A 66-year-old man presented with an infected resurfacing hip replacement in the immediate post-operative period following an uneventful transurethral resection of the prostate. Prophylactic antibiotics had been administered on induction of anaesthesia. The hip prosthesis had been inserted seven years previously and had been hitherto asymptomatic. The hip was washed out and microbiological examination identified Enterococcus faecalis as the infecting micro-organism. Despite current recommendations, clinicians undertaking invasive procedures which can lead to bacteraemia in patients with prosthetic joint replacements should be aware of the risk of haematogenous seeding in such prostheses, which although low, has potentially disastrous consequences

Introduction: Peri-prosthetic fractures following hip resurfacing arthroplasty are difficult fractures to treat. The surgeon is faced with the task of either attempting to fix the fracture if feasible or revise the resurfacing implant to a conventional total hip replacement. Method & Results: Here we report of a novel way of fixing a peri-prosthetic fracture following resurfacing hip arthroplasty using Polyaxial locking plate fixation. A 53 year old man sustained a intertrochanteric fracture below his resurfacing metal on metal hip prosthesis following a fall. He had his hip resurfaced 3 years back for osteoarthritis in another hospital. He underwent surgery to fix the fracture using a polyaxial locking plate with no post-operative complications. He was mobilised non-weight bearing for the initial six weeks and weight bearing as tolerated thereafter. He went on to union and was moblising without any problems in three months time. His follow-up x-rays at 8 months showed fracture healed with no evidence of prosthesis problems. Discussion: There are various methods of treating a periprosthetic fracture of a well fixed resurfaced hip implant. The two types of management are open reduction and internal fixation and revision to a stemmed hip implant. These fractures can be fixed with cannulated hip screws, blade plate device or plating with screws avoiding the stem of the resurfacing prosthesis. We used the polyaxial locking plate device with good result thereby avoiding the need for revision surgery with its attendant risks. Using this implant is a useful alternative for these fracture patterns

Introduction: Femoral neck failure due to avascular necrosis (AVN) is one of the most significant complications following resurfacing hip arthroplasty. It is likely that the surgical approach is one of the factors influenc-ing the development of AVN. Positron emission tomography (PET) is the only form of imaging that allows visualisation of bone metabolic activity deep to a metal surface. Objectives: To establish the reliability and accuracy of PET using fluorine-18 to evaluate viability of the femoral head and neck after resurfacing hip arthroplasty. To assess the viability of ten proximal femora after Birmingham resurfacing hip arthroplasty via a modified lateral approach. Design: A convenience case series of ten patients taken from the first fifteen from one orthopaedic surgeon’s experience of Birmingham resurfacing hip arthroplasty. Setting: The PET unit of a major urban teaching hospital with a large academic orthopaedic department. Participants: Patients that had undergone unilateral Birmingham resurfacing hip arthroplasty via a modified lateral approach were asked to volunteer for the study. The main criterion for inclusion was ease of attendance for imaging. Intervention: Participants were given a single intravenous dose of 250MBq fluorine-18. After a period of 40 minutes uptake time, PET images of adjacent, sequential 10cm transverse sections including both acetabulae and proximal femora were obtained. Main Outcome Measures: Images were reconstructed to allow relative quantification of uptake between operated and non-operated femoral heads and necks. Results: PET imaging was successful in all subjects and demonstrated activity within the resurfaced femoral heads and femoral necks. No evidence of AVN was found. Conclusions: Static positron emission tomography using fluorine-18 is an accurate and reliable method of assessing femoral head and neck viability after resurfacing hip arthroplasty. No evidence of avascular necrosis was found in this initial series of patients that had undergone Birmingham resurfacing hip arthroplasty via a modified lateral approach

Correct positioning of the femoral component in resurfacing hip arthroplasty (RHA) is an important factor in successful long-term patient outcomes. Computer-assisted navigation (CAS) shows potential to improve implant positioning and possibly prolong survivorship in total hip and knee arthroplasty. The purposes of CAS systems in resurfacing the femoral head are to insert the femoral head and neck guide wire with greater accuracy and to help in sizing the femoral component, thus reducing the risk of notching of the head and neck junction. Several recent studies reported satisfactory precision and accuracy of CAS in RHA. However, there is little evidence that computer navigation is useful in the presence of anatomical deformities of the proximal femur, which is frequently observed in young patients with secondary degenerative joint disease. The purpose of this in-vitro study was to determine the accuracy of an image-free resurfacing hip arthroplasty navigation system in the presence of two femoral deformities: pistol grip deformity of the head and femoral neck junction and slipped upper femoral epiphysis deformity. An artificial phantom leg with a simulated hip and knee joint was constructed from machined aluminum. Implant-shaft angles for the guide wire of the femoral component reamer were calculated, in frontal and lateral planes, with both a computer navigation system and an electronic caliper combined with micro-CT. With normal anatomy we found close agreement between the CAS system and our measurement system. However, there was a consistent disagreement in both the frontal and lateral planes for the pistol grip deformity. Close agreement was found only on the frontal plane angle calculation in the presence of the slipped upper femoral epiphysis deformity, but calculation of the femoral head size was inaccurate. This is the first study designed to assess the accuracy of a femoral navigation system for resurfacing hip arthroplasty in the presence of severe anatomical deformity of the proximal femur. Our data suggests CAS technology should not be used to expand the range of utilisation of resurfacing surgery, but rather to improve the surgical outcome in those with suitable anatomy

Aims: To compare the results of resurfacing hip arthroplasty with conventional total hip replacement and to find out any differences in complication rates, discharge patterns and the resulting financial implications. Trial Design: Retrospective analysis comparing resurfacing hip arthroplasties to conventional total hip replacements in patients who were 65 years old or younger at the time of operation. Criteria for comparison were blood loss, post operative complications (including the need for blood transfusion), revision of arthroplasty and the length of hospital stay. Materials and Methods: All patients who had resurfacing arthroplasty in our hospital were included in the study (77 patients), and a similar group who had total hip replacements in the same time period were randomly selected for comparison. Case notes, computer records as well as X-rays were used to identify postoperative complications, especially DVT’s ,PE’s, neuro-vascular injuries, infection, fractured neck of femur and the need for revision of an arthroplasty. A detailed analysis of all revision arthroplasties including the causes, failure pattern of implant and the type of revision hip arthroplasty used and its cost implication was made. We also compared the pre and post-operative haemoglobin and units of blood transfused, if any. A comparison was also made of discharge pattern of these two groups of patients. A student t-test was performed to observe any difference in these two group. Results:. Resurface hip arthroplasty Group: Average age 52.1 years; pre-operative Hb 14.22gm/dl; postoperative Hb.10.95gm/dl; average blood loss 3.28 gm/dl; Total hips revised 12; Average length of stay 8.53 days. Total hip arthroplasty Group: Average age 58.8 years; pre-operative Hb 13.97gm/dl; post-operative Hb 10.65m/dl; average blood loss 3.5 gm/dl; Total hips revised 0; Average length of stay 8.9 days. Conclusions: 1.There were no appreciable differences between these two group as far as the usual complications, blood loss and length of stay are concerned. 2. There was appreciable difference in revision rate, which has significant cost implication for health authority and patients

Introduction: The Resurfacing Hip has been increasingly popular for younger patients. Femoral neck fractures are still the main complication. The problems associated with cement such as thermal necrosis, cement debris and lack of long-term biological fixation, combined with the general use of cementless fixation in young patients invite the question whether a cementless component can be used for resurfacing hip replacement. Given that the cement may reinforce the femoral head preventing collapse, an additional question regarding the effect of bone density in cemented and cementless fixation can be asked. The hypotheses of the study are that:. High bone density will increase the yield point and stiffness of the femoral head and therefore improve the implant fixation. Cement fixation will increase the yield point and stiffness of the femoral head, especially for the lower density bone compared with cementless fixation. Materials and Methods: Thirty-six femoral head specimens were obtained from consented patients receiving routine hip arthroplasty. The heads were stored frozen at −20oC until use. pQCT was used to analyse trabecular bone density within each head. Specimens were ranked according to bone density and were assigned to high and low bone density groups. Cemented and cementless fixations were then alternatively assigned to individual heads in each group. Thus the 4 groups included in the study were: High density cemented, high density cementless, low density cemented, and low density cementless. Implantation of Birmingham resurfacing hips was carried out according to recommended surgical procedures. For cementing groups, surgical simplex P bone cement was used. Each sample was potted in a cylindrical polyethylene block for testing. A compressive load up to 5 or 10 KN using a Hounsfield Universal Testing Machine were applied on each sample at a rate of 1 mm min-1. Load versus displacement graphs were plotted for all tests. Yield point and stiffness were measured for each sample. Results:. For yield point, there is no significant difference between cemented or cementless resurfacing (4169 ± 1420 N vs. 3789 ± 1461 N; P = 0.434). However, the high density heads provide a significantly higher yield point than low density heads (4749 ± 1145 N vs. 3208 ± 1287 N; P = 0.01). The addition of cement significantly contributes to femoral head stiffness compared to cementless resurfacing (5174 ± 1730 N/mm vs. 3678 ± 1630 N/mm; P = 0.012). Discussion: Bone density plays an important role in resurfacing hip arthroplasty. Higher bone density will reduce the incidence of fractures comparing with lower density. Therefore, resurfacing THR for the older patients and those with sub-optimal bone density should be used with caution. Consequently, it is suggested that a bone density scan should be routinely applied for those patients who are considered for resurfacing hip replacement. There is no difference between the cemented and cementless fixation in reducing femoral head failure, though cement will increase the stiffness of the bone. The study suggests that cementless resurfacing hip could be an alternative design with its clinical advantages of long-term osseointegration if implant is coated with bio-active materials

We examined the relationships between the serum levels of chromium and cobalt ions and the inclination angle of the acetabular component and the level of activity in 214 patients implanted with a metal-on-metal resurfacing hip replacement. Each patient had a single resurfacing and no other metal in their body. All serum measurements were performed at a minimum of one year after operation. The inclination of the acetabular component was considered to be steep if the abduction angle was greater than 55°. There were significantly higher levels of metal ions in patients with steeply-inclined components (p = 0.002 for chromium, p = 0.003 for cobalt), but no correlation was found between the level of activity and the concentration of metal ions. A highly significant (p < 0.001) correlation with the arc of cover was found. Arcs of cover of less than 10 mm were correlated with a greater risk of high concentrations of serum metal ions. The arc of coverage was also related to the design of the component and to size as well as to the abduction angle of the acetabular component. Steeply-inclined acetabular components, with abduction angles greater than 55°, combined with a small size of component are likely to give rise to higher serum levels of cobalt and chromium ions. This is probably due to a greater risk of edge-loading

Background. Hip arthroscopy is well established as a diagnostic and therapeutic tool in the native hip joint. However, its application in the symptomatic post-hip arthroplasty patient is still being explored. Aims and Methods. We have described the use of hip arthroscopy in symptomatic patients following total hip replacement, resurfacing hip arthroplasty and partial resurfacing hip arthroplasty in 24 patients (study group), and compared it with arthroscopy of the native hip of 24 patients. Results. The diagnostic yield of hip arthroscopy in symptomatic post-arthroplasty patients was 95.8% (23 / 24) and a therapeutic arthroscopic intervention resulted in relief of symptoms in 41.6% (10 / 24) of the patients. It led to revision hip replacement in a further 29.1% (7 / 24). In contrast, hip arthroscopy of the native hip (control group) had a 100% diagnostic yield and an arthroscopic therapeutic intervention was carried out in all the patients resulting in symptomatic relief in 87.5% (21 / 24). The mean operative time in the study group (59.7 mins, SD 21.1) was less than the control group (71 mins, SD 17.1, p < 0.05) but the arthroscopic approach was more difficult. Conclusion. The authors suggest the use of hip arthroscopy in well-investigated symptomatic post-arthroplasty patients with an elusive diagnosis (Fig. 1: Arthroscopic image showing a THR in situ (Furlong, JRI, London, UK) with a ceramic femoral head (yellow arrow), ceramic acetabular liner (white arrow), florid metallosis (red arrow) and corrosion on the femoral neck (green arrow) because of impingement against the margin of the acetabular component.) and also describe the technical modifications necessary with various types of hip arthroplasty

Analysis of the different phases of the gait cycle has been shown to demonstrate differences in pathological osteoarthritic gait. These differences can be quantified and their improvement following total hip arthroplasty has been shown, allowing use of gait analysis as a tool in evaluating function after total hip replacements. The purpose of this study was to determine the degree of improvement in gait attained after resurfacing hip arthroplasty. Ten patients with monoarthritic hips were evaluated using gait analysis preoperatively and 1 year postoperatively. The results indicate that there is a significant improvement in the patients gait during the first postoperative year following resurfacing arthroplasty. There is a 30% increase in the Harris Hip score, 100% increase in the velocity of walking. 51% increase in stride length, 30% improvement in the ground reaction force and 33% improvement in cadence at 1 year. These improvements in gait mirror those shown previously following Total hip arthroplasty and show that following resurfacing procedures gait parameters are comparable to able-bodied controls. We have concluded that resurfacing hip arthroplasty can greatly improve the gait characteristics of patients with unilateral degenerative hip arthritis

Aim: The purpose of the study was to compare the position of the femoral guide wire for during hip resurfacing, computer navigation and an alignment device. Materials and Methods: 26 cadaver specimens divided in 3 randomly selected groups and 25 patients were used to evaluate the position of the femoral guide wire in resurfacing hip arthroplasty. In two groups of cadavers the Computer Navigation was used to register and template the position of the implant. The position of the guide wire was compared to the one achieved using the alignment device. In the third group of cadaver specimens only the alignment device was used to implant the guide wire. Version was determined from the transversely cut sections of the cadaver specimens. Pre operative and post operative radiographs were used for analysis. In the patient group after registration and templating the guide wire was passed using the alignment device. Results: There was no notching of the superior femoral neck in either of the groups. The mean and standard deviation of the anatomic neck-shaft angles was 124.91? ? 14.25?. The wire-shaft angle in the Navigation group was 131.46? ? 5.27? and in the alignment device group 134.08? ? 3.80?. In the navigation group the wire was in 0.85? ? 2.15? of retroversion as compared to 1.38? ? 4.19? of anteversion in Jig group. The position of the wires at the narrowest cross section of the femoral neck is shown in figure. The wire shaft angle as per navigation was 134.44(±5.55) as compared to 134.74 (±5.11). Conclusion: The alignment device consistently positioned the wire more valgus and anteverted than Computer aided navigation. In all cases, the wire position was well within acceptable limits. Computer aided navigation does not seem to offer distinct advantages in resurfacing hip replacements

Aims: To determine the pathological changes in the femur following resurfacing hip arthroplasty and identify possible causes of early failure. Methods: Bone samples from 8 femoral heads at several levels were examined histologically following removal of cemented femoral head surface replacement following aseptic early failure: 4 neck fractures (no history of fall), 3 persistent severe pain and 1 cup loosening. Intra-operatively no obvious macroscopic causes of failure (including notching the neck) were noted. In all patients, the initial diagnosis had been osteoarthritis. None had known risk factors for osteonecrosis. Results: In the patients who had recent fracture, the bony changes were suggestive of relatively longstanding osteonecrosis with degenerative, necrotic and þbrotic changes in the bone marrow and loss of osteocyte nuclei in the trabeculae. There was appositional new bone formation at the surface of the necrotic bone trabeculae. The changes were consistent with osteonecrosis of more than 2 weeks duration and probably preceded the fracture in all cases. In the patients who underwent revision for non-fracture, some osteonecrosis was seen, but this was a lot less than when a fracture had occurred. Conclusion: Osteonecrosis of the femoral head is seen following resurfacing hip arthroplasty and may be a predisposing factor in patients who subsequently fracture

Background: Resurfacing hip replacement is becoming increasingly used surgical option for young active patients with disabling hip arthritis.However there is a paucity of published literature describing complications and their avoidance. Objective The objective of this study was to analyse 6 cases of postoperative subcapital fracture following hip resurfacing with a cohort of 54 cases that did not have a fracture and to identify factors associated with fractures risk. Materials and Methods Between January 1999 and October 2003, 60 hips in 54 patients were treated with metal on metal resurfacing hip replacement (MMT Birmingham, UK).6 of these sustained a fracture just below the femoral component.The notes and radiographs were reviewed.Demographics data was recorded along with height, weight,smoking habits and medication usage including NSAIDS and antiepileptic use.The radiographs were studied for notching of the neck,offset difference as compared to normal and the stem shaft angle. The results were statistically analysed to determine any significant associations. Results 57 hips in 51 patients were analysed for comparison. The mean age of the patients was 50 yrs (Range 34–67).In the fracture cases there were three men and three women with a mean age of 48 yrs.Five of six ( 83%) in the fracture cases had notching of the femoral necks compared to 9 (17%) out of 51 of the non fractured patients. The offset was significantly greater in the fractured group(52 ± 7mm) compared to the non fractured group (49 ± 7 mm).The increase in offset appeared to occur as a result of incomplete seating of tight fitting cemented femoral component. The head size appeared smaller in the fractured group but the difference was insignificant. There was no significant trauma in any of the cases. None of the patients who underwent resurfacing for AVN and cyst had a fracture. There were no other significant correlations. Conclusions Increased offset and notching are factors which predispose to fractures following resurfacing hip replacements. AVN and cysts were not associated with fractures in our series. We have changed the cementing technique using smaller volumes of freshly mixed simplex cement and now encourage protected weight bearing if intraoperative notching is noted or if osteoporosis is identified pre or peri operatively. We have had no fractures in the last 18 months

Introduction and Aims: The use of resurfacing hip replacements has increased dramatically in recent years. The aim of this study was to compare the early results of this treatment with conventional cemented, cementless and hybrid primary total hip replacement in Australia. Method: The data used for this report included all conventional primary total hip and resurfacing procedures, as well as any subsequent revisions of those procedures which had been undertaken and reported to the Australian Orthopaedic Association National Joint Replacement Registry (AOA NJRR) before 31 December 2002. Analysis included the determination of demographics, components used and method of fixation. Early revision rates and reasons for failure were also assessed. The AOA NJRR commenced data collection in September 1999 and has had national coverage since 2002, therefore any results reported at this stage are early outcomes. Results: Almost 33,000 primary total hip replacements were recorded, of these 2130 were resurfacing procedures (6.5%). This proportion of resurfacing was consistent across states with the exceptions of Victoria (11%) and Tasmania (0.6%). Cementless hip replacement was the most common form of primary total hip replacement (41%) with hybrid (34%) and cemented (18.2 %) less common. There was marked state variation in the proportion of cemented and cementless fixation with NSW having a low proportion of cement fixation (4.5%). Early revision rates for cemented conventional primary total hip replacement are significantly less compared to cementless and hybrid hips (cemented v cementless) hazard ratio (adjusted for age and sex) 2.13; 95% CI (1.49, 3.05) p< 0.0001) (cemented v hybrid) hazard ratio (adjusted for age and sex) 1.94; 95% CI (1.37, 2.77) p=0.0002). There was no difference between cementless and hybrid hips. The most common reason for early revision was dislocation and the risk of this was related to head size with larger sizes showing a reduced risk. Although revisions per 100 observed component years were higher for resurfacing hip replacements than for conventional hips (1.73 v 1.18), this difference was not statistically significant. The principal reason for early failure of resurfacing hips was fracture. Conclusion: The AOA NJRR has identified prosthesis specific differences in early outcomes and failure mechanisms following primary total hip replacement. Continued monitoring of existing and new prostheses will provide surgeons with independent quality information to assist in the selection of the most appropriate prostheses for particular clinical situations

Seven psoas bursae filled with purulent fluid and inspissated debris were revealed at revision operations for failed resurfacing hip arthroplasties, an incidence of 5.8% in such revisions. Histological and microbiological investigations demonstrated that the psoas bursa collections resulted from the tissue response to polyethylene wear debris. None was due to infection

We report the outcome of total hip replacement in 29 failed metal-on-metal resurfacing hip replacements in which the primary surgery was performed between August 1995 and February 2005. The mean length of follow-up was five years (1.7 to 11.7). Of the 29 hip resurfacings, 19 acetabular components and all the femoral components were revised (28 uncemented stems and one cemented stem). There were no deaths and none of the patients was lost to follow-up. None of the hips underwent any further revision. The results of the revision resurfacing group were compared with those of a control group of age-matched patients. In the latter group there were 236 primary total hip replacements and 523 resurfacings performed during the same period by the same surgeons. The outcome of the revision resurfacing group was comparable with that of the stemmed primary hip replacement group but was less good than that of the primary hip resurfacing group. Long-term follow-up is advocated to monitor the outcome of these cases

Aims

This study evaluates the association between consultant and hospital volume and the risk of re-revision and 90-day mortality following first-time revision of primary hip arthroplasty for aseptic loosening.

Background. Since the development of modern total hip replacement (THR) more than 50 years ago, thousands of devices have been developed in attempt to improve patient outcomes and prolong implant survival. Modern THR devices are often broadly classified according to their method of fixation; cemented, uncemented or hybrid (typically an uncemented acetabular component with a cemented stem). Due to early failures of THR in young active patients, the concept of hip resurfacing was revisited in the 1990's and numerous prostheses were developed to serve this patient cohort, some with excellent clinical results. Experience with metal-on-metal (MoM) bearing related issues particularly involving the ASR (DePuy Synthes, Warsaw, Indiana) precipitated a fall in the use of hip resurfacing (HR) prostheses in Australia from a peak of 30.2% in 2004 to 4.3% in 2015. The effects of poorly performing prostheses and what is now recognised as suboptimal patient selection are reflected in the AOANJRR cumulative percent revision (CPR) data which demonstrates 13.2% revision at 15 years for all resurfacing hip replacements combined; with 11 different types of hip resurfacing prostheses recorded for patients less than 55 years of age and a primary diagnosis of OA. When this data is restricted to only those prostheses currently used in Australia (BHR; Smith and Nephew, Birmingham, UK & ADEPT; MatOrtho Ltd, Surrey, UK) there is a CPR of 9.5% at 15 years for all patients. Despite these CPR results, recognition is emerging of the important distinction between MoM THR and resurfacing. Furthermore, in light of current consensus for patient selection and the surgical indications for resurfacing, a gender analysis demonstrates a CPR for females of 14.5% at 10 years compared to 3.7% for males. Similar difference for head size >50mm with 6% CPR at 10 years compared to 17.6% for head size <50mm (HR=2.15; 1.76, 2.63; p<0.001). Leading to renewed interest in resurfacing particularly in the young, active male. In addition to registry based CPR data, several studies have concluded that a true difference in mortality rates between HR and other forms of THR exists independent of age, sex or other confounding factors. We hypothesised that a difference in adjusted mortality rates between HR and other forms of THR may also be present in the Australian population. We undertook an ad hoc data report request to the AOANJRR. The data set provided was deidentified for patient, surgeon and institution and included all HR and conventional THR procedures performed for the diagnosis of primary osteoarthritis recorded in the Registry since inception in 1999. We requested mortality and yearly cumulative percent survival (CPS) of patients for primary HR and THR with sub-group analysis by the mode of fixation. There were 12,910 hip resurfacings (79% male) compared to 234,484 conventional THR (46.8% male) over the study period. When adjusted for age and gender over the 15 years of available data, there was a statistically significant difference in cumulative percent survival (CPS) between conventional THR and hip resurfacing (HR 1.66 (1.52, 1.82; p<0.001)) and between cemented THR and hip resurfacing (HR 1.96 (1.78, 2.43; p<0.001)); between uncemented THR and hip resurfacing (HR 1.58 (1.45, 1.73; p<0.001)); and between hybrid THR and hip resurfacing (HR 1.82 (1.66, 1.99; p<0.001)). When adjusted for age, gender and ASA over the 3 years data available, there was no statistically significant difference in CPS between hip resurfacing and any individual fixation type of THR. Discussion. The results demonstrate a statistically significant adjusted survival advantage for hip resurfacing compared to conventional THR and between fixation methods for THR. These findings are consistent with previous studies. While a difference in adjusted mortality rate appears to exist, we are yet to definitively determine the complex interplay of causative factors that may contribute to it

Aims. In metal-on-metal (MoM) hip arthroplasties and resurfacings, mechanically induced corrosion can lead to elevated serum metal ions, a local inflammatory response, and formation of pseudotumours, ultimately requiring revision. The size and diametral clearance of anatomical (ADM) and modular (MDM) dual-mobility polyethylene bearings match those of Birmingham hip MoM components. If the acetabular component is satisfactorily positioned, well integrated into the bone, and has no surface damage, this presents the opportunity for revision with exchange of the metal head for ADM/MDM polyethylene bearings without removal of the acetabular component. Methods. Between 2012 and 2020, across two centres, 94 patients underwent revision of Birmingham MoM hip arthroplasties or resurfacings. Mean age was 65.5 years (33 to 87). In 53 patients (56.4%), the acetabular component was retained and dual-mobility bearings were used (DM); in 41 (43.6%) the acetabulum was revised (AR). Patients underwent follow-up of minimum two-years (mean 4.6 (2.1 to 8.5) years). Results. In the DM group, two (3.8%) patients underwent further surgery: one (1.9%) for dislocation and one (1.9%) for infection. In the AR group, four (9.8%) underwent further procedures: two (4.9%) for loosening of the acetabular component and two (4.9%) following dislocations. There were no other dislocations in either group. In the DM group, operating time (68.4 vs 101.5 mins, p < 0.001), postoperative drop in haemoglobin (16.6 vs 27.8 g/L, p < 0.001), and length of stay (1.8 vs 2.4 days, p < 0.001) were significantly lower. There was a significant reduction in serum metal ions postoperatively in both groups (p < 0.001), although there was no difference between groups for this reduction (p = 0.674 (cobalt); p = 0.186 (chromium)). Conclusion. In selected patients with Birmingham MoM hips, where the acetabular component is well-fixed and in a satisfactory position with no surface damage, the metal head can be exchanged for polyethylene ADM/MDM bearings with retention of the acetabular prosthesis. This presents significant benefits, with a shorter procedure and a lower risk of complications. Cite this article: Bone Jt Open 2024;5(6):514–523

The survivorship of contemporary resurfacing arthroplasty of the hip using metal-on-metal bearings is better than that of first generation designs, but short-term failures still occur. The most common reasons for failure are fracture of the femoral neck, loosening of the component, osteonecrosis of the femoral head, reaction to metal debris and malpositioning of the component. In 2008 the Australian National Joint Registry reported an inverse relationship between the size of the head component and the risk of revision in resurfacing hip arthroplasty. Hips with a femoral component size of ≤ 44 mm have a fivefold increased risk of revision than those with femoral components of ≥ 55 mm irrespective of gender. We have reviewed the literature to explore this observation and to identify possible reasons including the design of the implant, loading of the femoral neck, the orientation of the component, the production of wear debris and the effects of metal ions, penetration of cement and vascularity of the femoral head. Our conclusion is that although multifactorial, the most important contributors to failure in resurfacing arthroplasty of the hip are likely to be the design and geometry of the component and the orientation of the acetabular component

The metal on metal implants was introduced without the proper stepwise introduction. The ASR resurfacing hip arthroplasty (RHA) withdrawn due to high clinical failure rates and the large diameter head THA (LDH-THA) are also widely abandoned. Early (2 year) radiostereometry studies does not support early instability as cause of failure but more likely metal wear products. A possible advantage may be maintenance of bone mineral density (BMD). We present 5 year prospective follow up from a randomized series, aiming to report changes from baseline and to investigate links between implant micromotion, Cr & Co ions and BMD. Patients eligible for an artificial hip were randomized to RHA, Biomet LDH-THA or standard Biometric THA. 19, 17 and 15 patients completed 5 year follow-up. All followed with BMD of the femur, acetabulum and for RHA the collum. RHA and THA with whole blood Co and Co. LDH-THA only at 5 year. RHA had marker based RSA of both components, cup only for LDH-THA. Translations were compiled to total translation (TT= √(x. 2. +y. 2. +z. 2. )). Data were collected at baseline, 8 weeks, 6 months, 1, 2 and 5 years. Statistical tests: ANCOVA for TT movement, Spearman's correlation for BMD, Cr, Co and BMI to TT at 5 years. RSA: The 5 year median (25%to75%) RHA cup translations were X=-0.00(−0.49 to 0.19) Y=0.15(−0.03 to 0.20), z=0.24(−0.42 to 0.37) and TT 0.58 (0.16 to 1.82) mm. For the LDH-THA X=−0.33(−0.90 to 0.20) Y=0.28(0.02 to 0.54), z=0.43(−1.12 to −0.19) and TT 1.06 (0.97 to 1.72) mm. The TT was statistically different (p<0.05) for the two cups. The RHA femoral component moved X=0.37(0.21 to 0.56) Y=0.02(−0.07 to 0.11), z=-0.01(−0.07 to 0.26) and TT 0.48 (0.29 to 0.60) mm at 5 years. There was no TT movement from year 2. The mean (SD) acetabular BMD was diminished to 93(90–97)% for RHA and 97(93–99.9)% for THA, but LDH-THA maintained 99(95–103)%. Overall femoral BMD was unchanged at 5 years for all interventions, but both stemmed implants lost 17% at the calcar. Median (25%to75%) whole-blood Cr peaked in the LDH-THA group with 1.7 (0.9 to 3.1) followed by RHA 1.2 (0.8 to 5.0) and THA with 0.5 (0.4 to 0.7)ppb. For Co the highest levels were found in RHA with 1.6(0.8 to 4.7) followed by LDH-THA 1.2 (0.7–1.7) and THA 0.2 (0.2 to 0.6) ppb. The only correlations above +/−0.3 for TT were the RHA femoral component with a correlation of 0.47 to BMI, 0.30 to Co and Cr. The ASR cup conversely had a negative correlation of −0.60 to BMI and again, the LDH-THA cup had a negative correlation of −0.37 to Cr. In contrast to registered revision rates, we found significantly larger movement for the Biomet cup than the ASR cup. The metal ion levels were similar. The LDH-THA cup maintained the acetabular BMD best at 5 years, but the difference was small, we are limited by small numbers and the correlations between TT and the covariates showed no clear pattern