant. It is a specific measure of severity of hip/knee arthritis and assigns priority for surgery. It has excellent psychometric and clinimetric properties evidenced by concordance with standard disease-specific and generic scales and widespread use and endorsement across health services.

Long waiting times and a growing demand on services for joint replacement surgery (JRS) prompted the Victorian Department of Human Services to fund a University of Melbourne/Melbourne Health partnership to develop and implement an osteoarthritis (OA) hip and knee service delivery and prioritisation system for those who may require JRS.

The service delivery model consists of a multidisciplinary team providing, comprehensive early assessment, evidence-based interventions, including support for patient self-management, continuity of care processes, and prioritisation for both surgical assessment and JRS. Prioritisation occurs via clinical assessment and the Hip and Knee Multi-Attribute Prioritisation Tool (MAPT), a patient, clinician, or proxy-administered 11-item questionnaire, resulting in a 100-point scale ranking of need for surgery. The Hip and Knee MAPT was developed using intensive consultation with surgeons, state-of-the-art clinimetrics and with input from patients, hospital management groups. Ninety-six surgeons contributed to the developing the final scoring system.

Over 4000 patients per year are entering the system across 14 hospitals in Victoria. Under the supervision of the orthopaedics unit, musculoskeletal coordinator (MSC), typically an experienced physiotherapist or nurse, as part of the multidisciplinary team, undertakes early comprehensive assessment, referral and prioritisation of patients with hip or knee OA referred to orthopaedic outpatient clinics. In addition, the MSC coordinates the monitoring and management of patients on the orthopaedic surgery waiting list. The processes enable patients who are most needy (via higher MAPT score and clinical assessment) to be fast-tracked to orthopaedic surgery; conversely those patients with lower scores receive prompt conservative management.

Time to first assessment and waiting times to see a surgeon for many patients have reduced from 12+ months to weeks. Patients seen by surgeons are more likely to be ready for surgery and have had more comprehensive non-operative optimisation. Patients placed on the surgical waiting list receive quarterly reassessments and evidence of deterioration is used as a basis for fast-tracking to surgery.

The OWL system is a whole of system(tm) approach informed by patients needs and surgeons needs. Clinicians have developed confidence in the clinical relevance of the MAPT scores. Uptake of the OWL model of care has been very high because it facilitates better care and better patient outcomes.

Hip fracture is a common cause of hospital admission and is often followed by reduced quality of life, or by death. International experiences indicate there are many benefits to be gained from national hip fracture registries. This pilot project aims to implement a hip fracture registry at three sites, a large metropolitan public hospital (Flinders Medical Centre), a large metropolitan private hospital (Epworth HealthCare) and a rural regional hospital (Goulburn Valley Health) to assess the feasibility of establishing a national registry.

Patients undergoing surgery for a hip fracture will be recruited from the three participating hospitals between March and September 2009. A minimum data set will be collected at discharge, from hospital records. Items include patient demographics, fracture descriptors, length of stay, residential status, mobility, health status, surgical details and discharge destination. A phone interview at four months after surgery will measure outcomes by using the Extended Glasgow Outcomes Scale and documenting residential status, mobility, hip pain and readmissions. Re- operations, if any, will be collected. The availability of data from State Health Departments for validation of hospital case data will be reported.

The pilot study is in progress at the time of writing. Ethical approval has been obtained, data collection, transmission and storage systems have been developed and deployed, and case data collection is underway. Case data will be summarised to describe hip fracture at the participating hospitals. Analysis will review the data elements in the pilot data set and assess their priority for inclusion in a national register—taking account of the quality of the data obtained and the time and other resources required for their collection. We will also evaluate the four-month review process. Any potential obstacles to a national registry that are identified during the pilot will be described and ways to overcome them will be proposed.

A national hip fracture registry will improve the quality of care and safety of patients following hip fracture by developing an efficient mechanism to compare and improve the effectiveness of acute health care delivery by all hospitals involved in the management of hip fractures.

Percutaneous cannulated screw placement (PCSP) is a common method of fixation. In pelvic trauma neurovascular structures are in close proximity to the screw path. Pre-operative planning is needed to prevent injury. This study aims to the safety margin and accuracy of screw placement with computer navigation (CAS).

A control had no pathology in the pelvis but CT scans were performed for suspected trauma. The treated group had pelvic and acetabular fractures and were treated with CAS PCSP at our institution. Using a new technique involving CT 3D modelling of the whole (3D) safe corridor, the dimensions of the Posterior elements (PE) of the pelvic ring and the anterior column of the acetabulum (AC) were measured in the control group.

The accuracy of screw placement (deviation between the actual screw and planned screw) was measured in treated patient using a screenshot method and post-operative CTs. There were 22 control patients and 30 treated patients (40 screws).

The mean ± (standard deviation, SD) minimum measurement of the safe corridor at the PE was 15.6 ± 2.3 mm (range 11.6 mm to 20.2 mm) and at the AC was 5.9 ±1.6 mm (range 3.0 mm to 10.0 mm). The mean ± (SD) accuracy of screw placement was 6.1 ± 5.3 mm and ranged from a displacement of 1.3 mm to 16.1 mm. There was a notable correlation between Body Mass Index, duration of surgery and inaccuracy of screw placement in some patients. The largest inaccuracy of screw placement was due to reduction of the fracture during screw insertion, causing movement of the bone fragments relative to the array and therefore also the computerised screw plan.

There were no screw breakages, non-unions, neurological or vascular complications.

CAS PCSP is a safe and accurate technique. However, the safe corridor is variable and often very narrow. We recommend that the dimensions of the safe corridor be assessed pre-operatively in every patient using 3D modelling to determine the number and size of screw that can be safely placed.

Perthes disease often leaves young adults with hip joint incongruency due to femoral head asphericity, (extra-articular extrusion and superior flattening). This causes femoro-acetabular impingement, a reduced range of movement and early degenerative change. We report a novel method for restoration of femoral head sphericity and femoro-acetabular congruency.

Two males (aged 21 and 22 years) presented with groin pain and severe hip stiffness after childhood Perthes disease. Imaging confirmed characteristic saddle shaped deformities of the femoral head, with cartilage loss overlying a central depression in the superior section of the head. A new method of treatment was proposed. Both cases were treated in the same manner.

A surgical dislocation was performed with a trochanteric flip osteotomy. The extra-articular bump was removed with osteotomes and a burr to reduce femoro- acetabular impingement. The sphericity of the femoral head was restored using a HemiCap partial re-surfacing (Arthrosurface, MA, USA). The radius of the implant was selected to match that of the acetabulum. Restoration of the height of the flattened portion of the weight-bearing surface of the femoral head reduces abnormal loading of the acetabular articular cartilage by improving congruency of the joint. Both patients recovered without incident and were mobilised with crutches, restricted to touch weight-bearing for six weeks to protect union of the trochanteric osteotomy.

At a minimum of three year follow-up both patients had sustained improved range of movement, pain and Oxford hip score. Repeated imaging shows no evidence of joint space narrowing or loosening at this stage.

We conclude that this novel treatment functions well in the short term. Further surveillance is on-going to confirm that this treatment results in improved long term durability of the natural hip joint after Perthes disease.

Introduction: Perthes disease often leaves young adults with hip joint incongruency due to femoral head asphericity, (an extra-articular extrusion and a superior flattening). This causes femoroacetabular impingement, a reduced range of movement and early degenerative change. We report a novel method for restoration of femoral head sphericity and femoroacetabular congruency.

Methods: 2 males (21 & 22 years) presented with groin pain and severe hip stiffness after childhood Perthes disease. Imaging confirmed characteristic saddle shaped deformities of the femoral head, with central depression and overlying cartilage loss. A new method of treatment was proposed. Both cases were treated in the same manner.

Results: Using a surgical dislocation with the trochanteric flip osteotomy it was possible to remove the extra-articular bump to reduce femoroacetabular impingement. We found that the sphericity of the femoral head could be restored using a HemiCap partial resurfacing (Arthrosurface, MA, USA). The radius of the implant was selected to match that of the acetabulum.

Restoration of the height of the flattened portion of the weight-bearing surface of the femoral head reduces abnormal loading of the acetabular articular cartilage by improving congruency of the joint.

At a minimum of 3 year follow up both patients had sustained improved range of movement, pain and Oxford hip score. Repeated imaging shows no evidence of joint space narrowing or loosening at this stage.

Conclusion: We conclude that this novel treatment functions well in the short term. Further studies are needed to confirm that after Perthe’s disease this treatment results in improved long term durability of the natural hip joint.

Introduction: Percutaneous cannulated screw placement (PCSP) is a safe method of internal fixation, indicated for pelvic ring fractures. Due to the close proximity of neurovascular structures to the path of the screw placed in either the Posterior elements (PE) or Anterior column (AC), pre-operative planning is needed to prevent injury.

This study aims to develop a pre-operative protocol for the Australian population, regarding the safe number of screws and size of screw that may be placed. Additionally, results from the study may help identify patients at increased risk of injury during PCSP.

Methods: All patients were from the Australian population and had been admitted into the emergency department at The Royal Melbourne Hospital. Control patients had no pathology in the pelvis, while treated group patients had pelvic ring fractures and were treated with PCSP.

Safe corridor measurements of the PE and AC were taken in the control patients. Pelvic CT scans, taken as part of trauma protocol, were reconstructed using 3D modelling and the dimensions of the whole (3 dimensional) safe corridor measured.

The accuracy of screw placement was determined in each treated patient. Accuracy was assessed by the screenshot method, the post-operative CT method or by both methods. In both methods, accuracy was taken as the deviation between the positions of the actual screw and planned screw.

Results: There were 22 control patients and 12 treated patients.

The mean ± (standard deviation, SD) minimum measurement of the safe corridor at the PE was 15.6 ± 2.3 mm (range 11.6 mm to 20.2 mm) and at the AC was 5.9 ±1.6 mm (range 3.0 mm to 10.0 mm).

The mean ± (SD) accuracy of screw placement was 6.1 ± 5.3 mm and ranged from a displacement of 1.3 mm to 16.1 mm.

Conclusion: The minimum dimensions of the safe corridor and the accuracy of screw placement occurred over a wide range. We recommend that dimensions of the safe corridor be assessed pre-operatively in every patient using 3D modelling to determine the safe number and size of screw that can be placed.

Introduction: Dislocation is the most common complication resulting in re-operation following total hip arthroplasty, accounting for 33.5% of revisions. This study investigates the relationship between bearing surface and the risk of revision due to dislocation.

Materials and Methods: Analysis was based on 110,239 primary total hip arthroplasties with a primary diagnosis of osteoarthritis. Data were collected by the Austra-lian Orthopaedic National Joint Replacement Registry from September 1999 to December 2007. The bearing surfaces were: 20627 (18.7%) ceramic-on-ceramic, 14001 (12.7%) ceramic-on-polyethylene, 12208 (11.1%) metal-on-metal, and 62437 (56.6%) metal-on-polyethylene. In 966 (0.8%) hips the bearing surface was unknown.

Results: There were 862 (0.8%) hips revised due to dislocation, with a rate of 0.3 revisions per 100 component years. Survival analysis with an end point of revision due to dislocation was performed. Revision for dislocation is potentially associated with variables other than bearing surface (including age and femoral component head size). Therefore analyses were stratified by femoral head size (≤28mm and > 28mm), and age (< 65 years and ≤65 years). There is a significantly higher rate of revision for dislocation in ceramic-on-ceramic bearing surfaces compared to metal-on-polyethylene bearing surfaces after adjustment for age, sex and head size in the head size < =28mm/Age < 65 group (hazard ratio = 1.53, 95% C.I. = 1.02 to 2.30, p=0.041) and the head size > 28mm/Age > =65 group (hazard ratio = 1.73, 95% C.I. = 1.10 to 2.74, p=0.016).

Discussion: Ceramic-on-ceramic bearing surfaces have a higher risk of revision due to dislocation in the femoral head sizes and ages discussed above, compared with metal-on-polyethylene. Possible mechanisms for this observed difference may include patient selection, the limits to head and liner offset options when using ceramic bearing surfaces or higher rates of revision after dislocation due to ceramic head or liner damage. However our results are based on a seven year follow-up, and higher rates of late dislocation with polyethylene bearings may be observed in association with higher wear rates compared with ceramic liners.

There are several different ways of preparing the femoral canal prior to cementing a hip prosthesis. This study investigated the mechanical strength of the cement-bone interface of four different types of preparation determined by the maximum tensile force required to separate a cemented prosthesis from its cancellous bone origin.

Forty-eight fresh-frozen ox femora were prepared for hip arthroplasty, In a four-way comparison, groups of eleven femora were prepared by irrigation using

syringe injected normal saline;

Specimens were secured to a Material-test System (MTS), and the femoral implant pulled from the femur uni-axially at a rate of 5mm/min. The ‘pull-out strength’ was defined as the maximum tension recorded by the MTS during separation. Cement interdigitation was also inspected for each technique by microscopy of eight bone-implant transverse sections taken from prepared specimens.

Following an analysis of variance and pair-wise Fisher comparison, the average pull-out strength of the cemented prosthesis was significantly higher (P< 0.001) using pulse-lavage brushing (mean 8049.2 N), and pulse-lavage brushing in combination with hydrogen-peroxide soaked gauze (mean 8489.1 N), than with normal saline irrigation (mean 947.1 N) or hydrogen-peroxide soaked gauze preparation (mean 1832.6 N). Prosthesis pull-out strength following pulse-lavage brushing in combination with hydrogen-peroxide soaked gauze was not significantly different (P> 0.05) than preparing with pulse-lavage brushing alone. Low and high power microscopy of specimen transverse sections revealed the greatest levels of cement penetration in specimens prepared using pulse-lavage brushing.

This study demonstrated that one of the most effective preparations of the femoral canal for optimal mechanical fixation between cement and cancellous bone is pulse- lavage brushing. The use of hydrogen-peroxide soaked gauze in femoral canal preparation, either alone or in combination with pulse-lavage brushing, may not significantly improve prosthesis fixation.

Traditionally autologous bone graft is the standard treatment for non-union of fractures. More recently osteo-inductive agents with or without allograft have been utilised. A trial of Autologous Mesenchymal Precursor Cells has been completed at the Royal Melbourne Hospital to investigate their potential for the treatment of nonunion of long bone fractures.

With the approval of the ethics committee at the Royal Melbourne Hospital a human safety trial was commenced for the treatment of fracture non-union. Bone marrow cells were harvested from patients approximately six weeks before surgery and cultured in a laboratory. The cells were expanded in a culture medium. At the time of definitive surgery the stem cells were implanted on a hydroxy apatite/tricalcium phosphate matrix to the non-union site. Any further fixation that was required at the time of the union was performed by the treating surgeon. Investigations were performed at regular intervals to assess for union and for any reaction to the stem cells and growth medium.

The trial has been completed and eleven patients have been entered into the study. There were eight patients with non-union of femoral fractures and four patients with tibial non-unions (one patient with ipsilateral injuries to both bones). The average age was 41.9 years and the mean time to surgery from the initial injury was 15.2 months. Eight patients have united at a mean time of 24 weeks. One is well on the way to union and of the remaining two patients one is listed as uncertain and one a declared non union. The patient who has failed to unite is currently awaiting further surgery. One patient withdrew from the trial after ceasing smoking and finally uniting prior to stem cell implantation. There has been one adverse event with possible infection at a screw site though this was thought not to be related to stem cell therapy.

This is a phase one safety trial of a new development for the treatment of a nonunion of long bone fractures. The results are promising with the regards to achieving bone union without any significant complications. This paves the way for a trial involving allogeneic stem cells.

Computer navigation was introduced in Australia in 2000, initially with the use of pre-operative computer scans and then later with image free systems. In 2003 the AOA – NJRR began collecting data for knee replacement performed with computer navigation.

Meta analysis of the literature has shown better coronal and sagittal plane alignment in total knee arthroplasty performed with computer navigation as opposed to standard instrumented knee replacement. At present, however, there is no data on improved outcomes or reduced revision rates. Information was requested from the AOA – NJRR on the use of computer navigation for both uni-compartmental and total knee replacements. This included numbers of navigated knees done per year as well as revision rates and reasons for revisions of knees performed by computer navigation surgery.

Since data collection began there has been 2,651 computer assisted total knee replacements performed which is 4.1% of the total number of knee replacements in this time period. There has been a steady increase in the last three years in the use of computer navigation. There has been an increased number of computer navigated knees performed in the private hospital sector as opposed to the public hospitals and there is a state by state variation in the uptake of navigation. The revision rate per 100 observed ‘component’ years at three years is 2.8 for non computer assisted and 2.5 computer assisted surgery. This is not statistically significant. There is no difference in the early complication rate leading to revision.

The use of computer navigation could be expected to reduce the long term revision rates of knee arthroplasty due to better alignment and potentially less wear. In the short term there is no significant revision rate between the two methods of performing TKR particularly with regard to infection or fracture

Dislocation is a common reason for revision following total hip replacement. This study investigated the relationship between the bearing surface and the risk of revision due to dislocation. It was based on 110 239 primary total hip replacements with a diagnosis of osteoarthritis collected by the Australian Orthopaedic Association National Joint Replacement Registry between September 1999 and December 2007. A total of 862 (0.78%) were revised because of dislocation. Ceramic-on-ceramic bearing surfaces had a lower risk of requiring revision due to dislocation than did metal-on-polyethylene and ceramic-on-polyethylene surfaces, with a follow-up of up to seven years. However, ceramic-on-ceramic implants were more likely to have larger prosthetic heads and to have been implanted in younger patients. The size of the head of the femoral component and age are known to be independent predictors of dislocation. Therefore, the outcomes were stratified by the size of the head and age.

There is a significantly higher rate of revision for dislocation in ceramic-on-ceramic bearing surfaces than in metal-on-polyethylene implants when smaller sizes (≤ 28 mm) of the head were used in younger patients (< 65 years) (hazard ratio = 1.53, p = 0.041) and also with larger (> 28 mm) and in older patients (≥ 65 years) (hazard ratio = 1.73, p = 0.016).

Aim: To investigate the functional and radiological outcome of shelf acetabuloplasty in adults with significantly symptomatic acetabular dysplasia, with a minimum of a 5 year follow-up.

Material and Methods: 77 consecutive shelf procedures (68 patients) with an average follow-up of 10.9 years (range: 6–14) were reviewed. The Oxford hip score (OHS) was used for clinical assessment. Centre-edge angle (CEA) and acetabular angle (AA) were measured as indicators of joint containment. The severity of osteoarthiritis was based primarily on the extent of joint space narrowing. Survivorship analyses using conversion to THR as an endpoint were performed. Logrank tests were used to compare the survivorship of the shelf procedure against the variables of age, preoperative osteoarthiritis, pre and postoperative AA, CEA angles.

Results: The average age at time of surgery was 33 years (range: 17–60). At the time of the last follow-up, the mean OHS was 34.6 (maximum score: 48). Mean postoperative CEA was 55 (Pre-operatively: 13 degrees) while mean postoperative AA was 31 (Pre-operatively: 48 degrees). Thirty percent of hips needed THR at an average duration of 7.3 years. The survival in the 45 patients with only slight or no joint space narrowing was 97% (CI, 93%–100%) at 5 years and 80% (CI, 56%–100%) at 10 years. This was significantly higher (p= 0.0007) than the survival in the 32 patients with moderate or severe osteoarthiritis, which was 72% (CI, 55%–89%) at 5 years and 29% (CI, 13%–45%) at 10 years. There was no significant relationship between survival and age, pre and postoperative AA, CEA angles (p> 0.05).

Conclusion: Shelf-acetabuloplasty offers symptomatic relief to adults with acetabular dysplasia but overall deteriorates with time. About 50% of the patients do not need THR for over 10 years. Best results with shelf-acetabuloplasty were achieved in patients with slight or no joint narrowing.

Introduction: With the increasing use of CAOS techniques in Orthopaedic Surgery it is important to be aware of verification studies and sources of error that can occur. Computer assisted navigation systems should be tested with a known true standard such as a phantom model and then verified with cadaver studies before clinical trials are instituted. Errors can occur.

Materials and Methods: A major focus for hip arthroplasty navigation has been on acetabular cup anteversion and inclination. Non CT navigation systems rely on an anterior pelvic plane, which is selected by the surgeon. This study looked at repeated measurements of a surgeon’s ability to manually pick the pubic symphysis and the ASIS and compared this to the same points selected fluoroscopically. A navigated acetabular cup was performed aiming for abduction of 45° and anteversion of 20°. The software model was then manipulated to transpose the different registrations to see what compound effect the anterior pelvic plane error would have.

Results: Significant intra and inter observation error was recorded for registration by palpation compared to points registered by the fluoroscopic method. An error of up to 9.6° cup inclination and 11.2 ° cup anteversion could be introduced with a palpation method.

Conclusion: This cadaver study indicates that with hip arthroplasty, registration from a fluoroscopic image was more accurate with a respect to determining the anterior pelvic plane when compared to direct palpation. Like all surgery done with computer navigation, registration requires an accurate determination of the points that the software needs for calculation. This must always be borne in mind when evaluating methods for CAOS.

Introduction: Computer assisted Orthopaedic surgery (CAOS) has a lot to offer in orthopaedic trauma surgery. Based on real time fluoroscopic images CAOS can optimise the treatment of bone fractures while importantly reducing radiation exposure to both surgeon and patient. We describe our early experience with the use of the Brain LAB Vector Vision trauma software for the treatment of femoral shaft fractures with intramedullary nailing and distal cross bolting.

Materials and Method: At the beginning of the procedure two minimally invasive reference arrays are attached to the proximal and distal femur. Seven fluoroscopic images are acquired and automatically transferred to the navigation unit. These images are used to identify the shaft axis of both fragments, the neck axis and the posterior condylar axis to control alignment and rotation. Segmentation of the distal fragment is also performed to facilitate real time movement of the fragments during reduction. Two more fluoroscopic images are acquired once the nail is inserted to plan and navigate the interlocking screws. The software displays a real-time position of the drill guide during screw navigation. AO titanium femoral nails were used in all cases.

Results: Like all new introductions of CAOS technology there are problems to solve and tips that improve the technique. Specifically, proximal pin fixation needs to be rigid and is best put in to the greater trochanter to prevent obstruction of the nail. Real time fracture reduction has been easily achieved. Distal cross bolting requires at the present stage a further two fluoroscopic images when the nail is inserted. Navigation of the drill bit is accurate, but care needs to be taken because of the potential motion of the tip of the drill bit. As the software is generic any manufacturer’s nail can be inserted. There may be some advantage, however, in viewing a virtual nail insertion based on stored data in the software.

Conclusion: Acquiring good images and positioning of the navigation unit are key factors in successfully treating a femoral nail with the aid of CAOS. Already significant time savings in radiation exposure have been achieved in the early cases and this is expected to improve with more experience.

Background: Hip dysplasia is a complex developmental process. Untreated acetabular dysplasia is the most common cause of secondary hip osteoarthiritis. With increased interest in redirectional pelvic osteotomies, the role of the shelf procedure needs to be re-defined.

Aim of the study: to investigate the effectiveness of the shelf procedure in adults with symptomatic acetabular dysplasia by assessing the functional and radiological outcome at a minimum of five years follow-up.

Material and Methods: Seventy-six consecutive adults with symptomatic acetabular dysplasia treated with acetabular shelf augmentation, have been followed up for an average period of 11 years (range: 6–14). The mean age was thirty-three years (range: 17–60 years). The Oxford hip score (OHS) was used for clinical assessment. Centre-edge angle (CEA) and acetabular angle (AA) were measured to determine femoral head coverage. Osteoarthiritis severity was based primarily on the width of the joint space using the De Mourgues classification. Survivorship analyses using conversion to THR as an endpoint were performed. logrank test was used to compare the outcome of the shelf against the variables of age, preoperative osteoarthiritis, preoperative and postoperative AA, CEA angles.

Results: The shelf procedure improved the mean preoperative CEA from 11° (range: 20° to 17°) to 50° postoperatively (range: 30° to 70°) and the mean preoperative AA from 52° (range: 46° to 64°) to 32° postoperatively (range: 18° to 57°). The Mean OHS was 34.6 (hip score maximum: 48). Thirty percent of hips needed THR at an average duration of 7.3 years. Survival analysis using conversion to THR as an endpoint was 86% (CI, 76%–95%) at five years and 46% (CI, 27%–65%) at ten years. The survival in the 44 patients with only slight or no joint space narrowing was 97% (CI, 93%–100%) at 5 years and 75% (CI, 51%–100%) at 10 years. This was significantly higher (p= 0.0007) than the survival in the 32 patients with moderate or severe osteoarthiritis, which was 76% (CI, 55%–89%) at 5 years and 22% (CI, 5%–38%) at 10 years. There was no significant relationship between survival and age (p= 0.37), pre and postoperative centre-edge angle (p= 0.39), or acetabular angle (p= 0.85).

Conclusion: Shelf acetabuloplasty is a reliable, safe procedure offering medium-term symptomatic relief for adults with acetabular dysplasia. The best results were achieved in patients with slight or no joint space narrowing.

Introduction and Aims: The standard treatment for an infected total hip replacement involves removal of all foreign material and re-implantation in either one or two stages with antibiotic cement. This study has investigated the use of cementless reconstruction in infected hip arthroplasties to determine if there is a difference in the re-infection rate.

Method: Thirteen patients (three females and 10 males) with an average age of 67 have been followed-up prospectively after revision hip surgery for infection. Removal of the prosthesis was followed by six weeks intravenous antibiotics and in some cases a period of oral therapy. Reconstruction was undertaken at a median of four months post Girdlestone’s arthroplasty, with the exception of a one-stage exchange for medical reasons. Cementless titanium femoral components were used in all revisions and titanium acetabular components where applicable. Allograft and cage reconstruction were employed for major pelvic defects.

Results: Patients have been followed-up for an average of 58 months (range 12–96 months), with no loss to follow-up. Bacteria were cultured from eleven (11) of the thirteen (13) patients and the other two were clinically septic. Bacteria cultured included MRSA, Staph. Aureus, E.Coli and Strep. Faecalis. All prostheses remain in situ with improvement in both Charnley and Oxford hip scores. No recurrence of infection has been documented clinically or radiologically and no component is loose.

Conclusion: Debate still exists about the merits of one vs. two-stage reconstruction for infected hip arthroplasty. This series with mid-term follow-up demonstrates that cementless reconstruction for infected hip arthroplasty is successful in providing an infection-free stable revision.

We followed up 76 consecutive hips with symptomatic acetabular dysplasia treated by acetabular shelf augmentation for a mean period of 11 years. Survival analysis using conversion to hip replacement as an end-point was 86% at five years and 46% at ten years. Forty-four hips with slight or no narrowing of the joint space pre-operatively had a survival of 97% at five and 75% at ten years. This was significantly higher (p = 0.0007) than that of the 32 hips with moderate or severe narrowing of the joint-space, which was 76% at five and 22% at ten years. There was no significant relationship between survival and age (p = 0.37) or the pre- and post-operative centre-edge (p = 0.39) and acetabular angles (p = 0.85).

Shelf acetabuloplasty is a reliable, safe procedure offering medium-term symptomatic relief for adults with acetabular dysplasia. The best results were achieved in patients with mild and moderate dysplasia of the hip with little arthritis.

Aim: To investigate the functional and radiological outcome of shelf acetabuloplasty in adults with significantly symptomatic acetabular dysplasia, with a minimum of a 5 year follow-up.

Material and Methods: 77 consecutive shelf procedures (68 patients) with an average follow-up of 10.9 years (range: 6–17) were reviewed. The Oxford hip score (OHS) was used for clinical assessment. Centre-edge angle (CEA) and acetabular angle (AA) were measured as indicators of joint containment. The severity of osteoarthiritis was based primarily on the extent of joint space narrowing. Survivorship analyses using conversion to THR as an endpoint were performed. Logrank tests were used to compare the survivorship of the shelf procedure against the variables of age, preoperative osteoarthiritis, pre and postoperative AA, CEA angles.

Results: The average age at time of surgery was 33 years (range: 17–60). At the time of the last follow-up, the mean OHS was 34.6 (maximum score: 48). Mean postoperative CEA was 55 (Pre-operatively: 13 degrees) while mean postoperative AA was 31 (Pre-operatively: 48 degrees). Thirty percent of hips needed THR at an average duration of 7.3 years. The survival in the 45 patients with only slight or no joint space narrowing was 97% (CI, 93%-100%) at 5 years and 75% (CI, 51%-100%) at 10 years. This was significantly higher (p≤= 0.0007) than the survival in the 32 patients with moderate or severe osteoarthiritis, which was 76% (CI, 55%-89%) at 5 years and 22% (CI, 5%-38%) at 10 years. There was no significant relationship between survival and age, pre and postoperative AA, CEA angles (p> 0.05).

Conclusion: Shelf-acetabuloplasty offers symptomatic relief to adults with acetabular dysplasia but overall deteriorates with time. About 50% of the patients do not need THR for over 10 years. Best results with shelf-acetabuloplasty were achieved in patients with slight or no joint narrowing.

Introduction Vitamin D deficiency has been reported widely in various community groups but especially in the osteoporotic/fracture population. We decided to investigate the incidence in an elective female population undergoing hip or knee arthroplasty as this has not been previously reported.

Methods Data was collected prospectively from a group of female patients who were undergoing hip or knee arthroplasty for osteoarthritis. Patients with rheumatoid or inflammatory arthritis were excluded, as were patients on Vitamin D supplements. Serum 25-hydroxyvitamin D (25 OHD) levels were measured as part of routine pre-operative work-up. A total of 40 female patients over a 12 month period were checked, with average age 66 years (range 15 to 93 years). Average height was 151 cm and weight 67 kg. Thirty total hips and 10 total knee replacements were performed. Vitamin D deficiency was classified as either marginal (25 OHD levels ranging from 25 to 50 nmol/L or frank (25 OHD levels, < 20–25 nmol/L).

Results Eleven patients out of 40 (27.5%) had marginal deficiency and four of those patients (10%) had frank vitamin D deficiency. There was no correlation with height or weight or age.

Conclusions This small study suggests that a significant percentage of patients undergoing elective lower limb arthroplasty for osteoarthritis have low Vitamin D levels.

Introduction The accuracy of UCA implantation is an important prognostic factor in survivorship. Previously, conventional instrumentation was adapted for UCA, possibly contributing to a lower long-term survivorship. This study aims to assess UCA position on x-rays, performed through a minimally invasive approach, in comparison to UCAs utilising an open approach.

Methods Patients were selected for UCA according to strict criteria. In particular, a varus knee < 15 and correct-able,< 15 fixed flexion deformity, intact cruciate ligaments and weight bearing knee x-rays indicating osteoarthritis in the antero-medial region and relative lateral compartment sparing. Patello-femoral joint disease was not an exclusion criterion. Ultimately, the decision to proceed with UCA was made at the time of surgery where the cruciates and lateral compartment could be inspected directly. Data was retrieved retrospectively for a continuous cohort of patients. Radiographs of component alignment were measured by an independent observer not involved in the surgery. Radiographs were measured for 56 UCAs, performed by one of the authors. Twelve patients had bilateral UCAs at the same surgery and one patient had a combined UCA/TKR. Short knee x-rays (anterior-posterior and lateral views) were used to estimate the axes of the femur and tibia as the reference points for component measurements.

Results The femoral component varus/valgus angle was 5.6° (range: 2 to 10) and flexion/extension angle was 4.9° (range: 0 to 11). The tibial component varus/valgus angle was 86.4° (range: 80 to 89°) and the postero-inferior tilt angle was 83° (range: 80 to 85). There was no radiolucency at the tibial plateau interface greater than one millimetre. One patient was treated for deep vain thrombosis and two patients underwent manipulations due to reduced range of motion. There were no deep or superficial infections and no UCA revisions.

Conclusions Radiological analysis of Oxford UCAs using a minimally invasive technique demonstrates similar implant positioning compared to the open approach. Patients gain the advantage of earlier recovery due to less synovial and quadriceps disturbance and no patella dislocation. Ongoing follow-up is required to determine whether these benefits extend to improved prosthesis survivorship.

Introduction THR is a successful procedure with excellent long term results. With many patients requiring the procedure there is some advantage in rapid recovery and early discharge. This may require a change in the surgical approach and peri-operative management. We report the first series of a new minimally invasive surgical approach for THR.

Methods A two incision approach for THR has been developed after extensive cadaver tests. This consists of an anterior muscle splitting incision to insert the cup and a posterior incision for the stem insertion. The authors have undergone cadaver training and clinical surgery before embarking on clinical trials. Patients included in this study are those people awaiting THR who were selected for a cementless prothesis and who would benefit from early rehabilitation. Patients with previous surgery, hip dysplasia and significant obesity were excluded. An initial study group are presented with an average age of 59, average height 168 cms and average weight 71 kg.

Results Average length of stay was 3.7 days with an average operative time of 90 minutes. Average blood loss 505 mls with an average blood usage of 1.1 units. Early complications include lateral cutaneous nerve of thigh palsy (50% resolution at three months), two stable trochanter fractures, one infection and one anterior dislocation at eight weeks with a ceramic implant.

Conclusions The approach is technically difficult and initially time consuming. It does enable quicker mobilisation and appears to result in less need for analgesia post-operatively. We believe it is important to present the early results so the technique can be discussed and potential problems avoided. A randomised, prospective trial with clinical and RSA follow-up is underway.

Introduction: Persistent acetabular dysplasia is a recognized cause of premature hip arthritis. Treatment options include joint preservation (acetabuloplasty/osteotomy) or salvage procedures (THR). Presence of a deficient acetabulum and an elevated acetabular centre make THR technically demanding with uncertain outcome. Shelf ace-tabuloplasty is a viable option, however, most reports in the literature focus on results in children and adolescents.

Aim: To investigate the functional and radiological outcome of shelf acetabuloplasty in adults with significantly symptomatic acetabular dysplasia.

Material and Methods: 77 consecutive shelf procedures (68 patients) with an average follow-up of 10.9 years (range: 6–17) were reviewed. The Oxford hip score (OHS) was used for clinical assessment. Centre-edge angle (CEA) and acetabular angle (AA) were measured as indicators of joint containment.

Results: The average age at surgery was 33 years (range: 17–60). At the time of last follow-up; the mean OHS was 34 (maximum score: 48). Mean postoperative CEA was 59 (Pre-operatively: 16.2 degrees) while mean postoperative AA was 31 (Pre-operatively: 47.5 degrees). Thirty percent of hips needed THR at an average duration of 7.3 years. Pre-operative arthritis was present in 32 hips out of which 17 (53 percent) needed THR. Out of the remaining 45 hips, only 6 (13 percent) needed THR. No correlation was found between the acetabular indices and the outcome.

Conclusion: Shelf-acetabuloplasty offers symptomatic relief to adults with acetabular dysplasia and can delay the need for THR for over 10 years. Best results with shelf-acetabuloplasty were achieved in patients without preoperative arthritis.

Correct alignment is important for success in total knee replacement. Currently this is achieved by a combination of intramedullary and extramedullary alignment using jigs and cutting blocks. This multicentre study evaluates the use of computer assisted planning and the interactive guidance of instruments for total knee replacement.

Prior to surgery computer scans of the hip, knee and ankle were performed of patients enrolled in the study. Pre operative planning of the position and size of the knee components was performed by the surgeon using a CT based Vector Vision Navigation System (Brain LAB AG, Heimstetten, Germany). P.F.C.x (De Puy Leeds UK) knee replacements were then implanted in 38 patients. Surgery was carried out according to the standard surgical technique using traditional instruments. Information of the planned and intraoperatively recorded position of the cutting blocks were analysed to check varus/valgus alignment, flexion/extension alignment, the amount of planned resection from both the femoral and tibial bones and the size of the components. Information from all the separate centres was sent to a central data processing base for analysis.

Results were calculated comparing the differences between the planned and performed cuts for each of the different variables studied. Graphs demonstrate the differences in the alignment between that planned by the surgical navigation system and what was actually carried out by the instrumented cuts.

Based on the data obtained from the multicentre study we have concluded that the planned position of the implants using the standard instruments was similar to that using the Vector Vision Navigation System. We believe that it is safe to proceed with surgical navigation total knee arthroplasty using the P.F.C.x total knee prosthesis with Image Guided Surgery and a further multicentre study is currently underway evaluating this.

Before proceeding to longer-term studies, we have studied the early clinical results of a new mobile-bearing total knee prosthesis in comparison with an established fixed-bearing device. Patients requiring bilateral knee replacement consented to have their operations under one anaesthetic using one of each prosthesis. They also agreed to accept the random choice of knee (right or left) and to remain ignorant as to which side had which implant. Outcomes were measured using the American Knee Society Score (AKSS), the Oxford Knee Score (OKS), and determination of the range of movement and pain scores before and at one year after operation.

Preoperatively, there was no systematic difference between the right and left knees. One patient died in the perioperative period and one mobile-bearing prosthesis required early revision for dislocation of the meniscal component.

At one year the mean AKSS, OKS and pain scores for the new device were slightly better (p < 0.025) than those for the fixed-bearing device. There was no difference in the range of movement.

We believe that this is the first controlled, blinded trial to compare early function of a new knee prosthesis with that of a standard implant. It demonstrates a small but significant clinical advantage for the mobile-bearing design.

Introduction: There has been significant development in computer technology in recent years and this has led to applications in orthopaedic surgery. Of particular interest is computer assisted joint arthroplasty to enable accurate insertion of the components based on CT generated images of the patient’s bones.

Methods: Twenty-five patients have undergone computer assisted total knee arthroplasty using a computer guidance system (Vector Vision, Brain Lab, Munich) implanting a PFC cruciate retaining total knee replacement (TKR) (Depuy, Leeds). Pre-operative CT scans were obtained from each patient and alignment and sizing were calculated before surgery. Intra-operatively, an infrared camera tracked the instruments and the patient’s limb was accurately mapped in space by surface matching the bone and comparing it with the CT scan. For the purpose of the study the computer generated alignments and sizing were evaluated along with the use of traditional instruments and stored in a database.

Results: These have been evaluated comparing computer assisted and instrumented knee arthroplasty. Variables measured include the AP femoral cuts, rotational femoral alignment, and tibial axis alignment in AP and lateral planes.

Conclusions: Computer assisted orthopaedic surgery has undergone a rapid development in the last 18 months to enable real-time intra-operative images to be viewed in a moving limb with a degree of accuracy previously not possible. The use of this technology may lead to more accurate alignment of hip and knee prostheses and therefor help to reduce wear in the long-term.

Introduction: Patient education and informed consent are areas of clinical practice that are taking an ever-increasing proportion of a surgeon’s time and effort. The expectation is that this trend will continue, as medical malpractice litigation becomes more commonplace. Patients are also requiring increased access to medical information to help facilitate decisions about their healthcare. With the increasing use of computers and improvements in technology modules to aid patients’ understanding have become available and may prove useful in patient education.

Method: A computer-based multimedia module of total hip replacement (THR) has been developed. These involve three-dimensional (3D), animated computer graphics with text and spoken word. A questionnaire based on educational models was designed to test ease of use and patients’ comprehension after viewing the module.

Results: A pilot study involved 20 patients each awaiting elective surgery for THR. The results showed a good comprehension and understanding of the nature of the surgery and the possible complications.

Conclusions: We have shown that a 3D-multimedia patient education module improved patients’ understanding of THR surgery and its possible complications. The use of 3D multimedia modules has the potential to save the surgeon time whilst ensuring that his/her patients have given informed consent to their forthcoming surgery. It is hoped that better-informed consent may equate to a reduction in medical malpractice activity and thus insurance premiums.

Aim: Failed primary hip arthroplasty often results in significant loss of host bone. Revision surgery may require bone grafting to restore bone stock prior to insertion of a new cup. A two to five year follow up of one method of acetabular revision for severe bone stock loss is presented

Materials and Methods: Seventeen patients had acetabular revision with the use of impacted morcellised bone and a cage reconstruction with a cemented cup. The average age at the time of revision was 62. All patients were followed prospectively with regular X-rays. A variety of cages were employed and bone graft was hand morcellised from femoral heads or cadaver distal femurs.

Introduction: Infected hip arthroplasties have usually been managed with either one or two stage revisions using antibiotic impregnated cement to fix the components. The use of cementless fixation has been less widely reported. The results on the femoral side have been less encouraging.

Aim: To present the short to medium term results of cementless revision for infected hip arthroplasty.

Methods: Ten patients who had undergone cementless revisions for infected hip arthroplasties have been followed prospectively. There were eight males and two females with an average age of 67 years. Nine of the 10 patients were treated with two-stage revisions with one female undergoing a one-stage revision for medical reasons. The diagnosis of sepsis was made on the basis of bacterial cultures and positive histology from all patients. Removal of the prosthesis was followed by the administration of intravenous antibiotics for six weeks and, in some, cases oral antibiotics for several months. The reconstructions were undertaken following the Girdlestone’s arthroplasties with a range from eight weeks to three years, (with the exception of the one stage exchange).

Results: The patients were examined from 18 to 64 months after the surgery with none lost to follow-up. All prostheses remained in situ with improvements in the Charnley and Oxford hip scores. There had been no recurrence of infection and no clinical or radiological evidence of loosening.

Discussion: Debate still exists about the merits of one-stage versus two-stage reconstruction for an infected hip arthroplasty. The use of antibiotic-impregnated cement has been recommended, especially for the femoral component. This series demonstrated that cementless reconstruction for infected hip arthroplasty was successful in providing an infection free, stable hip in the short to medium term.

Purpose: As part of the step-wise introduction of a meniscal-bearing total knee replacement (Oxford TMK) we needed to know, before proceeding to longer term studies, whether its early clinical results were at least as good as those of an established fixed bearing device (AGC).

Material and Methods: With ethical approval, patients requiring bilateral knee replacement for osteoarthritis consented to have the operations under one anaesthetic using one of each prosthesis; to accept random choice of knee; and to remain ignorant which side was which. American Knee Society Scores, Oxford Knee Scores, ROM and pain scores were to be recorded preoperatively and at one year. By January 2001, 40 patients had reached one year and data is available for 36.

Results: Preoperatively there was no difference between the two knees. One patient died in the peri-operative period.

Results at one year (TMK first): AKSS(Knee) 91.6 / 84.1 (p=0.003), OKS 39.8 / 37.6 (p=0.006), ROM 104 / 104 (p=0.364), Pain (AKSS) 47.3 / 41.7 (p=0.01), Pain (OKS) 3.5 / 2.9 (p=0.006).

Conclusion: The TMK performed as well as the AGC. Its AKSS, OKS and pain scores were significantly better. We believe this controlled, blinded trial is the first to have compared the function of a new knee prosthesis with a standard implant before marketing; and the first to have demonstrated a significant clinical advantage for a meniscal-bearing over a fixed bearing TKR. The comparison of bilateral implants in the same patient can reveal significant differences while putting at risk many fewer subjects than would be needed for a classical twocohort RCT.

We assessed the efficacy of intraoperative frozen-section histology in detecting infection in failed arthroplasties in 106 hips and knees. We found inflammatory changes consistent with infection (an average of one or more neutrophil polymorphs or plasma cells per high-power field in several samples) in 18 cases; there was a significant growth on bacterial culture in 20 cases. Compared with the bacterial cultures, the frozen sections provided two false-negative results and three false-positive results (sensitivity, 90%; specificity, 96%; and accuracy, 95%). The positive predictive value was 88%, the negative value, 98%. These results support the inclusion of intra-operative frozen-section histology in any protocol for revision arthroplasty for loose components.