There is widespread concern regarding the incidence of adverse soft-tissue reactions after metal-on-metal (MoM) hip replacement. Recent National Joint Registry data have shown clear differences in the rates of failure of different designs of hip resurfacing. Our aim was to update the failure rates related to metal debris for the Articular Surface Replacement (ASR). A total of 505 of these were implanted. Kaplan-Meier analysis showed a failure rate of 25% at six years for the ASR resurfacing and of 48.8% for the ASR total hip replacement (THR). Of 257 patients with a minimum follow-up of two years, 67 (26.1%) had a serum cobalt concentration which was greater than 7 μg/l. Co-ordinate measuring machine analysis of revised components showed that all patients suffering adverse tissue reactions in the resurfacing group had abnormal wear of the bearing surfaces. Six THR patients had relatively low rates of articular wear, but were found to have considerable damage at the trunion-taper interface. Our results suggest that wear at the modular junction is an important factor in the development of adverse tissue reactions after implantation of a large-diameter MoM THR

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

We present the mid-term results of our consecutive series of 155 hips treated with ASR extra-large (XL) Acetabular System (ASR XL) and with ASR Hip Resurfacing System (ASR). We reviewed the clinical records of patients with implanted ASR or ASR XL. All patients were recalled and invited to come to our hospital for a periodic clinical, hematological and radiological evaluation.114 ASR XL and 41 ASR were implanted between 2004 and 2008 in 145 patients (69 men and 76 women) with a mean age of 57 years. 21 patients (23 hips) were lost from follow-up. Average follow-up was 76 months (50 to 91). Up now 42 ASR implants have been revised (27.0%): revision involved 9 hips on 41 treated with resurfacing (21.9%) and 33 hips on 114 treated with XL total hip arthroplasty (28.9%). Main reasons for revision were aseptic loosening with or without metallosis in 23 hips (56%), infection in 3 hips (7%), recurrent dislocation in 1 hip (2%), periprosthetic fractures in 1 hip (2%), elevation of blood metal ion in 6 (14%), pain in 2 (5%), unknown in 6 (14%). The cumulative survival for our ASR implants series was 61.6% with revision for any reason as the end-point after a mean follow-up of 76 months. The cumulative survival with revision for any reason as the end-point for ASR and ASR XL were respectively 67.0% and 59.1%. For patients who did not undergone revision, the mean Harris hip score improved to 91 (57 to 100) at five years and the mean satisfaction after the operation was graded 4.4 in a score from 1 to 5. Periprosthetic osteolysis was not found around any unrevised hip. Average cup inclination was 48° for the functioning hips and 55° for the revised hips. Metal ions plasma concentration analysis was conducted in 83 patients (87 hips). Elevated metal ion concentration (>7 μg/l) was found in 39 patients (42 hips, 48%) with average plasma concentrations of 37.3 μg/l for chromium and 81.5 μg/l for cobalt. Lower metal ions levels (<7 μg/l) were found in 44 patients (45 hips, 52%) with average plasma concentrations of 1.2 μg/l for chromium and 1.9 μg/l for cobalt. Our current concerns involve our large series of 30 asymptomatic patients (31 hips) with a radiographically stable implant without osteolysis signs but with elevated blood metal ion concentrations

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 3.51mm. 3. (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

Introduction:. We present the mid-term results of our consecutive series of 155 hips treated with ASR XL Acetabular System (ASR-XL) for large-diameter metal-on-metal total hip arthroplasty and with DePuy ASR Hip Resurfacing System (ASR) for hip resurfacing. Methods:. 114 ASR-XL and 41 ASR were implanted between 2004 and 2008 in 145 patients (69 men and 76 women) with a mean age of 57 years. Twenty-one patients (23 hips) resulted lost to follow-up. All patients were recalled and monitored periodically with clinical, hematological and radiological evaluation. Average follow-up of the 155 hips was 72 months (1 to 104). The mean follow-up, excluding revised patients and those lost to follow-up, was up to 89 months. Results:. At latest follow-up we had revised 54 of 155 hips (35%) with complete removal of ASR device. Revision involved 15 hips with ASR (36.5% within ASR group) and 39 hips with ASR-XL (34.2% within ASR-XL group). Main reasons for revision were aseptic loosening in 24 hips (44%), pain or pain associated with elevation of blood metal ions in 9 (17%), elevation of blood metal ions without pain in 9 (17%), deep infection in 4 hips (7%), recurrent dislocation in 1 hip (2%), periprosthetic fractures in 1 hip (2%), unknown because revised elsewhere in 6 (11%). The cumulative survival with revision for any reason as the end-point for ASR and ASR XL were respectively 59.6% and 59.3%. For patients who did not undergone revision, the mean Harris hip score improved to 91 (57 to 100) at five years and the mean satisfaction after the operation was graded 4.4 in a score from 1 to 5. Metal ions plasma concentration analysis was conducted in 83 patients (87 hips). Elevated metal ion levels (>7 μg/l) was found in 39 patients (42 hips, 48%) with average Cr and Co concentrations respectively of 37.3 μg/l and 81.5 μg/l. The remaining 44 patients (45 hips, 52%) had an average Cr and Co concentrations respectively of 1.2 μg/l and 1.9 μg/l. Metal ion levels in revised patients were significantly (p < 0.001) higher than in non-revised patients. MARS-MRI performed in 38 hips with high metal ions revealed pseudotumour formations in 13 hips (34%). No macroscopic evident clinical sign of cobaltism was reported for any patient. Conclusion:. ASR implants survival could have a considerable drop in the mid-term follow-up due to adverse reactions to high blood metal ions concentrations and metal debris. Adverse reactions could include periprosthetic pseudotumour formations and low-detectable periprosthetic osteolysis even in asymptomatic patients

Introduction. Failure rates of Metal-on-Metal (MoM) ASR XL hip implants have been unacceptably high compared with other bearing surfaces, so patients must be monitored over the time checking for disorders in clinical condition, blood tests or in diagnostic imaging. Objectives. We have carried out a continuing prospective investigation to evaluate the relationship between blood metal ions measurements and ultrasound levels and to evaluate if ultrasound score can predict a future indication to revision. Materials and methods. From DePuy Recall of 2010 we have monitored 106 patients (51 males, 55 females, mean age 63.6) with ASRXL implants. The controls were performed annually. The following scales were used for patients evaluation:. Ultrasound score: 0 none; 1 fluid collection <20 mm, 2 fluid collection <20 mm, 3 solid mass: metallosis. Blood metal levels of Chromium-Cobalt (Cr-Co) (μg/l = ppb): normal <3 ppb, alert between 3 and 7 ppb, pathologic <7 ppb. Clinical Score: Harris Hip Score. Rx score, evaluating the prosthetic-bone integration and the inclination of acetabular component. Patients who presented positive clinical-instrumental conditions and values of Cr and Co > 3 mg/l were checked every 6 months. Statistical analysis was carried out with Non-parametric Kruskal-Wallis test and two factors Analysis of Variance using SAS System vers. 9.4. Results. The follow-up included 110 implants (4 are bilateral case). 43 patients (39,1 %) underwent revision surgery for failed MoM utilizing ceramic-on-polyethylene devices. At a mean time of 65,7 +/− 15,9 months, 47 patients had a ultrasound score of 0 (13 revised), 32 patients had a ultrasound score of 1 (9 revised), 20 patients had a ultrasound score of 2 (15 revised), 7 patients had a ultrasound score of 3 (6 revised); 44 patients had Cr value < 3 ppb (5 revised), 28 patients had Cr value <3 ppb<7 (6 revised), 34 patients had Cr value <7 ppb (32 revised), 25 patients had Co value < 3 ppb (5 revised), 20 patients had Co value <3 ppb<7 (1 revised), 61 patients had Co value > 3 ppb (37 revised). A positive correlation between blood metal ions values and ultrasound levels (p<0,001) and a statistically significant interaction between ultrasound score and indication to revision (p=0,037) were found. Discussion and Conclusion. As reported in literature also in our experience the ASR XL implant was afflicted by an excessive revision rate, associated with levels of metal ions significantly higher than other hip bearing surfaces. Our results demonstrate a positive correlation between blood Cr and Co levels and the amount of fluid collection: at higher levels of fluid collection correspond higher levels of blood metal ions. Since statistical analysis confirmed that the level of ultrasound score is correlated with indication to revision it is suggested to use ultrasounds, if the score is 2 or more, as parameter to revise MoM implants even in absence of pathologic blood ions levels

Radiostereometric analysis (RSA) can detect early micromovement in unstable implant designs which are likely subsequently to have a high failure rate. In 2010, the Articular Surface Replacement (ASR) was withdrawn because of a high failure rate. In 19 ASR femoral components, the mean micromovement over the first two years after implantation was 0.107 mm (. sd. 0.513) laterally, 0.055 mm (. sd. 0.204) distally and 0.150 mm (. sd. 0.413) anteriorly. The mean backward tilt around the x-axis was -0.08° (. sd. 1.088), mean internal rotation was 0.165° (. sd. 0.924) and mean varus tilt 0.238° (. sd. 0.420). The baseline to two-year varus tilt was statistically significant from zero movement, but there was no significant movement from one year onwards. We conclude that the ASR femoral component achieves initial stability and that early migration is not the mode of failure for this resurfacing arthroplasty

Introduction. While fixation on the acetabular side in resurfacing implants has been uncemented, the femoral component is usually cemented. The most common causes for early revision in hip resurfacing are femoral head and or neck fractures and aseptic loosening of the femoral component. Later failures appear to be more related to adverse soft-tissue reactions due to metal wear. Little is known about the effect of cementing techniques on the clinical outcome in hip resurfacing, since retrieval analysis of failed hip resurfacing show large variations. Two cementing techniques have dominated. The indirect low viscosity (LV) technique as for the Birmingham Hip resurfacing (BHR) system and the direct high viscosity (HV) technique as for the Articular Surface replacement (ASR) system. The ASR was withdrawn from the market in 2010 due to inferior short and midterm clinical outcome. This study presents an in vitro experiment on the cement mantle parameters and penetration into ASR resurfaced femoral heads comparing both techniques. Methods. Five sets of paried frozen cadavar femura (3 male, 2 female) were used in the study. The study was approved by ethics committee. Plastic ASR replicas (DePuy, Leeds, UK), femoral head size 47Ø were used. The LV technique was used for the right femora (Group A, fig. 1 and 3) while the HV technigue was used for the left femora (Group B. Fig 2 and 4). The speciments were cut into quadrants. An initiial visual, qualitative evaluation was followed by CT analysis of cement mantle thickness and cement penetration into bone. Results. No significant differences were seen between the four quadrants within each group. The LV technigue resulted in greater cement penetration and increased cement mantle under the top proximally. The HV technique showed less penetration and lower cement mantle. See figures 1–4. Discussion. The aim was to analyze the effect of the cementing techniques used in hip resurfacing practice. The ASR implant was chosen to improve understanding of whether the implant may have been sensitive to cementing techniques and whether an analysis of cementing with the recommended HV technique may assist in explaning the high incidence of short-term ASR revisions due to fractures. Findings for the HV technigue would indicate a superior technique according to consensus in conventional arthropalsty However, this contradicts clinical evidence on resurfacing, where LV cementation has been shown tho be superior. The superficial intergration in the HV technigue may result in only a superficial integration and subsequently suboptimal fixation to bone. To view tables/figures, please contact authors directly

Aims

The aims of this study were to determine if an increasing serum cobalt (Co) and/or chromium (Cr) concentration is correlated with a decreasing Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) in patients who received the Articular Surface Replacement (ASR) hip resurfacing arthroplasty (HRA), and to evaluate the ten-year revision rate and show if sex, inclination angle, and Co level influenced the revision rate.

Introduction: Excellent medium term results have been reported with the BHR hip resurfacing implant. A number of modifications have been made to the latest designs in an attempt to preserve acetabular bone stock, improve function and prolong survival. We present the clinical and radiological results from the first independent series of ASR resurfacings. Methods: The first consecutive series of 214 ASR hip resurfacings (192 patients) were followed up prospectively. No patients were lost to follow-up. The mean age of patients at implantation was 56 years and 40% were female. All patients had pre- and 2-year post-operative Harris Hip Scores (HHS) and UCLA activity scores. Radiographic and implant survival analysis was performed at 24–54 months following implantation. Results: One hundred and seventy-three hips (87%) had an excellent Harris Hip Score (90 or above). Mean postoperative UCLA activity score was 7 and 92% were highly satisfied with the outcome. There were eleven revisions (5.1%). Four (1.9%) had femoral neck fractures (three had a femoral neck notch), two (0.9%) collapsed secondary to avascular necrosis and five (2.3%) were revised because of ongoing pain, as a result of metal wear debris. Discussion: Although the fracture rate is similar to reports in the literature, the overall revision rate was higher. Rates of wear debris-related failure is concerning. Further investigation of specific implant failure is necessary

Aim. We report the results of 60 patients who were assessed using the Oxford Hip Score following surgery for revision of ASL XL and ASR Resurfacing systems at our institution. We included preoperative metal ion levels, surgical approach, revision implant, and post op histology and complications to determine variables for improved outcomes. Methods. We performed a retrospective review of consecutive series patients who underwent revision surgery between 2007 – 2015. We collected and analysed data from 60 patients regarding time between surgery, surgical technique including approach and anaesthesia, estimated blood loss (EBL), revision implant, post op complications, histology, and length of post-operative stay. We correlated these findings to the patients reported outcomes measures using the Oxford Hip Score, which were obtained by post. Results. Our data shows a reduction in values for Oxford Hip Scores in at least 24 patients as compared to an improvement in values for 22 patients. 6 patients could not be contacted, 4 patients refused to participate, and 4 patients did not have pre-op Oxford Hip Score values for comparison. Our main findings from 46 patients are summarized in table 2. Conclusion(s). Age, Sex, Ion Level, Surgical Approach, and Implant choice may be useful variables in predicting patient satisfaction following revision surgery. Implications. The major practical implication of this study is that we may be able to predict Outcomes of Revision surgery based on variables mentioned above. This has major implication in suitable patient selection for surgery, and appropriate implant choice

Background. Previous studies have indicated poor outcomes and high complication rate in patients having revision of metal-on-metal (MoM) hip implants resulting from adverse local tissue reactions. Metal ions released by MoM bearings may potentially increase infection occurrence in patients with failed implants. Questions/purposes. We reviewed all patients at our institution who sustained revision of a failed large-head metal-on-metal hip implant to determine if infection-related complications are associated with the elevation of serum metal ions concentration. Methods. From December 2005 to April 2013, we performed 44 revisions of large-head MoM total hip arthroplasty (THA) and resurfacing in 44 patients. In all revision procedures MoM couplings (ASR XL Acetabular System and DePuy ASR Hip Resurfacing System) were explanted. Preoperative diagnosis were: aseptic loosening in 21 hips, hip pain with high serum metal ions levels in 7 hips, high serum metal ions levels without hip pain in 9 hips, deep infections in 4 hips, unexplained hip pain in 2 hips and periprosthetic fracture in 1 hip. Serum cobalt and chromium analysis were preoperatively conducted in 25 patients. Intraoperative fluid aspiration was performed in all cases to determine the presence or absence of periprosthetic joint infection. Results. Fluid analysis for bacteria reported that 35 of 45 cases were culture negative and 10 of 45 cases (22%) were culture positive to Staphylococcus (St) Aureus (4), St Capitis (2), St Epidermidis (2), St Hominis (1), Streptococcus Mitis (1). All preoperative diagnoses of deep infection were confirmed. Within patients evaluated with serum metal ions analysis (mean Co and Cr, 78 μg/l and 39 μg/l, respectively), five cultures resulted positive (20%). The infection rate within patients with higher (> 20 μg/l) metal ions levels (4 positive cultures of 18, 22%) was not significantly higher than infection rate within patients with lower (≤ 20 μg/l) metal ions levels (1 positive culture of 7, 14%). Conclusions. We observed a high rate of periprosthetic joint infection among our revision cases. High metal ions concentrations released by MoM bearings might promote bacterial infections in patients with MoM THA and resurfacing. When evaluating patients with failed MoM hip devices, there may be an increased incidence of co-infection in these patients

Introduction: There is a general conception in the orthopaedic community that blood loss/transfusion rate in hip resurfacing procedures is greater than that conventional Total Hip Arthroplasty (THA). The theoretical basis is that uncemented procedures leave large bleeding bone surfaces and that resurfacing arthroplasty needs larger incisions, greater exposure and more extensive soft tissue releases. Although this theory has gained informal. Acceptance in orthopaedic practice, there is little evidence in the literature to support this. Background The purpose of this study was to determine the actual blood loss and transfusion rate (including hidden blood loss) in a consecutive cohort of patients undergoing hip re-surfacing by a single surgeon using the Articular Surface Replacement (ASR – DePuy). Materials and Methods: The cohort consisted of 58 patients who were followed prospectively. All patients underwent a standardized surgical procedure performed by one senior surgeon. Hypotensive anaesthesia was used in all cases and surgery was via a standard posterior approach. Drains were not routinely placed, but if used, were removed within 24 hours. Low Molecular Weight Heparin was given 24 hours post procedure until discharge. Surgical blood loss was calculated in a standard fashion (suction volume plus swab weight). Drain volume (if used) was added after removal at 24 hours. Unseen loss of blood in soft tissues, joint space, as well as loss due to haemolysis, is calculated by the modified formula of Kallos. 1. :. \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[MABL=\ EBV\ x\ (\underline{Hct\ pt\ -\ Hct\ min})\] \end{document}. Hct pt, Where is. MABL = Maximum allowable blood loss. EBV =Estimated blood volume, 70 ml/kg. Hct pt= Pre operative haematocrit of patient. Hct min=Minimum allowable haematocrit. This was modified to. \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(ABL=\ EBV\ {\times}\ \frac{(Hct\ pre\ op\ {-}\ Hct\ post\ opD2)}{Hct\ pre\ op}\) \end{document}. where is. ABL= Actual blood loss, Unseen loss = ABL – Visible loss (Loss in OT + Drain). Results: 58 Patients undergoing ASR, the aeitology was Osteoarthritis in 50 Patients, Dysplasia in 3, Inflammatory Arthritis in 1 and in 1 patient the aetiology was arthrosis secondary to trauma. The average blood loss during the procedure was 221 mls. After 24 hours this had risen to 377 ml, Mean Unseen blood loss was 787.6 ml, Mean Total actual blood loss was 1385.6 ml. There was a mean drop in haemoglobin of 3.6 g/dl and mean drop of Hematocrit was 10.33%. Only 3 patients required blood transfusion. Conclusion: The mean blood loss in this study was 598 ml and actual blood loss was 1385.60. This is considerably lower than expected for resurfacing arthroplasty and results in a low transfusion rate of only 5% patients undergoing the procedure. Meticulous haemostasis combined with hypotensive anaesthesia reduced the perioperative blood loss and transfusion rate

Introduction

In 2010, a widely used metal-on-metal hip implant was voluntarily recalled from the market by the manufacturer. Our lab performed detailed retrieval analysis of 548 of the explanted devices and 165 periprosthetic tissue specimens. We reported a high degree of variability in the multiple measurements that we performed on the components, including volumetric wear.

Other studies using semi-quantitative tissue grading methods to describe the histology of the periprosthetic tissues from metal-on-metal hips have looked for relationships between component wear and histological features. Grammatopoulos et al found higher ALVAL scores in 45 hip resurfacing patients with pseudotumors compared to 11 without pseudotumors and a moderately positive correlation between wear and the histological rankings for tissue necrosis and lymphocytic response.

We examined correlations between the component wear measurements from retrieval analysis and the tissue features in this large group of one metal-on-metal hip design.

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

Objectives. This study aimed to characterise and qualitatively grade the severity of the corrosion particles released into the hip joint following taper corrosion. Methods. The 26 cases examined were CoC/ABG Modular (n = 13) and ASR/SROM (n = 13). Blood serum metal ion levels were collected before and after revision surgery. The haematoxylin and eosin tissue sections were graded on the presence of fibrin exudates, necrosis, inflammatory cells and corrosion products. The corrosion products were identified based on visible observation and graded on abundance. Two independent observers blinded to the clinical patient findings scored all cases. Elemental analysis was performed on corrosion products within tissue sections. X-Ray diffraction was used to identify crystalline structures present in taper debris. Results. The CoC/ABG Modular patients had a mean age of 64.6 years (49.4 to 76.5) and ASR/SROM patients had a mean age of 58.2 years (33.3 to 85.6). The mean time in situ for CoC/ABG was 4.9 years (2 to 6.4) and ASR/SROM was 6.1 years (2.5 to 8.1). The blood serum metal ion concentrations reduced following revision surgery with the exception of Cr levels within CoC/ABG. The grading of tissue sections showed that the macrophage response and metal debris were significantly higher for the ASR/SROM patients (p < 0.001). The brown/red particles were significantly higher for ASR/SROM (p < 0.001). The taper debris contained traces of titanium oxide, chromium oxide and aluminium nitride. Conclusion. This study characterised and qualitatively graded the severity of the corrosion particles released into the hip joint from tapers that had corrosion damage. Cite this article: S. Munir, R. A. Oliver, B. Zicat, W. L. Walter, W. K. Walter, W. R. Walsh. The histological and elemental characterisation of corrosion particles from taper junctions. Bone Joint Res 2016;5:370–378. DOI: 10.1302/2046-3758.59.2000507

The Articular Surface Replacement (ASR) hip resurfacing arthroplasty has a failure rate of 12.0% at five years, compared with 4.3% for the Birmingham Hip Resurfacing (BHR). We analysed 66 ASR and 64 BHR explanted metal-on-metal hip replacements with the aim of understanding their mechanisms of failure. We measured the linear wear rates of the acetabular and femoral components and analysed the clinical cause of failure, pre-revision blood metal ion levels and orientation of the acetabular component. There was no significant difference in metal ion levels (chromium, p = 0.82; cobalt, p = 0.40) or head wear rate (p = 0.14) between the two groups. The ASR had a significantly increased rate of wear of the acetabular component (p = 0.03) and a significantly increased occurrence of edge loading (p < 0.005), which can be attributed to differences in design between the ASR and BHR. The effects of differences in design on the in vivo wear rates are discussed: these may provide an explanation as to why the ASR is more sensitive to suboptimal positioning than the BHR

Aim. Infected segmental defects are one of the most feared complications of open tibial fractures. This may be due to prolonged treatment time, permanent functional deficits and high reinfection and non-union rates. Distraction osteogenesis techniques such as Ilizarov acute shortening with bifocal relengthening (ASR) and bone transport (BT) are effective surgical treatment options in the tibia. The aim of this study was to compare ASL with bone transport in a consecutive series of complex tibial infected non-unions and osteomyelitis, for the reconstruction of segmental defects created at surgical resection of the infection. Method. In this single centre series, all patients with a segmental defect (>2cm) of the tibia after excision of infected non-union or osteomyelitis were eligible for inclusion. Based on clinical features, bone reconstruction was achieved with either ASR or BT using an Ilizarov fixator. We recorded the external fixation time (months), the external fixation index (EFI), comorbidities, Cierny-Mader or Weber-Cech classification, follow-up duration, time to union, number of operations and complications. Results. Overall, 43 patients with an infected tibial segmental defect were included. An ASR was performed in 19 patients with a median age of 40 years (range: 19 – 66 years). In this group, the median bone defect size was three cm (range: 2 – 5 cm); and the median frame time eight months (range: 5 – 16 months). BT was performed in 24 patients with a median age of 44 years (range: 21 – 70 years). The median bone defect size was six cm (range: 3 – 10 cm), and the median frame time ten months (range: 7 – 17 months). The EFI in the ASR group and the BT group measured 2.2 months/cm (range: 1.3 – 5.4 months/cm) and 1.9 months/cm (range: 0.8 – 2.8 months/cm), respectively. The comparison between the EFI of the ASL group and the BT group showed no statistically significant difference (p=0.147). Five patients of the ASR group (7 surgeries) and 19 patients of the BT group (23 surgeries) needed further unplanned surgery (p=0.001). Docking site surgery was significantly more frequent in BT; 66.7%, versus ASL; 5.3% (p=0.0001). Conclusion. Acute shortening/relengthening and bone transport are both safe and effective distraction osteogenesis techniques for the treatment of infected tibial non-unions. They share similar frame times per centimetre of defect. However, ASR demonstrated a statistically significant lower rate of unplanned surgeries

Background. The failure and subsequent withdrawal of the ASR device in both its resurfacing and THR form has been well documented. The National Joint Registry report of 2010 quoted figures of 12–13% failure at five years. Adverse reaction to metal debris (ARMD) is a poorly understood condition and patients developing severe metal reactions may go unrecognised for sometime. Patients and Methods. In 2004 a single surgeons prospective study of the ASR bearing surface was undertaken. We present the 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. 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. A second survival analysis was carried out with a failure defined as a serum cobalt > 7µg/L. Full explant analysis was carried out for retrieved prostheses. Results. There were 505 ASR patients in total. 657 metal ion samples were available at the time of writing (152 repeats). Survival analysis using revision/listed 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 prosthesis was 8.23mm. 3. /year (0.51–95.5). Conclusion. A number of design flaws in the ASR has led to excessive wear of the bearing & taper leading to catastrophic failure secondary to ARMD