Background. The worldwide withdrawal of the DePuy Articular Surface Replacement (ASR) device in both its resurfacing and total hip replacement (THR) form on 26 August 2010, after 93,000 were implanted worldwide, has had major implications. The 2010 National Joint Registry for England and Wales quoted figures of 12-13% failure at five years; however these figures may be an underestimate. Patients and methods. In 2004 a single surgeon prospective study of the ASR bearing surface was undertaken. Presented are the Adverse Reaction to Metal Debris (ARMD) failure rates of the ASR resurfacing and ASR THR systems. The diagnosis of ARMD was made by the senior author and was based on clinical history, examination, ultrasound findings, metal ion analysis of blood and joint fluid, operative findings and histopathological analysis of tissues retrieved at revision. Acetabular cup position in vivo was determined using EBRA software. Mean follow up was 52 months (24-81) and 70 patients were beyond 6 years of the procedure at the time of writing. Kaplan Meier survival analysis was carried out firstly with joints designated ‘failure’ if the patient had undergone revision surgery or if the patient had been listed for revision. A second survival analysis was carried out with a failure defined as a serum cobalt concentration > 7microgrammes/L (MHRA guideline from MDA-2010-069). Full explant analysis was carried out for retrieved prostheses. Results. There were 505 ASR hips in total (418 resurfacings and 87 THRs). 657 metal ion samples were available at the time of writing including 152 repeats. Survival analysis using revision/listed for revision as end point (at 6 years): ASR resurfacing: 26.1% failure; ASR THR: 55.5% failure. Survival using ion analysis (at 5 years): ASR resurfacing: 50.1% failure; ASR THR: 66.5% failure. The median (range) volumetric wear rate of failed prostheses was 8.23mm3/year (0.51-95.5). Failure and high ion concentrations are linked to acetabular cup size, anteversion and inclination. Increased failure rates in THRs were due to wear at the taper junction of head and stem. Conclusion. Design flaws in the ASR have led to excessive wear and consequently catastrophic failure rates secondary to ARMD

Hip resurfacing has generally been used in younger patients with early osteoarthritis of the hip. There has been considerable recent interest in this over the past few years. We conducted a prospective randomised trial comparing 2 hip resurfacing implants, Durom and ASR looking at radiological and clinical outcomes. Forty-nine patients (78% male) with hip osteoarthritis which met the criteria for hip resurfacing were randomised to receive either a Durom or ASR resurfacing implant. These patients have so far been followed up for a minimum of one year. The groups were comparable in age (p=0.124) and gender (p=0.675). The average age in the ASR group was 54.04 years and in the Durom group it was 51.25. Radiological views were scrutinised immediately post op and at final follow up so far to look at cup inclination, stem-shaft angle, and acetabular osseointegration. Clinical outcomes were compared using the Oxford hip scores, WOMAC scores and SF12 scores. At minimum follow up of 1 year the mean post operative Oxford hip score was not significantly different between the Durom (45.32, SD 3.93) and ASR (43.44, SD 8.44). The mean post operative WOMAC score was also not significantly different between the Durom (52.56, SD 6.06) and ASR (49.63, SD 2.23). There was no difference between the groups with regards to signs of osseointegration from radiological assessment (p=0.368). There were 3 periprosthetic femoral neck fractures (5.7%) and one revision for pain. We conclude from this trial that there is no difference in the clinical or radiological findings between the Durom and ASR implants

The objective of this study was to analyze the biomechanical effect of an implanted ACL graft by determining the tunnel position according to the aspect ratio (ASR) of the distal femur during flexion-extension motion. To analyze biomechanical characteristics according to the ASR of the knee joint, only male samples were selected to exclude the effects of gender and 89 samples were selected for measurement. The mean age was 50.73 years, and the mean height was 165.22 cm. We analyzed tunnel length, graft bending angle, and stress of the graft according to tunnel entry position and aspect ratio (ratio of antero-posterior depth to medio-lateral width) of the articular surface for the distal femur during single-bundle outside-in anterior cruciate ligament reconstruction surgery. We performed multi-flexible-body dynamic analyses with wherein four ASR (98, 105, 111, and 117%) knee models. The various ASRs were associated with approximately 1-mm changes in tunnel length. The graft bending angle increased when the entry point was far from the lateral epicondyle and was larger when the ASR was smaller. The graft was at maximum stress, 117% ASR, when the tunnel entry point was near the lateral epicondyle. The maximum stress value at a 5-mm distance from the lateral epicondyle was 3.5 times higher than the 15-mm entry position and, the cases set to 111% and 105% ASR, showed 1.9 times higher stress values when at a 5-mm distance compared with a 15-mm distance. In the case set at 98% ASR, the low-stress value showed a without-distance difference from the lateral epicondyle. Our results suggest that there is no relationship between the ASR and femoral tunnel length, A smaller ASR causes a higher graft bending angle, and a larger ASR causes greater stress in the graft

Summary. Despite high revision rates, the mean two year migration of the ASR. TM. cup is within an acceptable threshold. Slightly higher migration rates found for the M2a- Magnum™ Porous Coated Acetabular Component but longer follow up is needed to establish if this implant is at risk. Introduction. RSA can detect the migration of an implant, and continuous migration is a predictor for failure (1). The ASR. TM. resurfacing implant was withdrawn from the marked due to excessive failure rate but showed initial femoral component stability. The aim of this study was to investigate the initial implant stability for the ASR cup as a possible explanation for the high revision rate, and to compare it to another metal on metal (MoM) cup. Patients and Methods. 36 patients with primary osteoarthritis from a RCT received either an ASR. TM. (n=19) or an M2a-Magnum Cup. TM. (n=17) without markers. Ten 0.8mm tantalum markers were injected in the periacetabular bone. Using a UmRSA® 43Calibration Cage™ (RSA Biomedical, Sweden), supine RSA images were obtained within 3 days of surgery, at 8 w, 6 m, 1 and 2 years. A model based RSA system using an EGS Hemi-sphere model (Medis specials, Leiden) calculated migration. For the 2 year analysis 16 and 15 sets of images were available. ANOVA with repeated measurements analysed movement over time for each type of implant as well as difference between implants. Results. Mean translations in the medial –lateral (X), proximal-distal (Y) and anterior-posterior (Z) direction are depicted. Initial movement was noted, especially for the M2a-Magnum cup, where the 2 year mean (sd) X translation was −0.307 (0.53)mm (p = 0.01), Y translation was 0.282 (0.36)mm (p < 0.001) and Z translation was −0.343 (0.63)mm p = (0.03). After 2 years the ASR cup displayed a mean X translation of −0.115 (0.60) mm (p = 0.82), Y translation of 0.075 (0.14)mm (p = 0.01) and Z translation of 0.438 (0.88)mm (p = 0.04). The implants had a similar pattern for X and Y with slightly more movement for M2a-Magnum in the X translations (p < 0.01) On the Z axis the implants displayed movement in opposite directions (p=<0.001). At two years 4 ASR and 5 M2aMagnum displayed movement above 1 mm in one axis . Discussion/Conclusion. The early migration of both cups were low. The ASR implant is slightly higher than a competing implant with better survival rates on the Z axis, but low at particularly the Y axis, where the mean 0.075 mm is well below the limit of 0.2mm recently suggested as an acceptable threshold. The M2a-Magnum cup has migration rates just above that, but longer clinical follow up is needed to establish if this cup has greater risk of revision. We will continue to monitor our patients to establish if the individual patient with excess migration is at risk. Continuous migration is not likely to explain failure of neither the cup nor the femoral side of the ASR hip

Introduction and Objective. Postoperative pain control in shoulder surgery is challenging even in arthroscopic procedures. Acute postoperative pain can last up to 48hrs despite using multimodal analgesia. Different techniques have been used to control acute pain following shoulder surgery. The most common technique currently used in shoulder surgery at the elective orthopaedic centre in Leeds is a combination of general anaesthetic (GA) and interscalene block (ISB). ISB maybe very effective, however, carries many risks and potential side effects such as brachial plexus injury and paralysis of the vagus and laryngeal recurrent nerves as well as cervical sympathetic nerve and pneumothorax. ISB can also be associated with higher incidence of neurological deficit compared to other peripheral nerve blocks; up to 14% at 10 days in some cases. As such we decided to examine the use of ISB for achieving pain control in our elective unit. Materials and Methods. A prospective consecutive series of 217 patients undergoing shoulder surgery were studied. These were grouped into 10 groups. All procedures were arthroscopic apart from shoulder arthroplasty procedures such as hemiarthroplasty and total shoulder replacements (TSRs). The choice of regional anaesthesia was ISB with GA as standard practice. Visual analogue scores (VAS) at 0hrs, 1hr, 2hrs, 4hrs and 6hrs; and total opiates intake were recorded. A one-way single factor ANOVA was used as preferred statistical analytical method to determine whether there is a difference in VAS scores and total opiates intake amongst the groups. Postoperative analgesics were used for pain relief, although these were not standardised. Results. In total shoulder replacement group, although the RSR group used more morphine on average compared to the ASR group (Mean morphine intake 6.5mg vs 3mg), this was not statistically significant (F<Fcrit; p value= 0.19). When comparing all the arthroplasty groups, the difference in mean morphine intake was also statistically not significant (F<Fcrit; p value=0.24). However, when comparing all 10 groups’ morphine intake there was a statistically significant difference amongst these groups (F>F crit; p value=0.03). Interestingly, there was a statistically significant difference in VAS at 0hrs (F>Fcrit p value=0.01); 1hrs (F>Fcrit; p value=0.00), and at 6hrs (F>Fcrit; p value=0.02) when comparing all 10 groups. Conclusions. ISB is an effective technique in achieving pain control in shoulder surgery; however, there are still variations in analgesic needs amongst groups and the use of alternative techniques should be thus explored. A future prospective study looking at acute pain for a longer period of time after shoulder surgery would explore the effectiveness of ISB in achieving pain control consistent with rehabilitation requirements

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

Metal-on-metal hip resurfacing prostheses are a relatively recent intervention for relieving the symptoms of common musculoskeletal diseases such as osteoarthritis. While some short term clinical studies have offered positive results, in a minority of cases there is a recognised issue of femoral fracture, which commonly occurs in the first few months following the operation. This problem has been explained by a surgeon's learning curve and notching of the femur but, to date, studies of explanted early fracture components have been limited. Tribological analysis was carried out on fourteen retrieved femoral components of which twelve were revised after femoral fracture and two for avascular necrosis (AVN). Eight samples were Durom (Zimmer, Indiana, USA) devices and six were Articular Surface Replacements (ASR, DePuy, Leeds, United Kingdom). One AVN retrieval was a Durom, the other an ASR. The mean time to fracture was 3.4 months. The AVNs were retrieved after 16 months (Durom) and 38 months (ASR). Volumetric wear rates were determined using a Mitutoyo Legex 322 co-ordinate measuring machine (scanning accuracy within 1 micron) and a bespoke computer program. The method was validated against gravimetric calculations for volumetric wear using a sample femoral head that was artificially worn in vitro. At 5mm3, 10mm3, and 15mm3 of material removal, the method was accurate to within 0.5mm3. Surface roughness data was collected using a Zygo NewView500 interferometer (resolution 1nm). Mean wear rates of 17.74mm3/year were measured from the fracture components. Wear rates for the AVN retrievals were 0.43mm3/year and 3.45mm3/year. Mean roughness values of the fracture retrievals (PV = 0.754nm, RMS = 0.027nm) were similar to the AVNs (PV = 0.621nm, RMS = 0.030nm), though the AVNs had been in vivo for significantly longer. Theoretical lubrication calculations were carried out which found that in both AVN retrievals and in seven of the twelve cases of femoral fracture the roughening was sufficient to change the lubrication regime from fluid film to mixed. Three of these surfaces were bordering on the boundary lubrication regime. The results show that even before the femoral fracture, wear rates and roughness values were high and the implants were performing poorly

Summary. Management of metal on metal hip replacements can be accomplished with a simple algorithm including easily available metal ion levels and hip MRI with metal artifact reducing software. After revision serum metal ion levels can be expected to fall rapidly. Introduction. Metallic ion release may be related to bearing surface wear and thus serves as an indicator of the in-vivo performance of metal on metal articulations. The purpose of this prospective, controlled study was to compare new large head metal on metal hip components with established modular metal on metal and metal on polyethylene and to determine their effects on serum metal levels before and after revision. Patients & Methods. We performed a multi-surgeon, prospective, controlled trial to compare clinical, radiographic, and metal ion concentration in serum (cobalt and chrome) results across multiple devices including the Large Head ASR XL System (MoM-1), the Ultamet Advanced Modularity System (MoM-2), and as the control the Pinacle Acetabular Cup System with polyethylene liner (MoP). One hundred and fifty-one consecutive patients undergoing THA were enrolled in the study: MoM-1 n=97; MoM-2 n=22; MoP n=32. Clinical, radiographic, and venous blood assessments were performed pre-operatively, and post-operatively at 6 months, 1 year and 2 years, and after revision (1,3,6,12 months). All serum ion concentrations are reported in nmol/L. We are following metal ion levels after revision and have developed an algorithm to diagnose and manage patients with MoM THA. Results. MoM-1 patients had significantly increased average cobalt and chromium levels. Clinical scores improved after surgery in all groups and continued to improve in MoM-2 and MoP patients after 2 years but decreased slightly in the MoM-1 patients at 2 years. Average cup inclination angle did not differ significantly between the groups: MoM-1 50.2, MoM-2 47.8, and MoP 51.7. In the MoM-1 group 11 patients (11%) had significantly elevated ion levels (MoM-1 Outliers). Nine hips (9.3%) in 8 MoM-1 outlier patients required revision. Metal ion levels were not significantly different between MoM-2 and MoP groups. Metal ion levels after revision in the MoM-1 group decreased rapidly but at one year post-operatively have still not returned to an equivalent baseline comparable to the MoM-2 and MoP groups. All revisions were in the MoM-1 group. Chromium levels decreased more slowly than Cobalt levels. Discussion. To our knowledge this is the only data in the literature prospectively comparing ion levels among groups and reporting post revision ion levels. Average serum ion levels were elevated at all post-operative samples in the MoM-1 group but this was due to significantly elevated levels in a subset of outliers who required revision. Excluding the outliers there is not a significant difference in post-operative ion levels between the groups. There was no radiographic evidence of component malposition or aseptic loosening in any of the groups. Control groups (MoM-2, MoP) performed comparatively across all variables. We present an algorithm to diagnose and manage patients with metal on metal THA and offer evidence that metal ion levels do decrease after revision but still remain abnormally elevated at one-year post revision compared to the control group. A significant portion of MoM-1 performs comparatively to the controls in terms of ions

Bone surface strains were measured in cadaver femora during loading prior to and after resurfacing of the hip and total hip replacement using an uncemented, tapered femoral component. In vitro loading simulated the single-leg stance phase during walking. Strains were measured on the medial and the lateral sides of the proximal aspect and the mid-diaphysis of the femur. Bone surface strains following femoral resurfacing were similar to those in the native femur, except for proximal shear strains, which were significantly less than those in the native femur. Proximomedial strains following total hip replacement were significantly less than those in the native and the resurfaced femur.

These results are consistent with previous clinical evidence of bone loss after total hip replacement, and provide support for claims of bone preservation after resurfacing arthroplasty of the hip.

The cortical strains on the femoral neck and proximal femur were measured before and after implantation of a resurfacing femoral component in 13 femurs from human cadavers. These were loaded into a hip simulator for single-leg stance and stair-climbing. After resurfacing, the mean tensile strain increased by 15% (95% confidence interval (CI) 6 to 24, p = 0.003) on the lateral femoral neck and the mean compressive strain increased by 11% (95% CI 5 to 17, p = 0.002) on the medial femoral neck during stimulation of single-leg stance. On the proximal femur the deformation pattern remained similar to that of the unoperated femurs.

The small increase of strains in the neck area alone would probably not be sufficient to cause fracture of the neck However, with patient-related and surgical factors these strain changes may contribute to the risk of early periprosthetic fracture.