Aims

The aim of this study was to present the first retrieval analysis findings of PRECICE STRYDE intermedullary nails removed from patients, providing useful information in the post-market surveillance of these recently introduced devices.

Background

In the late 1980's Michael Freeman conceived the idea that knee replacement would most closely replicate the natural knee joint, if the medial Tibio-Femoral articulation was configured as a “ball-in-socket”. Over the last three decades, medial rotation and medial pivot designs have proved successful in clinical use. Freeman's final iteration of the medial ball-in-socket concept was the Medial Sphere knee. We report the three-year survivorship, clinical outcomes, patient reported outcome measures (PROMs) and radiographic analysis of this implant in a multi-centre, multi-surgeon, prospective observational study.

Additive manufacturing has enabled a radical change in how surgeons reconstruct massive acetabular defects in revision hip surgery. We report on the early clinical and radiological results from our methods for surgical planning, design, and implantation of 3D printed trabecular titanium implants in a cohort of patients with large unclassifiable pelvic defects.

We set up a prospective investigation involving 7 consecutive patients. Inclusion criteria was the following: 1) A history of previous total hip replacement; and 2) Current imaging showing at least a Paprosky 3B defect. Planned acetabular inclination and version was 40° and 20° respectively. Post operatively all patients had a CT scan which was analysed with software to determine component position and compared to planned. Outpatient review was done at 2 weeks (For wound), 6 weeks (for weight bearing and fixation) and 52 weeks (for fixation and infection) post-operative.

The median age at surgery was: 65 years (40–78). The median bone defect volume was 140cm³. Median surgery length was 5.2 hours (3–6.25). Median blood loss was 1300mL (450– 2000). Radiologically, components were stable and no screw breakages were identified. Achieved inclination was 41.0° (29.0–55.6) and achieved version was 15.8° (3.8–43.6). Median Oxford Hip score improved from 9 (2–44) to 25 (18–32).

We have demonstrated a new series of pre, intra and post-operative methods for reconstruction of unclassifiable acetabular bony defects. Initial clinical and radiological results are excellent considering the severity of the bony defects. We recommend the use of our or similar methods when trying to reconstruct these defects.

Introduction:

Non-invasive extendible endoprostheses (NIEE) were primarily developed for salvage after musculo-skeletal tumour surgery in the immature skeleton. However, they may also have a unique application to manage complex limb reconstruction in revision surgery to address limb-length inequality in the mature skeleton. The aim of this study is to present the minimum 2 –year results of using non-invasive extendible endoprostheses for complex lower limb reconstruction.

Introduction:

Pigmented Villonodular Synovitis (PVNS) is a rare inflammatory disorder of the synovium, bursa and tendon sheath. The objective of this study was to evaluate the long-term outcomes and morbidity associated with operative management of PVNS of the hand.

Introduction:

Endoprosthetic replacement of the proximal femur is common in the management of bone tumours and failed revision arthroplasty. This study seeks to compare those patients undergoing acetabular resurfacing at the time of femoral replacement with those patients where the native acetabulum was preserved.

Introduction:

Distal femoral replacement is recognised as the optimum treatment for malignant distal femoral tumours. Aseptic loosening is known to be a major cause for failure in these implants. Studies have indicated that the HA coated collar promotes osteointegration and bony in growth. This study compares long term aseptic loosening in implants with HA coated collars to those without in the immature skeleton.

Introduction:

High failure rates with large diameter, metal on metal hip replacements have highlighted a potential issue with the head/stem taper junction as one of the significant sources of metal ion release. Postulated reasons as to why this may be such a problem with large head metal on metal hip replacements is due to the increased torque achieved by the larger head size. This may be responsible for applying greater micromotion between the head and stem taper and consequently greater amounts of fretting corrosion. The aim of this study was to perform short term in vitro electrochemical tests to assess the effect of increasing head diameter and torque on the fretting corrosion susceptibility of the head/stem taper interface and to investigate its effect on different material combinations.

Background

The changes in surface roughness occurring during the wear process at the bearing surface are of great importance in trying to understand the failure mechanism of large head metal-on-metal hip replacements. The aim of the study is to identify and characterise the areal surface parameter variation between the worn and unworn areas. Surface topography variations at the bearing surface have an effect on the lubrication regime [1]. In vitro tests of these components have suggested a “self-polishing” of the surface [2]. Traditionally Ra has been used as a descriptor of surface texture. Considering the high standard of manufacturing to which these components are produced, Ra is not sufficient to describe surface morphology which requires spatial information which can only be achieved through the use of areal parameters.

Introduction

Local recurrence of tumours along the biopsy tract is a known complication of percutaneous closed needle biopsy. Correct surgical management requires preoperative identification and excision of the biopsy tract at time of surgery. These tracts become increasingly difficult to identify with time, leading to risk of inadequate excision of the biopsy tract and recurrence of the tumour at the biopsy site.

The articulating surface replacement (ASR) XL stemmed total hip replacement and ASR resurfacing hip systems were recalled by DePuy due to a high prevalence of early failure. The ASR XL has a greater failure rate than the ASR resurfacing, which has been increasingly attributed to wear and corrosion at the taper interface between the female taper surface of the femoral head and the male taper (trunnion) of the femoral stem. The aim of this study was to quantify the prevalence and severity of taper corrosion in retrieved ASR XL hip components.

A peer-reviewed subjective corrosion scoring system was used to quantify corrosion in a consecutive series of the 50 ASR XL hip components (head components – n=44; femoral stems – n=6) at our retrieval centre. Bearing surface wear (femoral head and acetabular cup combined) was quantified and a value of <5 microns was defined as low-wearing. Subsequent profilometry analysis was undertaken in the low-wearing hips to quantify material loss from the taper interface.

90% of components showed evidence of corrosion, with at least moderate corrosion observed in 58%. There were 17 low-wearing hips which had a median material loss from the taper interface of 3.51mm³ (range: 0.612–9.443). The median linear depth of material loss was 33μm (range: 8.5–78.0). No relationship was observed between taper corrosion and serum cobalt (r=0.204, p=0.2712) or chromium (r=0.146, p=0.432) metal ions.

Wear and material loss from metal-on-metal (MoM) hips is associated with pseudotumour formation and adverse soft-tissue reactions. We have shown that taper corrosion is extremely common in failed ASR XL hips and that wear occurs in the same degree of magnitude as at the bearing surface also occurs at the taper interface. Therefore our findings support the emerging concept of ‘taper failure’, whereby the taper is the predominate reason for failure of MoM hips. Future work must determine the relative contributions of the bearing surface and the taper interface to serum cobalt and chromium metal ion levels.

Corrosion at the taper interface between the femoral head and the femoral stem is well described in metal-on-polyethylene (MoP) hips but previously was undetermined in large diameter head metal-on-metal (LHMoM) hips. The high failure rate of the articulating surface replacement (ASR) XL hip system has been partly attributed to susceptibility to corrosive damage at the taper interface. It was not known if other hip manufacturers are liable to taper corrosion. Therefore the aim of this study was to quantify the prevalence and severity of taper corrosion in LHMoM hips and compare corrosion across five different current generation manufacturers.

Taper corrosion was analysed in a consecutive series of the five most common hip types at our retrieval centre: ASR XL, DePuy (n=49); Birmingham hip resurfacing, Smith & Nephew (n=33), Durom, Zimmer (n=31), M2a Magnum, Biomet (n=14) and Cormet, Stryker (n=10). A four-scale peer-reviewed qualitative corrosion scoring system was used to quantify corrosion (none, mild, moderate and severe).

Evidence of corrosion was observed in 86% of components, with at least moderate corrosion observed in 61%. No difference in corrosion was observed between the ASR XL and the other manufacturers (p=0.202). There was still no difference seen when all manufacturers were compared individually (p=0.363). A positive correlation was observed between corrosion and femoral head diameter (r=0.224, p=0.021). However no relationship was observed with implantation time (r=0.163, p=0.118).

Our study indicates that taper corrosion is common in LHMoM hips and affects all hip types equally. The clinical significance of this finding is that all hip types will be susceptible to the complications of corrosion, such as third body wear and osteolysis. Furthermore recent reports indicate that corrosive debris released from the taper interface may play a role in the formation of pseudotumours and adverse soft-tissue reactions. We found that larger femoral head sizes showed greater corrosion, which suggests that high torque increases fretting corrosion of the taper interface. Future work must determine the optimum femoral head size and investigate the chemical composition of the corrosive debris.

In metal-on-metal (MoM) total hip arthroplasty, the taper interface is where the femoral head (female taper surface) attaches to the trunnion (male taper) of the femoral stem. Corrosion is well reported in metal-on-polyethylene hips but little is known about taper corrosion in MoM devices. The aim of this study was to quantify corrosion in modern-generation stemmed MoM hip systems and gain insight into the nature of the underlying corrosive attack.

Taper corrosion was quantified in 161 failed MoM components (head components n=128; femoral stem n=33) from nine hip types with the use of a qualitative subjective scoring system. An unanticipated finding on preliminary inspection of the hips was a region on the female taper surface that contained ridges that directly corresponded with the ridged microthread on the trunnion. The ridges were not present on unimplanted (control) female taper surfaces and therefore a novel four-scale subjective scoring system was devised to quantify the prevalence and severity of this ‘imprinting’ phenomenon.

Evidence of corrosion was observed in 81% (131/161) of components, with at least moderate corrosion observed in 58% (94/161). Corrosion was greater on the female taper surface than on the male taper (p=0.034) and the two scores were associated (r=0.784, p=0.001). Imprinting affected all manufacturers and was observed in 64% (82/128) of head components. The corrosion and imprinting scores were strongly correlated (r=0.694, p=0.001). Corrosion was largely confined to the area of the female taper interface where imprinting had occurred i.e. the region that had been in contact with the trunnion microthread. Scanning electron microscopy showed evidence of fretting corrosion and substantial mechanical wear within the ridged region on the female taper surface.

Our study indicates that MoM hips are susceptible to taper corrosion. We believe it occurs by a process of “mechanically-assisted crevice corrosion,” involving the following sequence of events: joint fluid enters the taper junction as a result of pumping of fluid along the machined microthread of the trunnion. This results in galvanic corrosion of the anodic surface (the cobalt-chromium femoral head or taper sleeve). The pattern of corrosion of the head taper is determined by the surface profile of the screw thread of the trunnion, thus leaving an imprinted appearance. Historically the ridged microthread was introduced to trunnions to minimise the risk of burst fracture of ceramic heads. However this study indicates that the ridges are detrimental in MoM hips by causing extensive mechanical wear. Thus the possibility that cobalt-chrome and ceramic femoral head components require different trunnion designs needs urgent investigation.

Patients with skeletal dysplasia are prone to developing advanced degenerative knee disease requiring total knee replacement (TKR) at a younger age than the general population. TKR in this unique group of patients is a technically demanding procedure due to the bone deformity, flexion contracture, generalised hypotonia and ligamentous laxity. We set out to retrospectively review the outcome of 11 TKR's performed in eight patients with skeletal dysplasia at our institution using the SMILES custom-made rotating-hinge total knee system. There were 3 males and 5 females with mean age 57 years (range, 41–79 years), mean height 138 cm (range, 122–155 cm) and mean weight 56 kg (range, 40–102 kg). Preoperative diagnoses included achondroplasia, spondyloepiphyseal dysplasia, pseudoachondroplasia, multiple epiphyseal dysplasia, morquio syndrome, diastrophic dysplasia and Larson's Syndrome. Patients were followed clinically and radiographically for a mean of 7 years (range, 3–11.5 years). Knee pain and function improved in all 11 joints. Mean Knee Society clinical and function scores improved from 24 (range, 14–36) and 20 points (range, 5–40) preoperatively to 68 (range, 28–80) and 50 points (range, 22–74) respectively at final follow-up. Four complications were recorded (36%), including a patellar fracture following a fall, a tibial periprosthetic fracture, persistent anterior knee pain and a femoral component revision for aseptic loosening. Our results suggest that custom rotating-hinge TKR in patients with skeletal dysplasia is effective at relieving pain, optimising movement and improving function. It compensates for bony deformity and ligament deficiency and reduces the need for corrective osteotomy. Patellofemoral joint complications are frequent and functional outcome is worse than primary TKR in the general population.

Submission endorsed by Mr Peter Calder, Consultant Orthopaedic Surgeon and Society member

Introduction

Edge loading is a common wear mechanism in Metal-on-Metal (MOM) hip resurfacing and is associated with higher wear rates and the incidence of pseudotumour. The purpose of this study was to develop a method to investigate the contributions of patient, surgical and implant design variables on the risk of edge loading.

Introduction

The aim of this study was to see if the evaluation of the initial postoperative radiograph following primary knee and hip arthroplasty correlated with clinical outcome at five years postoperatively.

Background

The Enhanced Recovery Programme (ERP) is an evidence based initiative aimed at speeding up patient recovery after major surgery and improving their outcomes. The Royal National Orthopaedic Hospital, Stanmore (RNOH) is a specialist orthopaedic and implemented an ERP for primary knee arthroplasties from October 2010.

Introduction

It has been speculated that impact deformation of thin 1-piece cups used for modern metal-on-metal hip replacement may contribute to early failure. The purpose of this study was to reproduce typical impact deformation and quantify the effect of this on the frictional torque generated at the hip.

Aims

Present the outcomes of those patients diagnosed with Ewing's Sarcoma of the foot within the past 10 years and treated at the Royal National Orthopaedic Hospital's Bone Tumour Unit, Stanmore.

Infection after knee arthroplasty is a devastating complication. Our aim is to present our outcomes of treating infected knee replacements at a tertiary referral centre.

We performed a consecutive, retrospective case series of all revision knee arthroplasty for infection between January 2006 and December 2008. Case notes were reviewed and data collated on the date and institution of primary arthroplasty, procedures undertaken at our institution, microbiology and bone loss post first stage, serological markers (C-reactive protein, ESR) prior to second stage and outcome.

During this three year period we performed 430 knee revision operations. 51 were in the presence of deep chronic infection. 90% were referred from other hospitals. Overall infection was successfully eradicated in 69%.

Nineteen patients underwent repeat two-stage and overall eleven (58%) patients had successful eradication of infection with multiple two-stages. Of these 47% had F3/T3, the highest grading of Anderson Orthopaedic Research Institute bone loss indicating no metaphyseal bone. A further 12% had bicondylar deficiency on the tibia and no femoral metaphyseal bone (F3/T2b).

Multidrug resistance present in 69% and 47% were infected with multiple organisms. All members of the unsuccessful outcome group had at least one multidrug resistant organism compared to 43% in the successful cohort (P=0.0002). Multiple organisms are associated with an unsuccessful outcome (P=0.056).

Serological markers were not significantly different between the successful and unsuccessful outcome groups.

Where the referring hospital had attempted revision and failed, the chance of eradicating infection dropped from 75% to 58% and the rate of above knee amputation was twelve times higher (3% vs. 36%).

Custom constrained, rotating hinge prostheses enable aggressive soft tissue debridement including ligaments. Successful two-stage requires a multidisciplinary approach including tissue viability nurses, microbiologists and plastic surgeons. Where units lack revision expertise this series suggests early referral increases the chance of limb salvage.

Introduction

Optimal results from uncemented total hip arthroplasty (THA) requires the prosthesis to obtain initial stability, restoration of biomechanics, bone contact along the ingrowth surface and uniform stress transfer to the proximal femur. Anatomic variation within the population makes this difficult to reproduce in every patient. To achieve optimal fit and fill of the proximal femur, options are reshaping the canal or creating an implant which precisely fits the patient's anatomy. The former increases bone loss and risks weakening the supporting bone, creating areas of stress concentration or shielding. Computer assisted design-computer assisted manufacture (CAD-CAM) femoral components were designed to overcome these issues. We present the long term results of CAD-CAM femoral components used in primary THA.

Chondral injuries of the knee are extremely common and present a unique therapeutic challenge due to the poor intrinsic healing of articular cartilage. These injuries can lead to significant functional impairment. There are several treatment modalities for articular osteochondral defects, one of which is autologous chondrocyte implantation. Our study evaluates the mid to long term functional outcomes in a cohort of 828 patients who have undergone an autologous chondrocyte implantation procedure (either ACI or MACI), identifying retrospectively factors that may influence their outcome.

The influence of factors including age, sex, presence of osteoarthritis and size and site of lesion have been assessed individually and with multivariate analysis. All patients were assessed using the Bentley Functional Score, Visual Analogue Score and the Cincinnati Functional Score. Assessment were performed pre-operatively and of their status in 2010.

The longest follow-up was 12 years (range 24 to 153 months) with a mean age of 34 years at time of procedure. The mean defect size was 409 mm² (range 64 to 2075 mm²). The distribution of lesions was 51% Medial Femoral Condyle, 12.5% Lateral Femoral Condyle, 18% Patella (single facet), 5% Patella (Multifacet) and 6% Trochlea. 4% had cartilage transplant to multiple sites.

High failure rates were noted in those with previous cartilage regenerative procedures or evidence of early osteoarthritis and those with transplantation to multiple sites.

Autologous chondrocyte implantation is an effective method of decreasing pain and increasing function, however patient selection plays clear role in the success of such procedure.

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora's lesion, is a rare condition characterised by the formation of surface-based osteocartilaginous lesions typically affecting the hands and feet. 22 cases were identified from the records of a regional bone tumour unit, dating from 1985 to 2009. Of 22 cases, 9 lesions involved the long bones of the hand, 7 the long bones of the feet, 1 case originated from a sesamoid bone of the foot and 5 from long bones (radius, ulna, femur [2] and tibia). Age ranged from 6 to 66 (mean: 31.8) and male to female ratio was 1.8:1. Diagnosis was based on combined radiological and histological features, and initial surgical treatment was excision in 21 cases, and 1 amputation. Follow-up ranged from 12–162 months (mean 32). Recurrence occurred in 6 patients (27%), with mean time to recurrence 49 months (range 10–120). 2 of 8 patients with complete resection margins developed recurrence (25%), versus 4 of 14 with marginal or incomplete resection (28%). Given the potential surgical morbidity inherent in resection, our data suggest that there may be a role for a relatively tissue-conserving approach to the excision of these lesions.

Introduction

The variability of the endosteal geometry after removal of the femoral component can make proximal fit difficult to achieve with an ‘off the shelf’ prosthesis. Whatever the anatomy of the proximal femur, it is important to achieve immediate stability, preserve bone stock and protect the femur from cortical defects which can lead to subsequent fracture. In revision Total Hip Arthroplasty (THA) this requires a large inventory of modular components. The use of custom computer-assisted design-computer-assisted manufacture (CAD-CAM) components negates this need. Little has been published on the use of custom-made components in revision THA. We report the results of a cohort of patients who underwent revision THA using CAD-CAM femoral components.

Introduction

Metal on metal hip resurfacing arthroplasty (MoM HR) has the highest revision rates according to the UK National Joint Registry. Revisions for lesions associated with soft tissue necrosis (pseudotumors) have been associated with poor outcomes. There is a relative paucity of information on early revision of painful HR prostheses. We present the results of a series of patients who underwent early revision of painful MoM HR procedures.

Background

It is known that excessive varus alignment of the femoral stem in total hip replacement (THR) creates a sub-optimal biomechanical environment which is associated with increased rates of revision surgery and component wear. Little is known regarding the effect of femoral stem alignment on patient functional outcome.

Introduction

There is no consensus on the ideal management of young, active patients with disabling coxarthrosis. Within this group, patients with femoral head defects secondary to cysts or avascular necrosis pose particular challenges. Resurfacing arthroplasty is contraindicated and the results of traditional total hip arthroplasty are suboptimal in this group. The BMHR was designed to offer a bone conserving option for these patients. We report the outcome of this device in the short term.

The surgical treatment of bone tumours can result in large perioperative blood loss due to their large sizes and hypervascularity. Preoperative embolisation has been successfully used to downgrade vascularity, thus reducing perioperative blood loss and its associated complications. Prior to embolization era, blood loss as high as 18,500mL have been reported peri-opratively.

Twenty-six patients with a variety of bone tumours (average size 10.5×7.5×5.5cm), who underwent pre-operative embolisation between 2005 and 2009, were retrospectively studied. The group comprised of 17 females and 9 males. Their mean age was 38 years old. All patients underwent surgical resection within 48 hours of embolization. Mean blood loss was 796mL and required on average 1.1units of blood. We experienced no complications.

Pre-operative arterial embolisation of large, richly vascular bone tumours in anatomically difficult positions, is a safe and effective method of downstaging vascularity and reducing blood loss.

Aims

Revision total hip arthroplasty is a common operation. The MP Link (Waldemar Link, Hamburg, Germany) system is a distally loading, modular, tapered femoral stem component for revision hip surgery. MP Link in revision total hip arthoplasty was investigated clinically, radiologically and with Oxford hip scores.

Introduction

Metal Artefact Reduction Sequence (MARS) MRI is being increasingly used to detect soft tissue inflammatory reactions surrounding metal-on-metal hip replacements. The UK MHRA safety alert announced in April 2010 recommended cross-sectional imaging such as MRI for all patients with painful MOM hips. The terms used to describe the findings include bursae, cystic lesions and solid masses. A recently used term, pseudotumour, incorporates all of these lesions. We aimed to correlate the pattern of abnormalities on MRI with clinical symptoms.

Patients with osteochondrodysplasia frequently require Total Hip Arthroplasty at a younger age, as a result of early degenerative disease of the hip joint. The outcome of Modular Total Hip Arthroplasty in this group of patients has been reported previously. In this retrospective study we evaluated the outcome of custom made (CADCAM) Total Hip Arthroplasty in patients with osteochondrodysplasia.

Between 1974 and 2009, twenty one CADCAM Total Hip Arthroplasty procedures were performed in fourteen patients in our institution. There were eight female and six male patients, with the mean age at time of surgery of 40.95 years (20 to 78). The patients were followed up clinically and with the Harris hip score for a mean of 7.12 years (0.5 to 17 years).

Four of the twenty-one hips (23.8%) required revision surgery at a mean of 11.54 years (6.5 to 17 years); one required it for aseptic loosening of the femoral component; one required complete revision of the acetabular component; one required exchange of acetabular liner; and one was for symptomatic non-union of a lesser trochanter avulsion.

This study shows encouraging clinical outcomes of custom made (CADCAM) Total Hip Arthroplasty in patients with osteochondrodysplasia,

Introduction

Melorheostosis is a rare bone dysplasia characterized by its classic radiographic appearance resembling dripping candle wax. The condition was originally described by Leri and Joanny in 1922. Its etiology is not fully known and treatment in most instances has been symptomatic. There are nearly 350 reported cases on melorheostosis, joint replacement has been successfully attempted in the shoulder and knee joint. We describe a case of severe melorheostosis affecting the left hip causing secondary osteo-arthritis, which was treated with a total hip replacement (THR). To the best of our knowledge this is the first reported case of its kind in the World literature.

Total hip replacements have shown great benefits to patients through relief of pain and restoration of function. However, because of the extensive variation in the size and shape of the femoral canal, especially for the situation encountered in the revision hip arthroplasty, standard uncemented hip systems with a limited number of sizes are unable to provide an accurate fit in every case. This study showed clinical results of 112 primary total hip replacements and 158 revision total hip replacements, using custom made CAD-CAM (Computer Aided Design-Computer Aided Manufactured) hip prostheses inserted between 1992 and 1998.

For primary hip replacements, the implants were designed to produce proximal line-to-line fit with the femoral bone and to provide optimal biomechanical environment of the hip. The stem was HA coated, 53 males and 58 females were included. Mean age was 46.2 years (range 24.6yrs - 62.2 yrs). The average duration of the follow up was 24 years (10 – 17 years). The mean Harris Hip Score (HHS) was improved from 42.4 to 90.3, mean Oxford Hip Score (OHS) was improved from 43.1 to 18.2 and the mean WOMAC hip score was improved from 57.0 to 11.9. There was 1 revision due to failure of the acetabular components but there were no failures of the femoral components. In the whole follow-up period, the survival of the femoral stem alone was 100%.

For revision hip replacements, the implants were designed using our design strategies of graduate approach to different revision situation based on Paprosky's classification of femoral bone defect. The implants were HA coated; some of them had distal cutting flutes. A total of 158 patients (97 males and 61 females) who had operation between 1991 and 1998 were followed up, among them 138 cases were due to aseptic loosening, 6 cases were periprosthetic fractures and 14 cases were infection. The average age was 63.1 years (range 34.6 – 85.9 years). The minimum follow up was 10 years (range 10 – 12 years). The mean Harris Hip Score was improved from 44.2 to 89.3, mean Oxford Hip Score was improved from 41.1 to 18.2 and the mean WOMAC hip score was improved from 52.4 to 12.3 respectively. 6 cases required further revision surgery, among them 3 were due to aseptic implant loosening, the overall survivorship at ten years was 97%.

The CAD-CAM hip stems are able to provide optimal implant fixation and restore hip function for every patient regardless their original femoral shape, bone condition and biomechanics of the hip. The excellent medium to long term clinical results justifies the use of CAD-CAM custom hip stems.

Summary

We report the first use of synchrotron xray spectroscopy to characterize and compare the chemical form and distribution of metals found in tissues surrounding patients with metal-on-metal hip replacements that failed with (Ultima hips) or without (current generation, large diameter hips) corrosion.

Non-invasive expandable prostheses for limb salvage tumour surgery were first used in 2002. These implants allow ongoing lengthening of the operated limb to maintain limb-length equality and function while avoiding unnecessary repeat surgeries and the phenomenon of anniversary operations.

A large series of skeletally immature patients have been treated with these implants at the two leading orthopaedic oncology centres in England (Royal National Orthopaedic Hospital, Stanmore, and Royal Orthopaedic Hospital, Birmingham).

An up to date review of these patients has been made, documenting the relevant diagnoses, sites of tumour and types of implant used. 87 patients were assessed, with an age range of 5 to 17 years and follow up range of up to 88 months.

Primary diagnosis was osteosarcoma, followed by Ewing's sarcoma. We implanted distal femoral, proximal femoral, total femoral and proximal tibial prostheses. All implants involving the knee joint used a rotating hinge knee. 6 implants reached maximum length and were revised. 8 implants had issues with lengthening but only 4 of these were identified as being due to failure of the lengthening mechanism and were revised successfully. Deep infection was limited to 5% of patients.

Overall satisfaction was high with the patients avoiding operative lengthening and tolerating the non-invasive lengthenings well. Combined with satisfactory survivorship and functional outcome, we commend its use in the immature population of long bone tumour cases.

There is very limited literature available on the use of prosthetic replacement in the treatment of primary and secondary tumours of the radius. In the past these were treated with vascularised and non-vascularised autografts which had associated donor site morbidity, problems of non union, graft or junctional fractures and delayed return to function. Our study is a mid to long term follow-up of implant survivorship and the functional outcome of metal prosthetic replacement used for primary and metastatic lesions of radius. We had 15 patients (8 males:7 females) with a mean age of 53 years. 8 patients underwent proximal radial replacement, 2 with mid-shaft radial replacement and 6 patients had distal radial replacements with wrist arthrodesis. The indications for replacement included metastatic lesions from renal cell carcinoma, primary giant cell tumours, ewings' sarcoma, chondroblastoma, radio-ulnar synostosis and benign fibrous histiocytoma. The average follow up was 5 years and 6 months (range 3 months - 18 years). Four patients died as a result of dissemination of renal cell carcinoma and two patients were lost to follow-up. There were no complications with the prosthesis or infection. Clinically and radiographically there was no loosening demonstrated at 18 years with secure fixation of implants. Two patients developed interossoeus nerve palsies which partially recovered. Functional outcomes of the elbow were assessed using the Mayo performance score with patients achieving a mean score of 85 postoperatively (range 65-95). All but one patient had full range of motion of the elbow. The patient with radio-ulnar synostosis had a 25 degree fixed flexion pot-operatively. Although the distal radial replacements had decreased range of movements of the wrist due to arthrodesis, they had excellent functional outcomes. Only one patient required revision surgery due to post-traumatic loosening of the implant. Our results of the use of endoprosthetic replacement of radius in the treatment of tumours are encouraging with regards to survivorship of the implant and functional outcome. This type of treatment results in an early return to daily routine activties, good functional outcome and patient satisfaction.

Purpose

The rate of arthroplasty or osteotomy in patients who had undergone autologous chondrocyte implantation (ACI) for osteochondral defects in the knee was determined. Furthermore, we investigated whether any radiographic evidence of osteoarthritis (OA) prior to ACI was associated with poorer outcome following surgery.

Polymethyl methacrylate spacers are commonly used during staged revision knee arthroplasty for infection. In cases with extensive bone loss and ligament instability, such spacers may not preserve limb length, joint stability and motion.

We report a retrospective case series of 19 consecutive patients using a custom-made cobalt chrome hinged spacer with antibiotic-loaded cement. The “SMILES spacer” was used at first-stage revision knee arthroplasty for chronic infection associated with a significant bone loss due to failed revision total knee replacement in 11 patients (58%), tumour endoprosthesis in four patients (21%), primary knee replacement in two patients (11%) and infected metalwork following fracture or osteotomy in a further two patients (11%). Mean follow-up was 38 months (range 24–70). In 12 (63%) patients, infection was eradicated, three patients (16%) had persistent infection and four (21%) developed further infection after initially successful second-stage surgery. Above knee amputation for persistent infection was performed in two patients.

In this particularly difficult to treat population, the SMILES spacer two-stage technique has demonstrated encouraging results and presents an attractive alternative to arthrodesis or amputation.

Introduction

We report the initial 2 and 3 year follow-up results of this randomised controlled trial of autologous chondrocyte implantation (ACI) using porcine-derived collagen membrane as a cover (ACI-C) versus matrix-carried autologous chondrocyte implantation (MACI) for the treatment of osteochondral defects of the knee.

Aims

To investigate (1) The relationship between macroscopic grading and durability of cartilage repair following collagen-covered autologous chondrocyte implantation (ACI-C) in the knee; (2) The influence of histology on durability of cartilage repair; (3) The relationship between macroscopic appearance and histology of repair tissue.

It is thought that metal ions from metal on metal bearing hip replacements cause DNA damage and immune dysfunction in the form of T cell mediated hypersensitivity. To explore the hypothesis that there is a relationship between metal ion levels and DNA damage and immune dysfunction in matched patient groups of hip resurfacings and standard hip replacements reflected in the levels of lymphocyte subtypes (CD3+ T cells, CD4+ T helper cells, CD8 +T cytotoxic/suppressor cells, CD16 +Natural Killer and CD19+ B cells) in peripheral blood samples, we analysed peripheral blood samples from 68 patients: 34 in the hip resurfacing group and 34 in the standard hip arthroplasty group. Samples were analysed for counts of each sub-group of lymphocyte and cytokine production. Whole blood cobalt and chromium ion levels were measured using inductively-coupled mass spectrometry. All hip components were well fixed.

Cobalt and chromium levels were significantly elevated in the resurfacing group compared to the hybrid group (p<0.001). There was a statistically significant decrease in the resurfacing group's level of CD8+ cells (T cytotoxic/suppressor) (p=0.010). No other subgroup of lymphocytes was significantly affected. Gamma interferon levels post antigen challenge were severely depressed in the hip resurfacing group.

A threshold level of blood cobalt and chromium ions for depression of CD8+ T cells was observed. Hip resurfacing patients have levels above this threshold whilst standard hip replacements fall below it. The patients all had normal levels of CD16 +Natural Killer and CD19+ B cells suggesting that this is not a bone marrow toxic effect. Cytokine analysis confirmed that some aspects of T cell function in hip resurfacing patients are severely depressed.

Purpose

We report on minimum 2 year follow-up results of 71 patients randomised to autologous chondrocyte implantation (ACI) using porcine-derived collagen membrane as a cover (ACI-C) and matrix-induced autologous chondrocyte implantation (MACI) for the treatment of osteochondral defects of the knee.

Introduction

The treatment of distal femoral cartilage defects using autologous chondrocyte implantation (ACI) and matrix-guided autologous chondrocyte implantation (MACI) is become increasingly common. This prospective 7-year study reviews and compares the clinical outcome of ACI and MACI.

Background

Endoprosthetic reconstruction is an established method of treatment for primary bone tumours in children. Traditionally these were implanted with cemented intramedullary fixation. Hydroxyapatite collars at the shoulder of the implant are now standard on all extremity endoprostheses, but older cases were implanted without collars. Uncemented intramedullary fixation with hydroxyapatite collars has also been used in an attempt to reduce the incidence of problems such as aseptic loosening. Currently there are various indications that dictate which method is used.