Introduction

Depression is a common co-morbidity in Total Hip Arthroplasty (THA). Chronic pain and depression influence one another. Postoperative outcomes and satisfaction rates are affected by depression.

Background

The prevalence of immunocompromised patients undergoing Total Hip Arthroplasty (THA) is increasing worldwide as a consequence of advances in treatment. HIV is presenting in an older population group and concerns of higher rates of infection, early failures and dangers posed to healthcare workers exist. This study is imperative to predict future burden of THA and make subsequent provisions

Background:

Antibiotic prophylaxis prior to dental and other procedures when patients have joint replacements in situ remains controversial. Recommendations seem to generally be intuitive and not based on any sound scientific evidence. Recently, the American Academy of Orthopaedic Surgeons altered their previous standpoint and suggested that orthopaedic surgeons review their current practice of routine prescription of antibiotic prophylaxis.

Introduction:

Total Hip Replacement (THR) is a proven and effective surgical procedure. One of the main limiting factors of the longevity of THR is the performance of the bearing surface. The optimum bearing surface choice, however, remains controversial. We wanted to understand what influenced the choice of bearing surfaces amongst South African orthopaedic surgeons. We also wanted to know if there was any consensus between surgeons and the orthopaedic trade.

Background:

Massive acetabular defects remain an unresolved challenge in revision arthroplasty surgery of the hip. We report on 7 patients treated with custom made acetabular components to manage these massive boney defects.

We report on a series of long-stemmed femoral components used in revision total hip replacements which fractured, and were subsequently revised.

Introduction

Antibiotic loaded polymethyle methacrylate spacers are commonly used in the management of septic hip replacements.

Metal ion levels are used to track the performance of metal containing bearings in hip replacement patients. Changes in whole blood metal ion levels are indicators of wear rates in these bearings. Normal metal ion levels are variable, and range widely. Changes in these “non-bearing” levels over a period of time may influence the monitoring of these bearings.

The advantages of computer navigated total knee replacement are well documented in the literature, however, increased surgical time and cost issues remain the major deterrent for the wide use of this technology. Placement of cutting jigs under computer guidance forms a major aspect of computer assisted knee replacement surgery. The use of a motorized mini-robotic cutting jig allows for a more precise and time efficient execution of the femoral cuts under computer guidance. We present a preliminary report on our experience using standard computer assisted surgery (CAS) jigs and mini robotic motorized jigs in computer navigated knee replacement

Purpose of Study:

To look at the difference in metal ion levels using Ceramic on Metal (COM) and Metal on Metal (MOM) bearings in Total Hip Replacements, comparing the results between well placed and poorly placed cups.

Monitoring the performance of hip replacements post-operatively is tedious and costly, necessitating radiological examinations as well as other specialized examinations such as whole blood metal ion levels. In an effort to control escalating costs, we conducted an ethically approved clinical trial to assess the efficacy of basic acoustic monitoring equipment to asses these implants.

The search for the ideal bearing surface in Total Hip Replacements continues. The current ‘best’ materials are felt to be combinations of metal, ceramics and cross-linked polyethylene. Laboratory studies suggest that ceramic-on-metal articulations may provide distinct advantages. This study aims to identify the best bearing surface combination with the lowest adverse side effect profile.

Between February 2004 and September 2007, 164 hips were replaced in 142 patients. 39% were male and 69% were female. The average age at surgery was 53 years (17-72 years). Follow-up assessment included radiographs, the Harris Hip Score and whole blood samples for metal ion levels. Complications to date included 3 hips which needed femoral revision because of surgery related factors, and 3 cases of sepsis of which 1 settled and 2 needed revision. One hip needed revision of head and liner to a larger bearing size for recurrent dislocations, and is no longer being followed up for blood metal ions.

Post-operative whole blood metal ion levels were compared to pre-operative levels to determine the increase or decrease in metal ion levels. There were no changes in those patients with ceramic-on-ceramic and ceramic-on-polyethylene articulations. Moderately raised whole blood metal ion levels were noted at 3 months in the ceramic-on-metal group, while the metal-on-metal group show the greatest increase.

This study agrees with laboratory bearing surface wear studies demonstrating lower wear rates in the ceramic-on-metal group compared to the metal-on-metal group. With concerns related to high blood metal ion levels in metal-on-metal articulations, ceramic-on-metal bearing surfaces may well become a bearing surface of choice in the future, but progress needs to be monitored in the longer term.

The combination of a ceramic head articulating against a metal acetabular liner (CoM) has shown reduced metal ion levels compared with a metal-on-metal bearing (MoM) in hip simulator studies. A randomized prospective clinical trial was undertaken using CoM and MoM bearings in an otherwise identical total hip procedure. The initial clinical results were encouraging. This report comprises a further review of metal ion data.

Patients received identical components with the exception of the bearing surface material but all were 28mm diameter. All components were supplied by DePuy International Ltd. Patients were assessed pre-operatively, 3m, 12m and > 24m (median 32m). Whole blood samples were collected at regular follow-ups, frozen and analysed in batches using high resolution Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). All recruited patients are included irrespective of outcome. However some patients failed to attend specific follow-ups and some contaminated samples had to be discarded. Statistical significance was analyzed using a non-parametric comparison (Mann-Whitney test). After 3m and 12m implantation there were between 21 and 24 patients available for analysis in both the CoM and MoM cohort and after > 24m point 10 and 9 respectively.

There were four outliers (either Cr or Co > 10ug/l) in both the CoM and MoM groups. In common with previous studies (with the exception of two marginal outliers), these were related to component position. They were implanted with either a cup abduction angle of > 55°, an anteversion angle of > 30° or both. Other studies with the same design of component have reported no significant outliers.

The median Cr and the Co levels are lower with the CoM bearing compared with the MoM at all measurements points following implantation. The median background (pre-operative) levels for the combined CoM and MoM group were Cr: 0.22ug/l and Co: 0.49ug/l. These were significantly different (p=0.006).

In the CoM group, the median 12m Cr and Co values were 0.43ug/l and 0.72ug/l respectively. The comparable values for MoM are 0.68ug/l and 0.83ug/l. Increases in metal ion levels from pre-operative levels are used as the primary ion level outcome in this study because the background level will comprise of the order of 30–50% of the overall value. The increase in Cr for CoM and MoM from pre-op levels to 12m significantly different for Cr (p=0.015). It has a lower significance for combined metal ion levels (p=0.029). This difference in not significant for Co (p=0.195).

In agreement with predictions from hip simulator studies, CoM bearings in this study produced lower levels of metal ions than comparable MoM bearings at all time points. However the difference is less than that predicted in the laboratory and is much more pronounced with Cr than with Co.

Purpose: Whole blood metal ion levels remain a concern in those patients undergoing total hip replacement with metal bearing surfaces. The determination of baseline reference levels are essential if useful information can be gleaned from in vivo studies of functioning implants. We set out to prospectively determine chromium and cobalt metal ion concentrations in patients undergoing total hip replacement to determine reference levels of these metal ions.

Method: 100 patients with normal renal function, no occupational or environmental exposure to cobalt and chromium, and an absence of implanted metals were recruited into the study. Metal ion levels were determined using two different assay methods. Both ICP-MS (Inductively Coupled Plasma Mass Spectroscopy) and GFAAS (Graphite Furnace Atomic Adsorption Spectroscopy) are well recognized analytical techniques for the quantification of trace elements. Levels were correlated with gender, age and place of residence.

Results: There was considerable variability in whole blood metal ion levels, with the ICP-MS being more sensitive and consistent than the GFAAS method. Direct comparison of concentration levels determined by the two methods revealed no significant correlation. There was no correlation with age, gender and place of residence.

Conclusion: Our findings would favour the use of the ICP-MS to determine reference levels and as a baseline for metal ion surveillance pre-operatively in patients undergoing metal-on-metal total hip replacements. We also determined that changes in whole blood metal ion levels are more significant than actual levels in patients who have undergone total hip replacement.

Recurrent patellar dislocation is a relatively common disorder in young patients. Historically, treatment options have been based on the underlying disorder predisposing the patient to the dislocation. This has resulted in various soft tissue reefing procedures, patella tendon realignment procedures and boney realignment procedures.

Further research has shown that the medial patello-femoral ligament (MPFL) is the primary restraint to lateral patella subluxation and dislocation. Many authors have published their successful treatment of recurrent patella dislocation by reconstruction of the medial patellofemoral ligament. The most widely used is autologous semitendinosis tendon grafts, as well as synthetic materials, and MPFL reconstructions may be combined with boney procedures. Varieties of fixation techniques have been described involving both the patella and femoral sides.

We present a technique of MPFL reconstruction using the autologous ipsilateral quadriceps tendon. Our technique avoids the morbidity associated with semitendinosis graft harvesting and the drill holes in, and potential resulting fracture of, the patella. The technique is also simple and is associated with decreased procedure costs.

We present the technique and a series of six patients (seven knees) with follow up ranging from eight months to nine years. The average age of patients at the time of surgery 16 to 28 years (mean = 20 years). There have been no redislocations. The median Kujala patellofemoral knee score at follow up was 97 out of 100 (Range 69–100). The results compare very favorably to published results using other techniques.

Our technique of reconstructing the MPFL is reliable, produces good results using an objective knee score, and is cost effective.

Seventy staff members participated from a potential pool of approximately one hundred staff on duty at the time. Of the seventy staff who participated in this research project a total of three staff members were within 50 mls of the correct amount for each of the three samples. Overall staff were very poor at estimating blood loss.

Staff working in the operating theatre, no matter what their affiliation or years of experience, are not accurate when estimating blood loss spilt into a patients bed. A tool that aids in blood loss estimation is a valuable addition to the theatre resource manual.

Dislocations remain a significant problem, especially after revision hip surgery. Revision of components, particularly in elderly patients with co-morbidities, can be fraught with complications. The surgeon’s options are sometimes restricted, particularly when the acetabular and femoral components are well fixed. Increased head lengths are often utilised to increase tissue tension, and thus improve stability.

As a niche solution we have designed a low cost modular femoral neck extender. They are manufactured from medical grade Cobalt-Chrome, conforming to ISO 200, CE mark and EN46001 standards. Available in three incremental lengths and with different connecting Morse tapers, increases in effective neck lengths of up to 49 mms can be achieved. When both the original acetabular and femoral components are well orientated, the resultant increased tissue tension imparts stability to the hip.

We present a series of five patients where we have used a femoral neck extender to achieve stability of a total hip replacement. Four patients had had multiple previous dislocations. One patient was unstable at the time of revision surgery because of a high hip centre. The average age of the patients was 72 years, and the number of previous dislocations averaged four. The average follow-up after surgery was 22 months. No patients have redislocated their hips.

We present our novel femoral neck extenders as an elegant and cost effective solution to convert an unstable hip to a stable hip, especially when the patient has well fixed and orientated components not in themselves requiring revision.

A randomised prospective study of four bearing surfaces in hip replacements is being conducted. The primary objective is to identify the best long term bearing surf ace clinically and radiographically, and metal ion levels have been measured in all cases.

Patients have been randomised to the four bearing surfaces viz. Ceramic-on-XLinked Polyethelene, Ceramic-on-Ceramic, Metal-on-Metal and Ceramic-on-Metal. Pre-operative blood samples and follow-up blood samples for metal ion analysis using ICP-MS method have been taken in all patients. As at February 2008 187 patients have been recruited, and metal ion levels at one year are available in 52 patients.

Metal ion levels are not increased with Ceramic-on-XLPE or Ceramic-on-Ceramic bearings. At one year follow-up the metal ion levels in Ceramic-on–Metal bearings is half that of Metal-on-Metal bearings using mean levels, and one third using median levels. Of note is that chromium levels in Ceramic-on-Metal bearings is the least elevated.

Due to the laboratory evidence that ceramic-on-metal bearings have the best surf ace wear characteristics with no head stripe wear on a ceramic head, and the laboratory and clinic al evidence of lower metal ion levels, Ceramic-on-Metal hip replacements could be one of the bearing surfaces of the future.

Dislocations remain a significant problem, especially after revision hip surgery. Revision of components, particularly in elderly patients with co-morbidities, can be fraught with complications. The surgeon’s options are sometimes restricted, particularly when the acetabular and femoral components are well fixed. Increased head lengths are often utilized to increase tissue tension, and thus improve stability.

As a niche solution we have designed a low cost modular femoral neck extender. They are manufactured from medical grade Cobalt-Chrome, conforming to ISO 200, CE mark and EN46001 standards. Available in 3 incremental lengths and with different connecting Morse tapers, increases in effective neck lengths of up to 49 mm can be achieved. When both the original acetabular and femoral components are well orientated, the resultant increased tissue tension imparts stability to the hip.

We present a series of 5 patients where we have used a femoral neck extender to achieve stability of a total hip replacement. 4 patients had had multiple previous dislocations. 1 patient was unstable at the time of revision surgery because of a high hip centre. The average age of the patients was 72 years, and the number of previous dislocations averaged 4. The average follow-up after surgery was 22 months. No patients have redislocated their hips.

We present our novel femoral neck extenders as an elegant and cost effective solution to convert an unstable hip to a stable hip, especially when the patient has well fixed and orientated components not in themselves requiring revision.

Recurrent patellar dislocation is a relatively common disorder in young patients. Historically, treatment options have been based on the underlying disorder predisposing the patient to the dislocation. This has resulted in various soft tissue reefing procedures, patella tendon realignment procedures and boney realignment procedures.

Further research has shown that the medial patellofemoral ligament (MPFL) is the primary restraint to lateral patella subluxation and dislocation. Many authors have published their successful treatment of recurrent patella dislocation by reconstruction of the medial patellofemoral ligament. The most widely used is autologous semitendinosis tendon grafts, as well as synthetic materials, and MPFL reconstructions may be combined with boney procedures. Varieties of fixation techniques have been described involving both the patella and femoral sides.

We present a technique of MPFL reconstruction using the autologous ipsilateral quadriceps tendon. Our technique avoids the morbidity associated with semitendinosis graft harvesting and the drill holes in, and potential resulting fracture of, the patella. The technique is also simple and is associated with decreased procedure costs.

We present the technique and a series of 6 patients (7 knees) with follow up ranging from 8 months to 9 years. The average age of patients at the time of surgery 16–28 years (mean = 20years). There have been no redis-locations. The median Kujala patellofemoral knee score at follow up was 97 out of 100 (Range 69–100). The results compare very favourably to published results using other techniques.

Our technique of reconstructing the MPFL is reliable, produces good results using an objective knee score, and is cost effective.

Whole blood metal ion levels remain a concern in those patients undergoing total hip replacement with metal bearing surfaces. The determination of baseline reference levels are essential if useful information can be gleaned from in vivo studies of functioning implants. We set out to prospectively determine chromium and cobalt metal ion concentrations in patients undergoing total hip replacement to determine reference levels of these metal ions.

100 patients with normal renal function, no occupational or environmental exposure to cobalt and chromium, and an absence of implanted metals were recruited into the study. Metal ion levels were determined using two different assay methods. Both ICP-MS (Inductively Coupled Plasma Mass Spectroscopy) and GFAAS (Graphite Furnace Atomic Adsorption Spectroscopy) are well recognised analytical techniques for the quantification of trace elements. Levels were correlated with gender, age and place of residence.

There was considerable variability in whole blood metal ion levels, with the ICP-MS being more sensitive and consistent than the GFAAS method. Direct comparison of concentration levels determined by the two methods revealed no significant correlation. There was no correlation with age, gender and place of residence.

Our findings would favour the use of the ICP-MS to determine reference levels and as a baseline for metalion surveillance pre-operatively in patients undergoing metal-on-metal total hip replacements. We also determined that changes in whole blood metal ion levels are more significant than actual levels in patients who have undergone total hip replacement.

This study reports on ceramic-on-metal (CoM) bearings in total hip replacement. Whole blood metal ion levels were measured. The median increase in chromium and cobalt at 12 months was 0.08 μg/1 and 0.22 μg/1, respectively, in CoM bearings. Comparable values for metal-on-metal (MoM) were 0.48 μg/1 and 0.32 μg/1. The chromium levels were significantly lower in CoM than in MoM bearings (p = 0.02). The cobalt levels were lower, but the difference was not significant. Examination of two explanted ceramic heads revealed areas of thin metal transfer. CoM bearings (one explanted head and acetabular component, one explanted head and new acetabular component, and three new heads and acetabular components) were tested in a hip joint simulator. The explanted head and acetabular component had higher bedding-in. However, after one million cycles all the wear rates were the same and an order of magnitude less than that reported for MoM bearings. There were four outliers in each clinical group, primarily related to component malposition.

The search for the ideal bearing surfaces to be used in Total Hip Replacement continues. The current “best” materials are felt to be various combinations of metal, ceramics and cross-linked polyethylene. Laboratory studies suggest that ceramic-on-metal articulations may provide distinct advantages. This study aims to identify the best combination with the lowest side effect profile.

In February 2004 a prospective randomised trial on different bearing surfaces was started. The combinations selected were ceramic-on-cross-linked polyethylene, ceramic-on-ceramic, metal-on-metal and ceramic-on-metal. Institutional ethics clearance was obtained. In all patients uncemented femoral stems are used, with an uncemented porocoated acetabular shell. A uniform 28mm femoral head size was selected. Blood samples have been taken to measure the metal ion concentrations in all patients. These are measured pre operatively, and repeated at follow up visits at 3 months and 1 year, with further follow up at 3,5 and 10 years post operatively. Whole blood ion levels are measured using a graphite furnace atomic absorption spectrometer.

Between February 2004 and April 2006 one hundred and ten hips have undergone total hip replacement. There are 105 patients (5 bilateral). 40% are males and 60% female. The average age at operation is 52 years (17 to 72). 49% hips are left and 51% right. Follow up includes blood samples and the Harris Hip Score. Complications to date have been surgeon related, with three femoral components needing early revision for technical reasons. This has not affected the bearing surfaces. Radiological and clinical assessment shows no difference between the different bearing surface groups.

Post operative whole blood metal ion levels are compared to the patient’s pre operative level. To date there is no increase in the metal ion levels for the ceramic-on-cross linked polyethylene and ceramic-on-ceramic articulations. The ceramic-on-metal group is providing moderately raised metal ion levels, and the highest metal ion levels are in the metal-on-metal articulation group. At one year, the ceramic-on-metal group demonstrates a drop to close to pre-operative levels and these are still significantly lower than the metal-on-metal group. This confirms laboratory studies on the ceramic-on-metal articulation, which demonstrate significantly lower wear than comparable metal-on-metal articulations. The high level of metal ions in the latter groups has always been of concern.

This study demonstrates a lower blood level of metal ions in the ceramic-on-metal group. If the in vivo wear rate in this group continues to replicate the laboratory wear studies, this articulation becomes a very attractive bearing surface in younger active patients, and may well become a bearing surface of choice in the future.

The search for the ideal bearing surfaces to be used in Total Hip Replacement continues. The current “best” materials are felt to be various combinations of metal, ceramics and cross linked polyethylene. This study aims to identify the best combination with the lowest side effect profile.

In February 2004 a prospective randomised trial on different bearing surfaces was started. The combinations selected were ceramic on cross linked polyethylene, ceramic on ceramic, metal on metal and ceramic on metal. Institutional ethics clearance was obtained. In all patients uncemented femoral stems are used, and an uncemented porocoated acetabular shell. 28mm Head size was selected. Blood samples have been taken to measure the metal ion concentrations in all patients. These are measured pre operatively, and repeated at intended follow up visits at 3 months, 1, 3, 5 and 10 years post operative using a graphite furnace atomic absorption spectrometer.

Between February 2004 and 2006 seventy hips have undergone total hip replacement. There are 85 patients (11 bilateral). 40% are males and 60% female. The average age at operation is 52 years (17 to 72). 46% Hips are left and 54% right. Follow up includes blood samples and the Harris Hip Score. Complications to date have been surgeon related, with three femoral components needing early revision for technical reasons. This has not affected the bearing surfaces. Ten patients have hetero-topic ossification. Cup inclination averages at 48 degrees (32 degrees to 69 degrees). Post operative blood metal ion levels are compared to the patient’s pre-operative level. To date there is no increase in the metal ion levels for the ceramic/cross linked poly ethylene and ceramic/ceramic articulations. The ceramic metal group is providing intermediate raised metal ion levels, and the highest metal ion levels are in the metal on metal articulation group. In the laboratory the ceramic on metal articulation demonstrates the least wear of all the groups studied, with metal on metal second. The high level of metal ions in the latter groups has always been of concern.

This study demonstrates a lower blood level of metal ions in the ceramic on metal group. If the in vivo wear rate in this group is as good as the laboratory wear, it becomes a very attractive bearing surface in younger active patients.

The aim of this study was to asses the results of total hip replacements using the Elite Plus femoral stem.

During the period 1995 to 2000, 212 total hip replacements were done using the Elite Plus femoral stem. These were followed up prospectively. The cohort of patients included 11 with bilateral hip replacements. 38% of patients were male and 62% were female. The average age at surgery was 61 years, with 18% being younger that 50 years at the time of surgery. All hip replacements were done using the same surgical and cementing techniques. Both cemented and uncemented cups were used in this cohort of patients.

2 patients died peri-operatively, and 22 hips were lost to follow-up. 6 hips have been revised, with 1 revision being due to sepsis and 5 due to loosening. A further 4 hips have radiographic evidence of early loosening, and 1 other hip has developed late sepsis. None of these 5 has yet been revised. Our survivorship at an average of 9 years is 97%.

The survivorship of total hip replacements using the Elite Plus femoral stem in our unit is 97% at an average of 9 years. This compares very well with the results reported in other series. We do note though that there are 5 hips that may need revision, and this would bring the survivorship down to 94%. We feel that our good results are due to careful attention to surgical and cementing techniques, and this may explain our improved results compared to previous reports.

Good short-term results with Mt Blanc uncemented acetabular cups have been previously reported. However, in the medium term, we have observed acetabular loosening related to large granulomatous lytic lesions. To determine the cause of the polyethylene load causing the granulomatous lytic lesions, we subjected six explanted Mt Blanc acetabular cups to retrieval analysis. We also reviewed the literature on polyethylene locking mechanisms in uncemented metal-backed cups and on the deformability of metal-backed cups.

We subjected the retrieved cups to stereo-photographic analysis and to dye penetration and surface scanning electron microscopy techniques. We demonstrated severe polyethylene wear and particle generation on the back surface of the polyethylene insert. This was due both to two-body sliding wear, as characterised by surface deformation and delamination of the polyethylene, and to three-body abrasive wear, as characterised by surface roughness and embedded titanium particles. The literature confirmed that the locking mechanism of the Mt Blanc cup was particularly poor and the deformability greater than in other cups tested. This confirmed the wear patterns on the back-surface of the polyethylene liner.

We caution against the use of uncemented cups that have poor locking mechanisms for the polyethylene liners and those that deform excessively. The combination of poor locking mechanisms and titanium shells is especially dangerous.

Introduction and Aims: Aim of the study is to show whether the accuracy of alignment of a total knee pros-thesis is more dependent on the instrumentation or the skills of the surgeon.

Method: Forty patients that had total knee arthroplasties performed between September 1997 and September 1999 have been analysed. The results of prospective randomised trial using the LCS (Depuy) and IBII (Zimmer) prostheses have been analysed, as well as results using the Scorpio (Stryker) and Profix (Smith + Nephew) total knee replacement systems. Patients were evaluated according to a radiographic protocol, a modification of the Knee Society total knee arthroplasty x-ray evaluation and scoring system. All patients had long leg standing x-rays in full extension and neutral rotation. Lateral x-rays were taken in neutral rotation with a maximum of 10 degrees of flexion. The femoral varus/valgus alignment is recorded on the AP x-ray as the Alpha angle, and the tibial alignment as the Beta angle. On the lateral x-ray the Gamma angle records the femoral flexion and the Theta angle the tibial prosthesis alignment along the tibial shaft.

Results: The results were statistically analysed by the Department of Statistics at the University. Results were stratified according to both the instrumentation used and the surgeon. These showed that there was no statistical difference between the alignment of the different prostheses, irrespective of the surgeon performing the procedure.

Conclusion: From this study we concluded that no one set of instrumentation used while performing a total knee replacement was superior to another. As long the surgeon is familiar with the instrumentation the final alignment of the prosthesis will be satisfactory.

Introduction and Aims: Uni-compartmental knee replacements are an alternative to total knee replacements in the management of uni-compartmental osteoarthritis of the knee. The aim of the study was to review the results of our first 60 patients.

Method: We assessed all patients both clinically and radiologically. To expedite the radiological assessment we devised a simplified scoring system. The mean follow-up was 18 months, nine patients had bilateral procedures. The mean age was 66 years, ranging from 45 to 83 years. Eightly-six percent were female. Primary osteoarthritis was the pathology in 93% and post-traumatic arthritis in 7%.

Results: Our average range of movement increased from 113 degrees to 120 degrees post-operatively. Our complicationns included one deep venous thrombosis, one patient with bilateral tibial component loosening and three patients with loose cement particles in the joint. A full radiological assessment was done to assess positioning of the prostheses as well as the interfaces. There was an improvement in the average radiological scoring when comparing the first and the last 10 patients.

Conclusion: Uni-compartment knee replacements are an interesting alternative to total knee replacements. Patient selection is critical. There is a significant learning curve, as demonstrated by the improved radiological scoring later in the series, particularly with regard to cementing techniques. Attention needs to be paid to removing all loose cement from the joint. The complication rate remains low and the results are satisfactory.

Introduction and Aims: Rapidly progressive lytic lesions of the calcar develop under the collar of cemented titanium femoral stems inserted in our unit. Progression of the defects slowed after reaching a critical size. Biopsies showed granulomatous lesions with polyethylene particles and multi-nucleate giant cells. The aim of the study was to determine the natural history of these lytic lesions.

Method: We developed a finite element analysis model. We determined the parameters of the FEA model, to reflect the geometry and physical characteristics of the prosthesis-bone construct and also factored in both loading and non-loading parameters. We also determined the characteristics of titanium and cobalt-chrome prostheses.

Results: We determined from the FEA model that there is some vertical displacement of the collar relative to the calcar-cement construct. This displacement is larger in the titanium than the cobalt-chrome model. The magnitude of the displacement is larger than the average polyethylene particle size. On loading and non-loading this displacement allows the development of a pump action, thus concentrating polyethylene particles under the collar of the prosthesis and leading to the granulomatous lytic lesions. The FEA studies demonstrated that the pumping action of the collar became less efficient, but did persist, as the lytic lesions increased in size.

Conclusion: We have explained the development of calcar lytic lesions under the collar of femoral stems. A pump action is present in loading and non-loading phases, sucking in polyethylene particles and allowing granulomatous lesions to form. We recommend caution when using collared femoral prostheses, more so titanium than cobalt-chrome, because of the development of calcar lytic lesions.

Introduction and Aims: The purpose of the study was to determine whether the addition of screws improved the fixation of the tibial base plate when using an uncemented total knee replacement.

Method: In June 1999 a prospective randomised double blind study on tibial base plate fixation was started at our institution after Ethics Committee approval. Patients were randomly allocated to either having or not having supplementary screws inserted through the base plate. To date, 138 arthroplasties have been performed and 119 are available for study. Of these, 56 have screws through the base plate and 63 do not. Assessment was of the position of the components of the prostheses, as well as the presence of any radiological lucent lines.

Results: The study is ongoing, and updated results will be presented. After a minimum of 12 months follow-up, 27 patients have some radiolucent lines at the prosthesis-bone interface on the tibial component of the knee replacement. Fourteen occurred where screws had been used and 13 when screws had not. One tibial tray subsided into the tibia without failure of fixation. No screws had been used in this case. Statistically no difference could be demonstrated between the two groups.

Conclusion: The early results of our study question the value of supplementing base plate fixation in uncemented total knee replacements, especially considering the additional cost of the screws and the potential detrimental consequences of the screws.

Introduction and Aims: Severe central fracture dislocations of the hip in the elderly can be catastrophic events. Conservative treatment yields poor results with stiff painful hips. We assessed the results of three patients treated with a total hip replacement for a central fracture dislocation of the hip, using ante-protrusio supports and bone grafts.

Method: Three elderly patients with central fracture dislocations were treated with early total hip replacement utilising ante-protrusio supports. Bone grafting was used to re-establish acetabular bone stock. Intra and post-operatively these patients had no more complications than a comparable group undergoing hip replacement for femoral neck fractures. The surgical times were longer than for routine hip replacment, and blood replacement requirements was slightly higher. Patients were mobilised early and aggressively.

Results: All became independent walkers. All regained a good range of movement. Radiologically the acetabular/pelvic fractures united and good bone-implant interfaces were obtained. There was no excessive heterotrophic bone formation. The economic assessment indicated that it was more cost-effective to treat these patients with a hip replacement than with alternative methods.

Conclusion: We regard total hip replacements in the management of acetabular fractures in the elderly as a reasonable approach, enabling our patients to mobilise early and keeping morbidity to an acceptable level. The procedure is also more cost-effective than internal fixation and delayed arthroplasty.

Introduction and Aims: Differing methods of cup fixation in total hip replacement are recommended. This prospective randomised study aims to show whether one method is superior to another.

Method: A prospective randomised double blind study was started in 1995, with Ethics Committee approval. Four different methods of cup fixation were used viz. a cemented Ogee cup, a press fit metal-backed cup with pegs, a press fit cup without pegs and a truncated screw in cup. Patient selection was confined to unilateral osteoarthritis of the hip and all other components used were standard viz cemented Elite Plus stem, 28mm ceramic head and Enduron polyethylene.

Results: One hundred and thirty-nine patients have been entered into the study, 23 were lost to follow-up leaving 116 for analysis. The cups have been radiologically assessed for acetabular orientation and the presence or absence of radiolucent lines or acetabular loosening. Follow-up ranges between one and nine years, and as the study is ongoing, updated data will be presented. Currently there are radiolucent lines appearing in zones 1, 2 and 3 of the Ogee cups, but none in the metal-backed cups. To date no cup has come loose.

Conclusion: Early results show that no method of cup fixation is superior to the other, although the radiolucent lines with the Ogee cups (cemented cups) is a cause for concern in the future.

The aim of this study was to measure polyethylene wear in uncemented metal-backed cups and compare it with cemented ultra-high molecular weight (UHMW) polyethylene cups in a controlled double-blind study.

The study group was made up of 91 patients aged 50 to 70 years undergoing THR for unilateral OA of the hip between February 1995 and July 2002. The male to female ratio was 40:60. In all patients, a cemented stem and 28-mm ceramic head was inserted, using a third-generation cementing technique and UHMW polyethylene. Patients were randomly allocated to receive either a cemented or uncemented acetabular cup. Eight patients were lost to follow-up.

Cemented cups were used in 28 patients (mean age 64 years). The mean thickness of the polyethylene was 9.6 mm (7.5 to 12.5). The mean liner thickness in the metal-backed cups was 8.9 mm (7 to 12.2). In measuring wear, baseline 3-month postoperative radiographs were compared with the most recent follow-up radiographs and Martell software was used.

The polyethylene in metal-backed cups had a mean wear rate of 0.49 mm at 4.7 years, with a mean annual wear rate of 0.12 mm. The cemented polyethylene cups had a mean wear rate of 0.45 mm at 5.3 years, with a mean annual wear rate of 0.11 mm.

The study is ongoing. Currently we conclude that there is no significant difference in the annual wear rate of polyethylene in uncemented metal-backed cups and cemented cups.

Introduction and Aims: To determine whether polyethylene wear is different comparing cemented polyethylene cups with metal-backed cups and a polyethylene insert.

Method: A sample of patients who had hip replacements between February 1995 and July 2002 have been studied. They were randomly allocated to either a cemented polyethylene cup or a metal-backed press-fit cup and polyethylene insert. All patients had a cemented stem and a 28mm ceramic head inserted. Ninety-one patients were treated, and 83 are available for analysis. The pre-operative diagnosis in all was unilateral osteoarthritis. The trial is a prospective randomised one and patients have been assessed clinically and radiologically annually. Twenty-eight patients with cemented polyethylene cups and 55 patients with uncemented metal-backed cups have been analysed. The polyethylene thickness of the cemented cups is 9.6mm on average, and the metal-backed cups had an average liner thickness of 8.9mm. Wear measurements were done using the Martell computer system.

Results: Based on measurements done on acetabular cups with the longest follow-up, the metal-backed cups have an average wear of 0.65mm, with an annual wear rate of 0.14mm. The cemented cups have an average wear of 0.64mm, with an annual average of 0.12mm. The study is ongoing and data will be updated.

Conclusion: Wear measurements were done using the three-month post-operative x-ray as the baseline and the most recent follow-up x-ray. Based on measurements done on cups with the longest follow-up, there is very little difference between the two groups. The study is ongoing and data will be updated.

Osteolysis and subsequent mechanical loosening often occurs in hip arthroplasties using polyethylene-on-ceramic (POC) bearings. This has prompted an ongoing search for alternative bearing surfaces. Ceramic-on-ceramic (COC) and metal-on-metal (MOM) prostheses are widely used, with good clinical results. Using hip simulator studies, we compared ceramic-on-metal (COM) and MOM prostheses.

We found COM pairings had 100-fold lower wear rates than MOM. The wear particles from both articulations were oval to round in shape and in the nanometer size range, with the COM producing smaller particles than the MOM. In both pairings, particle size decreased as the bearings bedded in. The volumetric particle loads were far smaller with COM bearing-surfaces than in currently-used MOM prostheses.

These findings have encouraged us to investigate the use of these novel bearing surfaces. Ethical approval has been obtained, and a prospective randomised clinical trial comparing POC, MOM, COC and COM bearing surfaces has started.

The assessment of large allografts in acetabular reconstruction surgery is notoriously difficult. Because of their invasive natures, methods such as tetracycline-labeled histological examination are not recommended. Radio-isotope studies are unreliable in assessing the degree of incorporation because labeled tissues remain hot for extended periods. CT scans are impractical because of the scatter generated by the metallic prosthetic components.

We used DEXA to assess the quality of large acetabular bone grafts immediately after surgery and at regular intervals thereafter. Software programmes were used to subtract the prosthetic components and give values for the remaining bony structure. DEXA results confirmed the initial adequacy of our grafting techniques. Serial scans showed the response of the grafts to both revascularisation and loading. Increases in high-load areas were higher than in low-load areas, reflecting the response of live bone to in vivo stresses. There were also changes reflecting the ongoing revascularisation of the grafts. These findings were born out by radiographs.

DEXA is useful in assessing the incorporation and biological responses of large allografts in revision arthroplasty.

Introduction and Aims: Many authors believe that patellar resurfacing decreases the incidence of anterior knee pain. We analysed the result of 150 of our own patients.

Method: Over the past four years we performed 150 total knee arthroplasties. None of the patellae were resurfaced, osteophytes were carefully removed, the patellae debrided, a thorough peri-patellar synovectomy and circumpatellar cautery denervation performed. All patients were examined by a consultant and a registrar to determine the site of any pain complaint. If there was any controversy a third surgeon was consulted.

Results: No patient had pain severe enough to warrant revision surgery. Only two patients had anterior knee pain, and in neither was it marked.

Conclusion: We do not know whether our favourable results are attributable to the patellar management, or due to the prosthesis used. We concede that a prospective randomised trial is necessary to determine this, but with such a low incidence of patellar complications we feel this is not ethically justified.

Over five years, 85 low-cost primary total arthroplasties (Eortopal Bulteamex) were done at a referral hospital. These were followed up for a mean of 48 months (minimum of 18 months). There were 11 revisions (13%), with four (4.7%) necessary for aseptic loosening, two (2.3%) for recurrent dislocations, four (4.7%) for sepsis and one (1.3%) for a periprosthetic fracture.

When these results were compared with the Trent Regional Arthroplasty Register, the revision rate was noted to be four times higher than in the Trent study, with aseptic revisions being twice as high and infection rates three times higher. Dislocation rates were half those in the Trent study. We concluded that our lower dislocation rate probably reflected the quality of our surgery. Our higher sepsis rate was probably related to the hospital environment, and the high aseptic loosening rate due to the quality of the ‘low-cost’ prosthesis.

We conclude that to be cost-efficient, ‘low-cost’ pros-theses must be of good quality and that the hospital environment must be optimal. This study highlights the need for an Arthroplasty Register in South Africa.

Four low-cost hip prostheses, explanted because of clinical failure within three years, were subjected to a retrieval analysis study to determine the cause of the early failure. The study aimed to determine whether the low-cost prosthesis was substandard and had consequently contributed to the need for early revision. The retrieval analysis included a photographic record, a fractographic examination, an analysis of the material composition of the components, and a mechanical property analysis. These investigations were done in accordance with the ASTM F561 standards.

Results demonstrated substandard qualities in respect of all parameters analysed. We conclude that the inferior quality of these low-cost hip prostheses contributed appreciably to their early failure and revision.

We have previously reported on early lytic lesions occurring when collared titanium prostheses are used. Previous finite element analysis studies (FEAs) showed that lytic lesions of the calcar were due to concentration of polyethylene wear particles under the collar by a ‘pumping action’. Further follow-up of these calcar lytic lesions showed that their rate of increase in size progressively slowed down. Further FEAs were performed to determine why this was so.

An FEA mesh construct was developed, incorporating the new parameters of no contact between the collar and the calcar bone. A mechanical model to determine displacement parameters was also developed. These FEA studies demonstrated that the pumping action of the collar became less efficient as the size of the lytic lesions increased. This led to less concentration of polyethylene particles under the collar and fewer granulomatous reactions. The change in the proximal prosthesis-cement-bone construct may lead to cement mantle deterioration and earlier failure. We still recommend caution when a collared prosthesis is used, and the material and geometry of the prosthesis remain important.

Complex acetabular defects after failed total hip arthroplasty (THA) remain a major challenge in revision surgery. We managed 29 patients, of whom 27 had type-III and two type-IV defects (AAOS classification).The mean age of the 16 men and 13 women was 68 years (22 to 96).

Use of a modular uncemented acetabular revision system allowed us accurately to position the construct, and then optimise the orientation of the polyethylene liner in respect of stability in the reduced hip. The modularity of the system allowed good access to do an impaction bone graft to restore the defects in the bone stock.

Our follow-up ranged from 2 to 25 months. The orientation of the acetabular construct was measured radiologically and was at 50°. Our complications included four dislocations, two transient nerve palsies, one deep infection, four deep venous thromboses and one death from a pulmonary embolism. We conclude that the use of a modular acetabular reconstruction system is promising in these extremely difficult cases.

We managed three elderly patients who had central fracture dislocations with early total hip arthroplasty (THA), using anteprotrusio supports. Bone grafting was used to re-establish acetabular bone stock.

Intraoperatively and postoperatively, these patients had no more complications than did patients undergoing THA for hip fractures. However, the surgical times were longer than for routine THA and blood replacement was slightly higher. Patients were mobilised early and aggressively. All became independent walkers and regained good range of movement. Radiologically the acetabular/pelvic fractures united and good bone-implant interfaces were established. There was no excessive heterotrophic bone formation.

We regard THA in the management of acetabular fractures in the elderly as a reasonable approach, enabling patients to mobilise early and keeping morbidity to an acceptable level.

In June 1999 we instituted a prospective, randomised, double blind study to determine whether in the use of the Profix® total knee replacement system the addition of screws improved the fixation of the tibial base plate. There were 145 arthroplasties in 137 patients, 77% of them female. Their mean age was 66 years. In 86% of the patients there was osteoarthritis and in 14% an inflammatory arthritis. On a random basis, supplementary screws were inserted through the base plate into the tibia in 49% of arthroplasties and the remaining 51% were not fixed. In both groups the postoperative femoral angle measured 95% and at 12-month evaluation the tibial angle measured 89°, giving a total valgus angle of 6°. To date no tibial base plates have come loose. It is felt that the large central titanium peg plays a major role in assisting fixation of the base plate to the tibia and that supplementary screws are unnecessary. There is a small cost saving when screws are not used. We postulate that one may in the future minimise polyethylene debris tracking and osteolysis.

Anterior knee pain after total knee arthroplasty (TKA) occurs in 5% to 30% of patients whether or not the patella has been resurfaced. We retrospectively reviewed our patients, none of whom underwent patellar resurfacing. Only 2% had anterior knee pain, none requiring revision surgery. Our follow-up was between two and five years.

We paid particular attention to removing osteophytes and conducting a thorough peripatellar synovectomy and a circumpatellar cautery denervation.

Our results compare favourably to those in the literature, whether or not the patellae were resurfaced. We conclude that patellar resurfacing in TKA is unnecessary when careful attention is paid to the peripatellar tissues.

Complex acetabular defects after failed total hip arthroplasty (THA) remain a major challenge in revision surgery. We managed 29 patients, of whom 27 had type-III and two type-IV defects (AAOS classification). The mean age of the 16 men and 13 women was 68 years (22 to 96).

Use of a modular uncemented acetabular revision system allowed us accurately to position the construct, and then optimise the orientation of the polyethylene liner in respect of stability in the reduced hip. The modularity of the system allowed good access to do an impaction bone graft to restore the defects in the bone stock. Our follow-up ranged from 2 to 25 months. The orientation of the acetabular construct was measured radiologically and was at 50°. Our complications included four dislocations, two transient nerve palsies, one deep infection, four deep vein thromboses and one death from pulmonary embolism. We conclude that the use of a modular acetabular reconstruction system is promising in these extremely difficult cases.

Resorption of the calcar below the collar of a titanium femoral prosthesis was observed. Biopsies of these lesions showed concentrations of polyethylene. We assessed the size of the resorption and correlated this with the size of the femoral prosthesis and the time since implantation. The age and the weight of the patient were also linked to the size of the prosthesis.

We conducted a finite element analysis (FEA) of the femoral component-femur complex in both the loaded and unloaded situation. The FEA study demonstrated changing pressure under the collar that can be translated into microbending motions, with the degree of the movement dependent on the size of the prosthesis, the material of the prosthesis and the weight of the patient.

We hypothesise that the existence of a ‘polyethylene pump’ due to the bending movements of the collared prosthesis concentrates polyethylene particles under the collar. We therefore postulated that the calcar resorption is due to the polyethylene granulomatous lesions, resulting from the micromotion of the collar of the prosthesis.

We have introduced a radiological scoring system to assess our technical competence in hip replacement surgery. We have also used it to assess the progress of the registrars in our training programme.

This scoring method involves several parameters, including positioning of the components and the quality of interfaces. We compared our results before and after the introduction of this scoring system, and found that the quality of our surgery had improved. We conclude that an objective scoring system is valuable as a training aid, as well as in maintaining standards in our unit.

Over five years, 85 low-cost primary total arthroplasties (Eortopal Bulteamex) were done at a referral hospital. These were followed up for a mean of 48 months (minimum of 18 months). There were 11 revisions (13%), with four (4.7%) necessary for aseptic loosening, two (2.3%) for recurrent dislocations, four (4.7%) for sepsis and one (1.3%) for a periprosthetic fracture.

When these results were compared with the Trent Regional Arthroplasty Register, the revision rate was noted to be four times higher than in the Trent study, with aseptic revisions being twice as high and infection rates three times higher. Dislocation rates were half those in the Trent study. We concluded that our lower dislocation rate probably reflected the quality of our surgery. Our higher sepsis rate was probably related to the hospital environment, and the high aseptic loosening rate due to the quality of the ‘low-cost’ prosthesis.

We conclude that to be cost-efficient, ‘low-cost’ prostheses must be of good quality and that the hospital environment must be optimal. This study highlights the need for an Arthroplasty Register in South Africa.

Severe central facture dislocations of the hip in the elderly can be catastrophic. Conservative treatment yields poor results with stiff painful hips. Reasonable hip function may be achieved with multiple surgical procedures and extended periods of immobilisation, but morbidity and mortality remain high.

We managed three elderly patients who had central fracture dislocations with early total hip arthroplasty (THA), using anteprotrusio supports. Bone grafting was used to re-establish acetabular bone stock.

Intraoperatively and postoperatively, these patients had no more complications than did patients undergoing THA for hip fractures. However, the surgical times were longer than for routine THA and blood replacement was slightly higher. Patients were mobilised early and aggressively. All became independent walkers and regained good range of movement. Radiologically the acetabular/pelvic fractures united and good bone-implant interfaces were established. There was no excessive heterotrophic bone formation.

We regard THA in the management of acetabular fractures in the elderly as a reasonable approach, enabling patients to mobilise early and keeping morbidity to an acceptable level.

In June 1999 a randomised double-blind study on tibial base plate fixation was started to determine whether, when using the Profix® total knee replacement, the addition of screws improved the fixation of the tibial base plate. To date 138 total knee arthroplasties (THAs) have been performed, 119 of which were available for study. Selected randomly, 56 patients had supplementary screws inserted through the base plate and 63 did not.

After a minimum of 12 months follow-up, 27 patients had some radiolucent lines at the prosthesis-bone interface on the tibial component. These lines occurred in 14 cases with supplementary screws and 13 without screws. In one patient without supplementary screws, the tibial tray had subsided into the tibia. Statistically there was no apparent difference between the two groups.

The early results of our study raise questions about the value of supplementing base plate fixation in uncemented THAs, especially considering the additional cost of the screws and their potentially detrimental consequences.

Primary total hip replacements are routine procedures with good outcomes. To ensure uniformly good results it is important that a thorough preoperative assessment of the patient is made. The prosthesis best suited to the patient and the pathology must be carefully selected and the optimal surgical technique must take into account patient, pathology and prosthesis parameters.

We discuss patients’ problems such as morbid obesity, the different arthritides and neuromotor abnormalities. Acetabular problems, including dysplastic acetabula and acetabula protrusio, are dealt with in detail. We examine post-traumatic hip pathologies, including retained fracture implants, nonunions and ankyloses. On the femoral side, dysplastic femurs, post-traumatic malunions and post-osteotomies are dealt with.

We have introduced a radiological scoring system to assess our technical competence in hip replacement surgery and the progress of the registrars in our training programme. The scoring method involves several parameters, including positioning of the components and the quality of interfaces.

We compared our results before and after the introduction of this scoring system, and found that the quality of our surgery had improved. We conclude that an objective scoring system is valuable as a training aid, as well as in maintaining standards in our unit.

Resorption of the calcar below the collar of a titanium femoral prosthesis was observed. Biopsies of these lesions showed concentrations of polyethylene.

We assessed the size of the resorption, correlating it with the size of the femoral prosthesis and the time since implantation. The age and the weight of the patient was also linked to the size of the prosthesis.

We conducted a finite element analysis (FEA) of the femoral component-femur complex in both the loaded and unloaded situation. FEA demonstrated changing pressure under the collar. This can be translated into micro-bending, with the degree of movement dependent on the size of the prosthesis, the material of the prosthesis and the weight of the patient.

We postulate the existence of a ‘polyethylene pump’ owing to the bending motion of the collared prosthesis, and that calcar resorption is due to the resultant polyethylene granulomatous lesions .

Where reconstruction is deemed impossible, excision of the radial head has been the mainstay of treatment for shattered radial head and neck fractures. While some patients seem to do well after the procedure, some develop progressive instability and pain because of proximal translocation of the radius. We looked at a new procedure in which a metal radial head is inserted to provide greater stability after the excision. Historically silicone prostheses have been used, but these were found to fail dramatically after a time.

We recruited 11 patients requiring radial head replacements. Their ages ranged from 26 to 54 years. In five patients the dominant arm was affected. The radial head was deemed non-reconstructable in all patients, and the alternative method of treatment would have been radial head excision. In one patient, radial head replacement was performed 14 years after previous radial head excision. A standardised procedure was performed, replacing the radial head with an Evolve modular radial head prosthesis.

At follow-up, we assessed patient satisfaction, range of movement, overall stability of the prostheses, grip strength and return to full activity. The postoperative range of movement was assessed at three and six weeks, and the outcome in terms of mobility at six months. Supination ranged between 40( and 90( and pronation between 40( and 85(. Elbow extension ranged between -5( and -30 and flexion between 100( and 150(.

We concede that the follow-up period has been short, but early results suggest that radial head replacement may be a good option in patients in whom radial head reconstruction is not possible.

Many authors believe that patellar resurfacing decreases the incidence of anterior knee pain. We analysed the results of 98 of our own patients (103 knees).

Over the past two years, we performed total knee arthroplasty on 23 men (one bilateral) and 75 women (four bilateral). None of the patellae were replaced, but we carefully removed osteophytes, debrided the patella, and performed a thorough peripatellar synovectomy and circumpatellar cautery denervation. All patients on our database were telephoned, and those who reported pain were examined independently by a consultant and a registrar. If there was any controversy about the site of the pain, a third surgeon saw the patient.

No patient had pain severe enough to warrant revision surgery. Only two (2%) had anterior knee pain, and in neither of them was it marked.

We do not know whether our favourable results are attributable to the peripatellar synovectomy and/or circumpatellar cautery denervation. While we concede that a control study of patients who have undergone patellar resurfacing might be necessary before a firm conclusion can be drawn, we question whether, with such a low incidence of patellar problems, this is ethically justifiable.

Between January 1990 and October 2000, 108 total hip arthroplasties using a cemented polished titanium stem and a cemented ultra-high molecular weight polyethylene (UHMWP) cup were performed at our hospital. Because during routine follow-up visits we noted instances of resorption of the calcar, we decided to assess whether this was a problem. We were able to assess 85 of the original 108 hips.

Calcar resorption was observed in 43 hips. The extent of calcar resorption varied from 1 mm to over 15 mm. In one patient a biopsy showed typical polyethylene granuloma.

Because there is a risk of long-term failure, we concluded that it is inadvisable to use a cemented polished titanium stem when UHMWP is one of the bearing surfaces.

We present five case studies of a new technique for the treatment of distal femur fractures after total knee arthroplasty. This type of fracture is rare, but when it occurs can present a dilemma as to the correct treatment. If the prosthesis is loose, the logical treatment is revision surgery with the use of long stem stabilisation. If the prostheses are firmly fixed, the best method of treatment is difficult to determine. Intramedullary fixation is a well-known modality, but proper fixation distal to the fracture can be problematic in very distal fractures.

We performed intramedullary fixation of these fractures, using standard retrograde condylar locking nails inserted through the notch of the femoral prostheses. The problem of distal fixation was solved by fixating the nail to the femoral prostheses with a plate that fitted into the notch of the pros-theses and was securely fixed to the nail with a custom-made screw. This not only gave alignment stability but also aided in compression of the fracture. A locking screw distal to the fracture line was inserted in some patients to aid fixation. but could not be placed in others owing to the distal position of the fracture. Autograft was used in most cases to aid fracture healing. Postoperatively the leg was immobilised in a cast for six weeks.

This method of fixation of the nail to the prostheses has not been described in the literature to date. We believe that this technique offers a new modality in treating these complex fractures, providing adequate fixation, alignment and compression stability.