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

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

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

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

The spine is one of the most common sites of bony metastasis, with 80% of prostate, lung, and breast cancers metastasizing to the vertebrae resulting in significant morbidity. Current treatment modalities are systemic chemotherapy, such as Doxorubicin (Dox), administered after resection to prevent cancer recurrence, and systemic antiresorptive medication, such as Zolendronate (Zol), to prevent tumor-induced bone destruction. The large systemic doses required to elicit an adequate effect in the spine often leads to significant side-effects by both drugs, limiting their prolonged use and effectiveness. Recently published work by our lab has shown that biocompatible 3D-printed porous polymer scaffolds are an effective way of delivering Dox locally over a sustained period while inhibiting tumor growth in vitro. Our lab has also generated promising results regarding antitumor properties of Zol in vitro. We aim to develop 3D-printed scaffolds to deliver a combination of Zol and Dox that can potentially allow for a synergistic antitumor activity while preventing concurrent bone loss locally at the site of a tumor, avoiding long systemic exposure to these drugs and decreasing side effects in the clinical setting.

The PORO Lay polymer filaments are 3D-printed into 5mm diameter disks, washed with deionized water and loaded with Dox or Zol in aqueous buffer over 7 days. Dox or Zol-containing supernatant was collected daily and the drug release was analyzed over time in a fluorescence plate reader. The polymer-drug (Dox or Zol) release was tested in vitro on prostate and lung cancer cell lines and on prostate- or lung-induced bone metastases cells. Alternatively, direct drug treatment was also carried out on the same cells in vitro. Following treatment, all cells were subject to proliferation assay (MTT and alamar blue), viability assay (LIVE/DEAD), migration assay (Boyden chamber) and invasion assay (3D gel matrix). 3D-printed scaffolds loaded with both Dox and Zol will also be tested on cells.

We have established an effective dose (EC50) for prostate and lung cancer cell lines and bone metastases cells with direct treatment with Zol or Dox. We have titrated the drug loading of scaffolds to allow for a release amount of Dox at the EC50 dose over 7 days. In ongoing experiments, we are testing the release of Zol. We have shown Dox releasing scaffolds inhibit cancer cell growth in a 2D culture over 7 days using the above cellular assays and testing the scaffolds with Zol is currently being analyzed.

3D-printed porous polymers like the PORO Lay series of products offer a novel and versatile opportunity for delivery of drugs in future clinical settings. They can decrease systemic exposure of drugs while at the same time concentrating the drugs effect at the site of tumors and consequently inhibit tumor proliferation. Their ability to be loaded with multiple drugs can allow for achieving multiple goals while taking advantage of synergistic effects of different drugs. The ability to 3D-print these polymers can allow for production of custom implants that offer better structural support for bone growth.

Hip resurfacing may be a useful surgical procedure when patient selection is correct and only implants with superior performance are used. In order to establish a body of evidence in relation to hip resurfacing, pseudotumour formation and its genetic predisposition, we performed a case-control study investigating the role of HLA genotype in the development of pseudotumour around MoM hip resurfacings. All metal-on-metal (MoM) hip resurfacings performed in the history of the institution were assessed. A total of 392 hip resurfacings were performed by 12 surgeons between February 1st 2005 and October 31st 2007. In all cases, pseudotumour was confirmed in the preoperative setting on Metal Artefact Reduction Sequencing (MARS) MRI. Controls were matched by implant (ASR or BHR) and absence of pseudotumour was confirmed on MRI. Blood samples from all cases and controls underwent genetic analysis using Next Generation Sequencing (NGS) assessing for the following alleles of 11 HLA loci (A, B, C, DRB1, DRB3/4/5, DQA1, DQB1, DPB1, DPA1). Statistical significance was determined using a Fisher's exact test or Chi-Squared test given the small sample size to quantify the clinical association between HLA genotype and the need for revision surgery due to pseudotumour. Both groups were matched for implant type (55% ASR, 45% BHR in both the case and control groups). According to the ALVAL histological classification described by Kurmis et al., the majority of cases (63%, n=10) were found to have group 2 histological findings. Four cases (25%) had group 3 histological findings and 2 (12%) patients had group 4 findings. Of the 11 HLA loci analysed, 2 were significantly associated with a higher risk of pseudotumour formation (DQB1*05:03:01 and DRB1*14:54:01) and 4 were noted to be protective against pseudotumour formation (DQA1*03:01:01, DRB1*04:04:01, C*01:02:01, B*27:05:02). These findings further develop the knowledge base around specific HLA genotypes and their role in the development of pseudotumour formation in MoM hip resurfacing. Specifically, the two alleles at higher risk of pseudotumour formation (DQB1*05:03:01 and DRB1*14:54:01) in MoM hip resurfacing should be noted, particularly as patient-specific genotype-dependent surgical treatments continue to develop in the future

Introduction. Complication and revision rates have shown to be high for all metal-on-metal (MoM) bearings, especially for the ASR Hip System (ASR hip resurfacing arthroplasty (HRA) and ASR XL total hip arthroplasty (THA)). This prompted the global recall of the ASR Hip System in 2010. Many studies have previously explored the association between female gender and revision surgery MoM HRA implants; yet less research has been dedicated to exploring this relationship in MoM THA. The first purpose of this study was to assess the associations between gender and implant survival, as well as adverse local tissue reaction (ALTR), in patients with MoM THA. Secondly, we sought to report the differences between genders in metal ion levels and patient reported outcome measures (PROMs) in patients with MoM THA. Methods. The study population consisted of 729 ASR XL THA patients (820 hips) enrolled from September 2012 to June 2015 in a multicenter follow-up study at a mean of 6.4 (3–11) years from index surgery. The mean age at the time of index surgery was 60 (22–95) years and 338 were women (46%). All patients enrolled had complete patient and surgical demographic information, blood metal ion levels and PROMs obtained within 6 months, and a valid AP pelvis radiograph dating a maximum of 2 years prior to consent. Blood metal ion levels and PROMs were then obtained annually after enrollment. A sub-set of patients from a single center had annual metal artifact reduction sequence (MARS) MRI performed and were analyzed for the presence of moderate-to-severe ALTR. Results. Eighty-nine hips (11%) were revised during the study period. Forty-five of the 338 men underwent revision (13%), and 44 of the 391 women underwent revision (11%). The mean time from index surgery to revision was 7 years for both males and females. After controlling for confounding variables, the only variables found to be associated with revision surgery in patients with unilateral THA were VAS pain (hazard ratio [HR], 1.28; p < 0.001) and elevated cobalt metal ion levels (HR, 1.02; p < 0.001). Patients with bilateral arthroplasties with low HHS (HR, 0.96; p < 0.001) and high cobalt levels (HR, 1.02; p < 0.001) were at increased risk for revision. Moderate-to-severe ALTRs were identified in 48 of the 133 hips with MARS MRI (36%), 17 of which were in females (30% of females) and 31 in males (40% of males). The only variables found to be associated with the presence of moderate-to-severe ALTR were abduction angle (HR, 0.92; p = 0.004) and Corail AMT stem type (HR, 2.31; p = 0.012). Female gender did not influence the risk of revision or ALTR. Chromium concentrations were greater in female patients than males, while cobalt levels were similar between genders. Males reported higher HHS, EQ-5D and UCLA scores than females. Discussion and Conclusion. Both males and females with MoM THA implants should be followed with equal vigilance as gender does not appear to be associated with poor outcomes, such as revision surgery and presence of ALTR

Introduction:. The ASR™ Articular Surface Replacement and ASR™ XL Metal-on-Metal systems were recalled due to high revision rates at five years. A worldwide clinical follow-up of patients was initiated. This paper summarizes current findings in South Africa (SA) in comparison with those outside SA (OSA). Methods:. Patients were followed annually, or until revision, from 10 clinical centers worldwide. Data collected includes demographic, surgical, radiographic, blood metal ion levels, and patient reported outcome measures (PROM). Results:. There were 715 (353 ASR/336 ASR-XL) hips enrolled in the study; 187 ASR and 32 ASR-XL from South Africa. The average time from index surgery was 6 years (2–10) for both SA and OSA. Since enrollment, 2.7% (19) hips were revised (none from SA) and of these 58% (11) had adverse local tissue reaction. Blood metal Co/Cr ion levels decreased by about 50% post-revision. There was no difference in average blood metal ion levels between patients in SA and OSA. Globally, the average blood cobalt ion level was higher for patients with ASR-XL than patients with ASR. The average cup abduction was 43.2° (20°–65°) with little difference between SA and OSA. The average EQ-5D index for SA patients was 0.93 vs. 0.82 for OSA. Discussion:. Currently, South Africa represented the majority of ASR surface replacement implants in the study, which were predominantly in males. This may have contributed to the higher PROM scores in SA compared to the OSA. While no revisions were reported from SA in this study so far, metal ion levels were lower after revision surgery

Introduction. It has been speculated that impact deformation of thin 1-piece cups used for modern metal-on-metal hip replacement may contribute to early failure. The purpose of this study was to reproduce typical impact deformation and quantify the effect of this on the frictional torque generated at the hip. Methods. We tested nine hip couples of three designs (the ASR, BHR and Durom) and three sizes (42mm, 46mm and 50mm). A custom compression device was designed to replicate the in vivo forces and impact deformation of 1-piece metal cups reported in the literature. Each cup was mounted in the device, which itself was mounted on a mechanical testing machine. The cups were compressed with incremental loads up to a maximum of 2000N. At each increment we measured cup deformation, and then the head component was seated into the cup. The hip was lubricated and the head component rotated 60 degrees axially within the cup and the axial torque was measured. Results. Maximum deformation occurred at the rim for all cups, and was not associated with cup diameter (p = 0.42). However, at all applied loads the BHR cups were deformed significantly less than both the ASR and Durom cups (all p < 0.05). We observed deformation that exceeded the diametric clearance for both the ASR and Durom. Deformation resulted in increased axial torque up to eight times higher than those measured at zero deformation. The maximum torques generated for the BHR cups were significantly lower than those observed for both the ASR and Durom cups. Discussion. Deformation of 1-piece cups, equatorial bearing and subsequent increased frictional torque is likely to have widespread consequences for the performance of metal-on-metal hip replacement. This may include loosening of the cup, mechanical damage at the taper junction and increased early wear of the bearing surface

Hip resurfacing offers an attractive alternative to conventional total hip arthroplasty in young active patients. It is particularly advantageous for bone preservation for future revisions. Articular Surface Replacement (ASR) is a hip resurfacing prosthesis manufactured by DePuy Orthopaedics Inc. (Warsaw, IN). The manufacturer voluntarily recalled the ASR system in 2010 after an increasing number of product failures. The present study aimed to determine the long-term results in a large cohort of patients who received the ASR prosthesis. Between February 2004 and August 2010, 592 consecutive hip resurfacings using the ASR (DePuy Orthopaedics Inc., Warsaw, IN) resurfacing implant were performed in 496 patients (391 males and 105 females). The mean age of the patients at the time of the surgery was 54 (range: 25 to 74) years. Osteoarthritis was the most common diagnosis in 575 hips (97.1%). The remaining patients (2.9%) developed secondary degenerative disease from ankylosing spondylitis, avascular necrosis, developmental hip dysplasia, and rheumatoid arthritis. Clinical and radiographic information was available for all patients at the last follow up. Cobalt (Co) and chromium (Cr) levels were measured in 265 patients (298 hips) by inductively coupled plasma-mass spectrometry (ICP-MS). The average follow up of the study was 8.6 years (range: 5.2 to 11.6 years). The mean Harris hip and UCLA scores significantly improved from 44 and 2 pre-operatively to 85.3 and 7.1 respectively. The median Co and Cr ion level was 3.81 microgram per liter and 2.15 microgram per liter respectively. Twenty-seven patients (5.4%) were found to have blood levels of both Co and Cr ions that were greater than 7 microgram per liter. Fifty-four patients (9.1%) were revised to a total hip arthroplasty. Kaplan-Meier survival analysis showed a survival rate of 87.1% at 8.6 years with revision for any cause and 87.9% if infection is removed. A significantly higher survival rate was observed for the male patients (90.2%, p <0.0001) and for the patients with ASRs with femoral heads diameters larger than 52 mm (90.1%, p=0.0003). This study confirms that patient selection criteria are of great importance to the overall survivorship of hip resurfacing arthroplasty. Improved clinical results have been reconfirmed with the use of larger diameter femoral heads

Introduction. Although good mid-term results have been reported with some metal on metal hip replacements, reported complications due to metal on metal (MOM) related reactions are a cause for concern. We have assessed the early clinical outcome and results of routine metal artefact reduction MRI findings in a consecutive series of patients with a modern large head metal on metal hip replacement. Methods. 62 ASR XL Corail total hip replacements (THR) and 17 ASR resurfacings were performed at our hospital between 2005 and 2008. All patients were reviewed and assessed with an Oxford hip score (OHS), a plain radiograph and a MRI imaging was obtained on 76 (96%) hips. Implant position was assessed using Wrightington cup orientation software. Results. At a mean follow-up of 32 months, 8 ASR XL Corail THRs had been revised. 6 revisions were performed for MRI-confirmed MOM-related pathology. Histology confirmed a MOM reaction in all 6 cases. Of the 76 hips that were MRI scanned, 27 (36%) had typical features of a MOM reaction. These were classified as mild in 5 (7%), moderate in 18 (24%) and severe in 4 (5%). 78 patients completed an OHS and the mean score was 21. The mean OHS was 37 pre-operatively in those that had been revised, 19 in patients with abnormal MRI findings and 23 in those with a normal MRI. 10 patients with abnormal MRIs had a near perfect OHS (15 or less). Conclusion. The ASR XL Corail THR has an unacceptably high early failure rate. MRI detected metal debris related soft tissue related reactions were very common and often asymptomatic. We recommend that patients with this implant should be closely followed up and undergo routine metal artefact reduction MRI screening

Background and aim. Since the market withdrawal of the ASR hip resurfacing in August 2010 because of a higher than expected revision rate as reported in the Australian Joint Replacement Registry (AOAJRR), metal-on-metal hip resurfacing arthroplasty (MoMHRA) has become a controversial procedure for hip replacement. Failures related to destructive adverse local tissue reactions to metal wear debris have further discredited MoMHRA. Longer term series from experienced resurfacing specialists however, demonstrated good outcomes with excellent 10-to-15-year survivorship in young and active men. These results have recently been confirmed for some MoMHRA designs in the AOAJRR. Besides, all hip replacement registries report significantly worse survivorship of total hip arthroplasty (THA) in patients under 50 compared to older ages. The aim of this study was to review MoMHRA survivorship from the national registries reporting on hip resurfacing and determine the risk factors for revision in the different registries. Methods. The latest annual reports from the AOAJRR, the National Joint Registry of England and Wales (NJR), the Swedish Hip Registry (SHR), the Finnish Arthroplasty Registry, the New Zealand Joint Registry and the Arthroplasty Registry of the Emilia-Romagna Region in Italy (RIPO) were reviewed for 10-year survivorship of MoMHRA in general and specific designs in particular. Other registries did not have enough hip resurfacing data or long term data yet. The survivorship data were compared to conventional THA in comparable age groups and determinants for success/failure such as gender, age, diagnosis, implant design and size and surgical experience were reviewed. Results. All registries showed a significant decline of the use of MoMHRA. The AOAJRR reported a cumulative revision rate of 9.5% (95%CI: 8.9–10.1%) at 10 years for all hip resurfacings. Female gender, developmental dysplasia and femoral head sizes <49mm were significant risk factors with revision rates twice as high for head sizes <49mm compared to >55mm. In males, cumulative revision rate for all MoMHRA was 6.6% at 10 years and 7.8% at 13years with no difference in the age groups. ASR had significantly higher revision rates (23.9% at 7 years) compared to other designs. The Adept and the Mitch had the lowest revision rates at 7 years (3.6%). Cumulative revision rates for 10,750 BHR (males and females pooled) were 5.0% at 7 years, 6.9% at 10years and 8.4% at 13 years. Cumulative revision rates of THA in patients <55 years was 6.0% at 10 years and 9.4% at 13 years. Similar survivorship results were found in the Finnish, Swedish, New Zealand and RIPO registry. In the SHR, 10-year survivorship of THA in patients <50 was only around 87%. In the NJR, cumulative revision rates for all MoMHRA pooled were much less favourable (13% at 10 years – 22% in patients<50) but the revision probability of ASR was 30.4% compared to 9.0% for BHR. Surgical experience was also identified as an important determinant of success/failure. Discussion. Registries are now confirming good 10-year survivorship of certain MoMHRA designs with excellent results in males. Risk factors for revision are female gender, small head size, dysplasia and certain implant designs

Introduction. Studies of metal-on-metal (MoM) hip resurfacing arthroplasty (HRA) have reported high complication and failure rates due to elevated metal ion levels. These rates were shown to be especially high for the Articular Surface Replacement (ASR) HRA, possibly due to its unique design. Associations between metal ion concentrations and various biological and mechanical factors have been reported. Component positioning as measured by acetabular inclination has been shown to be of especially strong consequence in metal ion production in ASR HRA patients, but few studies have evaluated acetabular anteversion as an independent variable. The primary objective of this study was to evaluate the associations between component orientation, quantified by acetabular inclination and anteversion, and blood metal ions. Secondly, we sought to report whether conventional safe zones apply to MoM HRA implants or if these implants require their own positioning standards. Methods. We conducted a multi-center, prospective study of 512 unilateral ASR HRA patients enrolled from September 2012 to June 2015. At time of enrollment our patients were a mean of 7 (3–11.5) years from surgery. The mean age at surgery was 56 years and 24% were female. All subjects had complete demographic and surgical information and blood metal ions. In addition, each patient had valid AP pelvis and shoot-though lateral radiographs read by 5 validated readers measuring acetabular abduction and anteversion, and femoral offset. A multivariate logistic regression was used with high cobalt or chromium (greater than or equal to 7ppb) as the dependent variable. The independent variables were: female gender, UCLA activity score, age at surgery, femoral head size, time from surgery, femoral offset, acetabular abduction, and acetabular anteversion. Results. The average acetabular inclination angle was found to be 44.7° (20.6°–64.5°), and the average anteversion angle was 24° (0.2°–55.3°) (Figure 1). After controlling for the possible confounding variables, the factors contributing to elevated metal ions (≥ 7 ppb) were found to be time from surgery (OR = 1.29, p = 0.011), high abduction angle (– 55°) (OR = 4.40, p = 0.001), low anteversion angle (0°–10°) (OR = 3.82, p = 0.001), and female gender (OR = 3.45, p = 0.001). Discussion and Conclusion. We found that blood metal ion levels are affected by both acetabular inclination and anteversion (Figure 2). Furthermore, we observed that there was a high degree of variation in the positioning of these implants, and we conclude that those with high inclination and/or low anteversion angle should be most vigilantly monitored

Hip simulator studies have shown reduced hip offset can cause microseparation and increased wear in hard-on-hard hip bearings. However this has not been analysed yet in vivo. We studied the effect of reduced hip offset on serum metal ion levels in patients with metal-on-metal (MoM) hip arthroplasty. From all patients who underwent unilateral MoM bearing hip arthroplasty between 2005 and 2009, 63 patients had complete clinical evaluation, measurement of serum chromium and cobalt ion levels as well as biomechanical measurements on pre- and post operative radiographs (cup inclination, head inclination, change in hip offset and change in hip length.). Ten arthroplasties were revised due to adverse metal reaction and six patients awaiting revision. 55% of ASR hips showed higher metal ions (>7 ppb) whereas only 15% of non-ASR hips had higher ion levels. Patients with reduced postoperative hip offset by more than 5 mm had significantly higher mean metal ion levels compared to the the rest of the hips (31.8 ppb vs. 7.4 ppb, p=0.002). On subgroup analysis this effect was present in non-ASR hips (18.7 ppb vs. 4.7 ppb, p=0.025) but was not significant in ASR hips (29.6 ppb vs. 16.3 ppb, p=0.347). Our study demonstrated significantly higher serum metal ion levels in patients who lost more than 5 mm hip offset after arthroplasty. Reduced soft tissue tension leading to microseparation of the articulation and edge loading is a theoretical explanation for this effect. This may be relevant in other hard bearings such as ceramic-on-ceramic as well

Introduction. Edge loading is a common wear mechanism in Metal-on-Metal (MOM) hip resurfacing and is associated with higher wear rates and the incidence of pseudotumour. The purpose of this study was to develop a method to investigate the contributions of patient, surgical and implant design variables on the risk of edge loading. Method. We created a mathematical model to calculate the distance from the head-cup contact patch to the rim of the cup and used this to investigate the effect of component position, specific design features and patient activity on the risk of edge loading. We then used this method to calculate the contact patch to rim distance (CPRD) for 160 patients having undergone revision of their MOM hip resurfacing in order to identify any possible associations. Results. We identified several variables that reduce the CPRD and increase the risk of edge loading, including; increased cup anteversion and inclination, activities involving increased hip flexion, reduced clearance, reduced hip diameter and reduced cup arc angle. We also determined the threshold cup orientation for edge loading for five resurfacing designs (Figure 1). In patients with failed MOM hip resurfacings, there was a significant correlation between CPRD and both component wear rates (Figure 2) and blood metal ion levels (all p < 0.005). The ASR was associated with increased wear, reduced CPRD, and increased prevalence of edge loading (all p < 0.05). Conclusions. Edge loading is common and difficult to avoid in MOM hip resurfacing. Whilst some designs, such as the ASR, are more susceptible to edge loading, all are unforgiving of suboptimal cup position. Furthermore, common activities involving flexion of the hip result in edge loading even in patients with a well-positioned cup