Aims

The aim of this study was to determine whether patients with metal-on-metal (MoM) arthroplasties of the hip have an increased risk of cardiac failure compared with those with alternative types of arthroplasties (non-MoM).

Objectives

The use of ceramic femoral heads in total hip arthroplasty (THA) has increased due to their proven low bearing wear characteristics. Ceramic femoral heads are also thought to reduce wear and corrosion at the head-stem junction with titanium (Ti) stems when compared with metal heads. We sought to evaluate taper damage of ceramic compared with metal heads when paired with cobalt chromium (CoCr) alloy stems in a single stem design.

Arthroplasty registries are important for the surveillance of joint replacements and the evaluation of outcome. Independent validation of registry data ensures high quality. The ability for orthopaedic implant retrieval centres to validate registry data is not known. We analysed data from the National Joint Registry for England, Wales and Northern Ireland (NJR) for primary metal-on-metal hip arthroplasties performed between 2003 and 2013. Records were linked to the London Implant Retrieval Centre (RC) for validation. A total of 67 045 procedures on the NJR and 782 revised pairs of components from the RC were included. We were able to link 476 procedures (60.9%) recorded with the RC to the NJR successfully. However, 306 procedures (39.1%) could not be linked. The outcome recorded by the NJR (as either revised, unrevised or death) for a primary procedure was incorrect in 79 linked cases (16.6%). The rate of registry-retrieval linkage and correct assignment of outcome code improved over time. The rates of error for component reference numbers on the NJR were as follows: femoral head category number 14/229 (5.0%); femoral head batch number 13/232 (5.3%); acetabular component category number 2/293 (0.7%) and acetabular component batch number 24/347 (6.5%).

Registry-retrieval linkage provided a novel means for the validation of data, particularly for component fields. This study suggests that NJR reports may underestimate rates of revision for many types of metal-on-metal hip replacement. This is topical given the increasing scope for NJR data. We recommend a system for continuous independent evaluation of the quality and validity of NJR data.

Cite this article: Bone Joint J 2015;97-B:10–18.

Introduction

Metal-on-metal (MOM) total hip arthroplasty using large diameter femoral heads offer clinical advantages however the failure rates of these hips is unacceptably high. Retrieved hips have a wide range of wear rates of their bearing and taper surfaces and there is no agreement regarding the cause of failure.

Detailed visual inspection is the first step in the forensic examination of failed hip components and may help explain the mechanisms of failure. The aim of this study was to determine if there was a correlation between the results of detailed inspections and the volumetric wear of the bearing and taper surfaces of retrieved hips.

Introduction:

There has been widespread concern regarding the adverse tissue reactions after metal-on-metal (MoM) total hip replacements (THR). Concerns have also been expressed with mechanical wear from micromotion and fretting corrosion at the head/stem taper junction in total hip replacements. In order to understand the interface mechanism a study was undertaken in order to investigate the effect of surface finish and contact area associated with modular tapers in total hip replacements with a single combination of materials of modular tapers.

Introduction

It has been suggested that corrosion and fretting at the taper junctions of stemmed metal-on-metal hip replacements may contribute to their high failure rates. A peer-reviewed semi-quantitative scoring system [Goldberg et al., 2002] has been used to visually assess the severity of corrosion and fretting of the taper junction but has not been validated using multiple examiners. The aim of this study was to assess the inter-observer variability of this method.

Introduction

Recent retrieval studies and registry reports have demonstrated an alarming incidence of early failure of metal-on-metal THR. This appears to be due to fretting and corrosion at the taper junction (trunnion) between the neck and large diameter heads in metal-on-metal hip implants. It has been proposed that designs with lower bearing clearances and greater cup flexibility deform during implantation leading to increased frictional torque and micromotion at the head-neck taper junction. Small movements at the trunnion may suggest elastic deformation, but large movements may suggest slippage at the friction interface. This study was conducted using retrieved metal-on-metal components to test the hypotheses that: 1. Cup deformation through localized compression leads to increased bearing torque, and 2. Increased torques generated in large head metal-on-metal bearings cause motion of the head-neck taper junction.

Metal-on-metal (MOM) total hip arthroplasty and hip resurfacing using large diameter femoral heads offer clinical advantages, however the failure rates of these hips are unacceptably high. Retrieved MOM hips have a wide range of wear rates of their bearing surfaces and there is ongoing research to identify the causes of failure.

Detailed visual inspection is the first step in the forensic examination of failed hip components, but there is no universally accepted description or process. Visible features may help explain the mechanism of failure of MOM hips.

During our analysis of 2000 MOM hip components, we have developed protocols to undertake detailed, non-destructive macroscopic and stereomicroscopic examinations of each component, using quantitative assessment to document the presence of types of damage.

We have established a systematic terminology to describe the types of damage that are observed, allowing for consistency and clarity in the vocabulary used. These include (but are not limited to):

Scratching – when there is an increase in the number and/or magnitude of scratches present on the surface, typically increasing measured roughness parameters. The severity of scratching is determined by rubbing a 0.18 mm thickness acetate gage or fingernail over the surface:

Light –visible but not detectable with gage.

To assess the distribution of these types of damage on the components, each surface is considered in terms of zones defined by quadrants (cup, head, stem and taper) and sub-quadrants (cup and head only), Figure 1. Each zone is scored on a scale of 0 to 3 by determining the percentage of the surface area of the quadrant that exhibits the feature in question:

a score of 0 indicates 0% 1

indicates greater than 0% but less than 25%

The use of zones to differentiate between the polar and equatorial regions of the cup and head surfaces can offer important information relating to the articulation of the bearing surfaces. For example in a cohort of 90 inspections, a score of 3 for light scratching was recorded in all areas of the bearing surface in 40% of cups, whilst approximately 5% had evidence of pitting, occurring near the rim.

Current research at our retrieval centre involves correlating the results of detailed inspections with a range of variables, including implant design, size and surgical position.

We present the medium to long term clinical results of 112 Uncemented custom Computer Assisted Design Computer Assisted Manufactured (CAD-CAM) total hip arthroplasties performed between 1992 and 1998 in 111 patients. Fifty three males and 58 females were included. Mean age was 46.2 years (range 24.6yrs - 62.2 yrs). Average duration of follow up was 156 months (120 – 204 months). The mean Harris Hip Score (HHS) improved from 42.4 to 90.3, mean Oxford Hip Score (OHS) improved from 43.1 to 18.2 and the mean WOMAC hip score 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. There were no revisions for aseptic loosening. The worst case survival in this cohort of custom femoral components at an average 13 year follow up (range 10-17 years) was 98.2% (95% Confidence interval 95% to 99%). Survival of the femoral component alone was 100%.

These results are comparable with the best medium to long term results for femoral components used in primary total hip arthroplasty (THA) with any means of fixation.

Introduction: Within a study group of 102 consecutive patients diagnosed with chondrosarcoma of the femur, tibia or humerus, an association with previously treated breast cancer was noted. We researched this proposed relationship.

Methods: We retrospectively reviewed the records of all patients diagnosed histologically with chondrosarcoma of the femur, tibia or humerus over a six-year period at a supra-regional bone tumour unit. We identified those patients who had previously been treated for breast cancer.

Results: There were 58 female and 44 male patients. The study group contained six females (10%, mean age 53 years) who had previously been treated for breast cancer, a higher proportion than would be expected. They were referred following identification of a solitary area of increased activity on routine screening with isotope bone scan, presumed to be a solitary bony metastasis. Most (86%) of this breast carcinoma sub-group had developed low-grade bone chondrosarcoma (Trojani grade 0.5-I) and only one case (14%) had developed high-grade chondrosarcoma (Trojani grade II–III).

Discussion: A suspicious long bone lesion on bone scan in a patient with a past medical history of breast cancer must, therefore, not be assumed to be a metastasis without further investigation; the possibility of a chondral lesion should be considered. It is important that patients receive a full multidisciplinary team investigation prior to treatment in order to obtain the correct tissue diagnosis, as the management of these conditions is often different. Our study suggests there may be a relationship between patients previously treated for breast cancer and the development of subsequent chondrosarcoma.

Introduction: Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue neoplasm most commonly presenting in young to middle-aged adults. LGFMS is an indolent tumour with a deceptively benign histological appearance. Local recurrences are not uncommon and tumours can metastasise. The FUS-CREB3L2 gene translocation has been shown to occur commonly in cases of LGFMS. The literature suggests that the FUS-CREB3L2 fusion-gene is a specific marker for LGFMS.

Methods: We report the cytogenetic analysis of 29 LGFMS cases, and clinical outcomes of 21 patients treated surgically between 1998 and 2008 at our regional bone and soft-tissue tumour centre.

Results: The mean age was 45.4 years and mean follow-up 30.1 months. The most common tumour location was the lower limb. There were no cases of local recurrence or metastasis. Fifteen patients (52.2%) were FUS-CREB3L2 translocation-positive, suggesting either that translocation incidence in our series is lower than other studies, or that reverse-transcriptase polymerase chain reaction (PCR) is less sensitive than the literature suggests. Patients testing positive presented at a younger age (38.2 years, compared to 45.6 years), and had larger tumours than their negative counterparts (mean diameter 97.6mm, compared to 65.2mm), although there was no difference in clinical outcome.

Discussion: We conclude that PCR testing for the FUS-CREB3L2 translocation is a useful tool for confirming the diagnosis of LGFMS, but has no role in predicting short-term clinical outcome. It is not necessary to perform wide excision, and marginal margins are adequate. Longer-term follow-up is required to elucidate differences in the long-term clinical outcome between translocation-positive and negative patients.

Introduction: Intramedullary cementless fixation of massive tumor prostheses was developed to combat the high incidence of aseptic loosening in a young population of tumor patients. Its use has also expanded to include reconstruction of failed major knee arthroplasty. Our system uses a hydroxyapatite coated titanium stem in conjunction with a hydroxyapatite collar to obtain fixation.

Methods: We present a series of 72 patients (34 females, 38 males) with a mean follow-up of six years (2 months – 14 years). The mean age at the time of surgery was 17 (5 – 77). Within this group, 51 patients had osteosarcomas, 10 had giant cell tumors, eight had Ewing’s sarcoma and one each had malignant fibrous histiocytoma, spindle cell sarcoma and failed total knee arthroplasty. Non-invasive and minimally invasive growing prostheses were used in 33 patients.

Results: Nine patients required revision of the prosthesis at a mean of 5.2 years; 5 for aseptic loosening and four for infection. Twelve patients died at a mean of 20 months (1 – 84) post-operatively. Radiological evidence demonstrated remodelling around both the stem and the collar. There was gap closure to the hydroxyapatite coated collar in cases where seating was not complete. Consistent loss of cortical bone around the mid-stem was noted in the first 12 months but remained stable beyond this time frame.

Discussion: This study highlights our experience with cementless distal femoral endosprostheses. We demonstrate good results with regard to revision rate, gap closure and osseointegration.

Introduction: Chondrosarcoma is the second most common primary malignant bone tumour. Distinguishing between grades is not necessarily straightforward and may alter the management of the disease. We evaluated the correlation between the pre-operative needle biopsy and excision biopsy histological grading of chondrosarcoma of the femur, tibia and humerus.

Methods: A consecutive retrospective series of 100 patients with a histological diagnosis of chondrosarcoma made at a supra-regional bone tumour unit was reviewed. Twenty-one patients were excluded because 20 had only excision biopsy, due to radiological confidence in the diagnosis, and one had only the pre-operative biopsy on record, thus this series included 79 available cases. The remaining patients underwent a pre-operative needle biopsy.

Results: In 11 instances, there was a discrepancy in histological grade. Therefore, there was an 86% (68 out of 79) accuracy rate for pre-operative histological grading of chondrosarcoma, based on needle biopsy. However, the accuracy of the diagnostic biopsy to distinguish low-grade from high-grade was 90% (71 out of 79).

Discussion: From this series we conclude that accurate image-guided biopsy is a very useful adjunct in determining histological grade of chondrosarcoma and the subsequent treatment plan. At present, a multidisciplinary approach, comprising experienced Orthopaedic Surgeons, Radiologists and Pathologists offers the most reliable means of accurately diagnosing and grading chondrosarcoma of long bones.

Introduction: Alveolar soft part sarcoma (ASPS) is a soft tissue tumour found primarily in adolescents and young adults. It has an incidence of 0.5 – 1.0 % of all soft tissue sarcomas and a predilection for females. The lesion is inherently malignant and may occur throughout the body however, reports suggest they are predominantly detected in the anterior thigh. Symptoms include a painless slow-growing mass but ASPS can commonly present with brain or lung metastases due to the high vascularity of the lesion. Microscopically, cellular groups exist with centralised areas of necrosis, thus resulting in a pseudoalveolar appearance.

Methods: We identified six cases of histologically proven ASPS. The mean age was 28.5 years (21–36). Four patients were male. All patients had a primary presentation of a mass, two of which were painful. All patients, except one, presented within 8 months of the onset of symptoms (mean 3.8 months) with the other seeking medical advice only after 72 months. The location of the mass included the thigh in three patients and the triceps, soleus and retroperitoneal space in the others. Four patients underwent pre-operative diagnostic biopsies. Surgical excision was performed in all patients.

Results: The mean size of tumour was 9.4 x 9.4 x 6.3cm but there was no correlation between lesion size and duration of symptoms. The patient who presented late was found to have multiple lung metastases prior to surgery. Despite appropriate adjuvant therapy, three patients developed post-operative metastases at a mean of 5.2 months (1–24), two of which died along with the patient who presented with metastases at a mean of 2.6 years.

Discussion: This series demonstrates that this tumour may present as a painful mass. Despite early detection and appropriate treatment, ASPS remains a highly malignant neoplasm with a high associated mortality rate.

Data on retrieval analysis of current generation metal on metal hip replacements is scarce. Such analysis may help to reduce the incidence of failure and revision procedures. Our aim was to investigate the wear characteristics of explanted (ie failed) metal on metal (MOM) acetabular components in terms of; 1) wear rate; and 2) distribution of the wear (specifically edge loading).

30 hips were collected from 20 centres. The types of prostheses were: 15 BHR; 10 Cormet and 5 ASR. Wear of the acetabular components of the prostheses was measured using an out of roundness (Rondcom 60A) machine. We recorded the implantation and removal date of each hip.

The median linear wear rate was 7.32μm/year; this is at least 3 times greater than steady state wear rates reported for similar components worn in hip simulator studies. For 24 out of 30 cups, the greatest linear wear was recorded at the cup edge.

Failed metal-on-metal acetabular components were associated with higher than expected wear rates. The highest wear was seen closest to the cup edge in the majority of patients suggesting edge loading had occurred and probably explained the high wear rates. Accurate cup placement (to avoid edge loading) may reduce the failure of MOM hips.

Aims: he purpose of this study was to determine whether autologous chondrocyte implantation (ACI) in patients with articular cartilage defects of the knee resulted in patients returning to pre-injury levels of work and physical activities.

Methods: 133 consecutive patients from January 2001 to December 2002 underwent ACI at our institution. A telephone and postal questionnaire was conducted to ascertain a detailed occupational and leisure activity profile in this cohort of patients. For each job held for at least 2 months, we asked whether an average working day had involved any of the ten specified physical activities. Similarly, for each sport that had been played more than 5 times a year, we asked the age the sporting activities had began and whether they were able to return to these sports after surgery. Occupation for each patient was given a 3 digit code according to the Standard Occupational Classification System 2000 and hence determined whether the work performed was manual or non-manual.

Results: 97 patients responded to the questionnaire. There were 53 females and 44 males and the mean age at the time of operation was 34.5 (range 14 to 49). Category 6 (Personal Services Occupations) was the most common occupation pre-operatively, whereas category 4 (Administrative and Secretarial Occupations) was the most common post-operatively. 7% of patients’ work involved kneeling or squatting and this figure rose to 12%, 4 years following surgery. 42% of patients had to make some form of modification to their work (usually less physical or more office based). 47% of patients were able to return to at least one of the sports they played pre-injury.

Conclusion: This is the first study to demonstrate that patients are able to return to work and resume sporting activity following autologous chondrocyte implantation.

Background: Advances in adjuvant and neoadjuvant therapies have rendered many tumours that previously necessitated amputation amenable to limb salvage procedures. However, a significant proportion of tumours are still treated by hindquarter amputation in an attempt to cure the patient, or to reduce the tumour load. This tends to be lengthy, mutilating and is associated with high morbidity and poor survivorship.

Aims: To review the survivorship, quality of life and functional assessment following hindquarter amputations performed in this centre in the last 10 years.

Methods: This was a retrospective study of 51 consecutive patients who had hindquarter amputations for tumours between 1996 to 2006. Available patients were evaluated using contemporary functional outcome assessments (Musculoskeletal Society Tumour Score, Toronto Extremity Salvage Score, SF36).

Results: Fifty-one patients (31 males, 20 females) had palliative(8) or curative hindquarter amputations(43) for Chondrosarcoma(18), Malignant Fibrous Histiocytoma(6), Osteosarcoma(4) and other sarcoma sub-types(23). The mean age was 50.7 years (range 24–78). The mean duration of symptoms until referral was 5.2 months, the mean time from referral to tissue diagnosis was 16.2 days (range 2–80) and the time from confirmed histological diagnosis to surgery was 39.2 days (range 2–190) on average. Significant complications included phantom limb pain(15), wound problems(24), urinary problems(6), cardiopulmonary events(5) and erectile dysfunction(3). 33 of the 51 patients have passed away, with a mean survival postoperatively of 10.7 months (range 2–43), with carcinomatosis the main cause of death. The mean cumulative survival following hindquarter amputation in this hospital is 17.3 months.

Conclusions: Patients with no metastasis and clear margins at amputation had a better cumulative survival rate. Therefore the decision to proceed for hindquarter amputation to achieve a curative resection is justified but has to be weighed up against the associated significant complications, morbidity and functional deterioration.

Introduction and aim: Several authors have suggested that hyaline repair tissue following autologous – chondrocyte implantation (ACI) gives better clinical results than either mixed hyaline and fibrocartilage or fibrocartilage alone. This data is based on the use of periosteum as a covering membrane in these previous studies. We have for some years been using a porcine collagen type 1/III membrane (ACI-C) instead of periosteum and have now the opportunity to analyze the clinical results when compared with the histology of the repaired defect. We have also analysed the influence on the result of age and sex of the patient, the etiology of the lesion, the duration of the knee symptoms, number of previous knee procedures, the site and size of defect and the preoperative functional scores.

Method: Until 2004, 234 patients underwent autologous chondrocyte implantation at our centre. The patients were assessed clinically by their modified Cincinnati scores prospectively from 1 to 4 years from surgery. Also at arthroscopy (1 to 3 years following ACI-C) they underwent biopsy of the implant where possible and the neo-cartilage was graded as hyaline (H), mixed fibrohyaline (F.H), fibrocartilagenous (F.C) and fibrous (F).

Results: The clinical results showed that older patients had poorer results (p< 0.001) and a high preoperative modified Cincinnati score predicted a good result (p< 0.001). Concerning the cause of the defect, the percentage of patients with excellent and good results were significantly low among those with previously failed ACIs and mosaicplaties (12.5%) compared with those following trauma, osteochondritis dessicans and chondromalacia patellae (67% to 77%). At 4 year follow-up, 75% of patients with hyaline neo-cartilage had excellent and good modified Cincinnati scores whereas those with mixed fibro-hyaline and fibro-cartilage had fewer excellent and good results (44.4% and 54.5% respectively). The other parameters such as gender, the site of defect, duration of knee symptoms and the number of previous procedures and the size of the defect did not significantly influence the outcome. In conclusion, patients most likely to benefit from autologous chondrocyte implantation using a collagen membrane (ACI – C) are younger patients with higher preoperative functional scores and those who develop hyaline neo-cartilage.