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

Background:. Higher than expected revision rates have been observed in large bearing metal-on-metal total hip replacements. We have introduced a metal on metal hip screening clinic at our unit and report the results. Methods:. All patients who had a metal-on-metal total hip replacement implanted at our unit were recalled to clinic. Screening consisted of clinical examination, Oxford hip score, radiographs, MARS MRI and serum cobalt/chromium ion levels. MRI scans were graded (Norwich Classification) by a single consultant radiologist who was blinded to the history, examination, and metal levels. Patients were sub-classified into 6 groups, which determined further follow up and were either entered into a regular screening programme or referred to a revision arthroplasty surgeon for a decision on whether revision was required. Results:. A total of 278 patients were identified. Four patients had moved away, 2 refused follow-up and 1 patient had died. This left 271 patients in our cohort, having 299 metal-on-metal hip replacements with a M:F ratio of 1.5:1 and a mean age of 61.9 years (29–87). 59 (21.8%) patients complained of a recent deterioration in symptoms. Sixty seven (24.7%) patients had an abnormal xray appearance of their hip replacement (inclination >50 degrees, loosening, or migration of prosthesis). Of the 232 hips which underwent MARS MRI, 118 (50.9%) were group A (normal appearance), 66 (28.4%) C1 (mild MOM disease), 31 (13.4%) C2 (moderate MOM disease), and 17 (7.3%) C3 (severe MOM disease). One hundred and seventeen (38.9%) had a substantial fluid collection around the hip. Serum cobalt/chromium metal ions were raised in 135 patients (49.5%), 46 of which had one (8.8%) or both (8%) above 7 ppb (chromium >134 nmol/L, cobalt > 119 nmol/L). One hundred and forty nine patients (55%) remained under review in the MOM clinic and 122 (45%, 148 hip replacements) were referred to a revision surgeon for specialist opinion. Of these 21 hips (14.2%) have been revised and a further 14 hips (9.5%) are awaiting revision. In total 64 hips (21.3% of all large head metal on metal hips implanted in our unit) have been revised with a further 22 (7.3%) listed for revision. Of these, 13 were histologically proven to be an ALVAL reaction, 19 had the classic clinical findings of ALVAL (but not histologically confirmed), and 1 was a non-specific reaction to metal wear. 53 patients (19.4%, 56 hips) were completely asymptomatic but had evidence of ALVAL soft tissue reaction on MRI and/or rising metal ion levels – 9 of these hips have already been revised for ALVAL and 6 more listed for revision. Conclusions. Our screening programme has identified 53 (19.6%) asymptomatic patients who have evidence of a suspicious reaction to their metal-on-metal hip replacements. 16 (3%) of these have gone on to revision. We would recommend all patients with a metal-on-metal total hip replacement in situ are fully screened for ARMD regardless of symptoms and metal ion levels

All patients with a MOM THR implanted at our unit were recalled for clinical examination, Oxford hip score, radiographs, MARS MRI and cobalt/chromium ion levels. Patients were sub-classified, determining further follow up: a regular screening programme or referral to a revision arthroplasty surgeon. We identified 299 MOM THR's. 59 patients reported a recent deterioration in symptoms. 67 had an abnormal x-ray. 232 hips underwent MARS MRI: 66 showed mild MOM disease, 31 moderate MOM disease, 17 severe MOM disease. 117 had a substantial fluid collection around the hip. Serum cobalt/chromium ions were raised in 135 patients. 46 had one or both above 7 ppb. 148 THR's were referred to a revision surgeon. 21 have been revised and 14 are awaiting revision. In total 64 hips have been revised. 13 were histologically proven ALVAL, 19 had clinical findings of ALVAL (not histologically confirmed), and 1 non-specific reaction to metal wear. 53 asymptomatic patients had evidence of soft tissue reaction on MRI and/or rising metal ions. Our screening programme identified asymptomatic patients with evidence of a suspicious reaction to their MOM THR. We recommend all patients with a MOM THR are fully screened for ARMD regardless of symptoms and metal ion levels

Young osteoarthritic male patients have been considered the ideal candidates for Metal-on-Metal (MoM) hip resurfacing arthroplasty (HRA), based on generally good long term results. In contrast, hip resurfacing in young female patients has become controversial. Recently, one implant manufacturer withdrew 46mm and smaller components, citing poorer than expected 10 year outcomes in females with smaller HRAs. Whether this difference is related to gender or to component size is still debated. Possible reasons for higher failure rates reported in females include higher rates of hip dysplasia, poorer bone quality and the risk of higher wear in some smaller sized implants with low cup coverage angles. We reviewed HRA revision specimens with the aim of comparing mode of failure, time to revision, femoral cement characteristics and acetabular bone attachment in specimens larger and smaller than 46mm and from male versus female patients. Methods. The study included all of the MoM HRA devices in our collection. Of the 284 hip resurfacing devices with complete clinical information, 131 were from male and 153 from female patients. Femoral sizes ranged from 36 – 58mm, median and mode 46mm; median size in females was 44 and 50mm in males. Time to failure ranged from 1 to 178 months, median 24 mos. Seven designs were represented but the majority were Conserve Plus (n=105 WMT, USA) and BHR (n=78 Smith & Nephew, USA) which differ in cementing technique. 131 femoral components were sectioned and the width of the cement mantle and the amount of cement in the head were measured. Where available, the amount of bone attached to the cup porous surface (n=91), tissue ALVAL scores (n=75) and bearing wear depth (n=138) were included in the multivariate analysis. Results. As a function of gender, there were no significant differences in time to revision, cement measurements or ALVAL scores. Wear depth was significantly higher in females (femoral 41um vs 21um; cup 50um vs 16um, p=0.05). As a function of size (46 and less = small), the <46mm group had a slightly shorter time to revision, 30 vs 38 months, p=0.04). Bone ingrowth ranged from 0 to 60% (Figure 1) and significantly less bone attachment was noted in both the smaller and larger components (p = 0.001). Other characteristics were similar in both groups. When wear-related failure modes (cup malposition, lysis, high ions) were compared, no differences between male and female or large vs small were found. The amount of cement in the femoral heads covered a wide range but femoral loosening or fracture rates were not different as a function of size or gender. Conclusion. This review of 248 revised HRAs from multiple surgeons, designs and modes of failure found no clear evidence that smaller HRA components were at higher risk of earlier failure or for any particular failure mode. The small components in this cohort were not more likely to have wear-related failures but of note, very few of these HRAs had implants with low coverage angles in the small sizes

The histopathology of periprosthetic tissues has been important to understanding the relationship between wear debris and arthroplasty outcome. In a landmark 1977paper, Willert and Semlitsch (1) used a semiquantitative rating to show that tissue reactions largely reflected the extent of particulate debris. Notably, small amounts of debris, including metal, could be eliminated without “overstraining the tissues” but excess debris led to deleterious changes. Currently, a plethora of terms is used to describe tissues from metal-on-metal (M-M) hips and corroded modular connections. We reviewed the evaluation and reporting of local tissue reactions over time, and asked if a dose response has been found between metal and tissue features, and how the use of more standardized terms and quantitative methodologies could reduce the current confusion in terminology. Methods. The PubMed database was searchedbetween 2000 and 2015 for papers using “metal sensitivity /allergy /hypersensitivity, Adverse Local Tissue Reaction (ALTR): osteolysis, metallosis, lymphocytic infiltration, Aseptic Lymphocytic Vasculitis-Associated Lesions (ALVAL), Adverse Reaction to Metal Debris (ARMD) or pseudotumor/ pseudotumour” as well as metal-on-metal / metal-metal AND hip arthroplasty/replacement. Reports lacking soft tissue histological analysis were excluded. Results. 131 articles describing M-M tissue histology were found. In earlier studies, the terms metal sensitivity / hypersensitivity /allergy implied or stated the potential for a Type IV delayed type hypersensitivity response as a reason for revision. More recently those terms have largely been replaced by broader terms such as ALTR, ALVAL and ARMD. ALVAL and metal hypersensitivity were often used interchangeably, both as failure modes and histological findings. Several histology scoring systems have been published but were only used in a limited number of studies. Correlations of histological features with metal levels or component wear were inconclusive, typically because of a high degree of variability. Interestingly, there were very few descriptions that concluded that the observed reactions were benign / normal or anticipated i.e. regardless of the histological features, extent of debris or failure mode, the histology was interpreted as showing an adverse reaction. Discussion. There is now an expanded set of terms to describe tissues but they lack clear definitions and typically do not use quantitative histological data to describe a wide range of periprosthetic reactions to metal. Lower limits of inflammation, necrosis or re-organization that represent a “normal” reaction to surgery and/or small amounts of wear debris are not clearly defined and are rarely discussed. The widespread adoption of the term “adverse” in the present tissue lexicon implies a cause and effect relationship between metal wear and corrosion products and histological features even though this has yet to be determined. The use of quantitative histological scores rather than subjective histological descriptions is imperative to improve the understanding and reporting of the range of periprosthetic reactions. In particular, a new lexicon that allows for a level of tissue reaction that is not misinterpreted as adverse is required

Introduction. Little is known about the relationship between head-neck corrosion and its effect on periprosthetic tissues and distant organs in the majority of patients hosting apparently well-functioning devices. We studied the degree and type of taper damage and the histopathologic response in periprosthetic tissue and distant organs. Methods. A total of 50 contemporary THRs (34 primary, 16 revision) retrieved postmortem from 40 patients after 0.4–26 years were studied. Forty-three femoral stems were CoCrMo and 7 were Ti6Al4V. In every case, a CoCrMo-alloy head articulated against a cementless polyethylene cup (19 XLPE and 31 UHMWPE). H&E and IHC sections of the joint pseudocapsules and liver were graded 1–4 for the intensity of various inflammatory cell infiltrates and tissue necrosis. The nature of the tissue response in the joint capsule, liver, spleen, kidneys and lymph nodes was assessed. Wear and corrosion products in the tissues were identified using SEM and EDS. Taper surfaces were graded for corrosion damage using modified Goldberg scoring and examined by SEM to determine the acting corrosion mode. Correlations between damage scores and the histologic variables were generated using the Spearman test. Results. No correlation was seen between taper damage scores and the macrophage response in the joint pseudocapsule. The distribution of corrosion scores for heads and femoral trunnions is shown in Figure 1. Moderate or severe corrosion of the head and/or trunnion was present in 9 hips (8 CoCr/CoCr and 1 CoCr/TiAlV). One patient with bilateral hips had local ALVAL-like lymphocyte-dominated tissue reactions (Figure 2) and mild focal lymphocytic infiltrates in the liver and kidneys (Figure 3). This was associated with severe intergranular corrosion of the CoCrMo trunnion and column damage on the head taper. Particle-laden macrophages in pseudocapsules were significantly correlated with liver macrophages (r=.382, p=0.012) and liver lymphocytes (r=.367, p=0.013). Pseudocapsule macrophage responses to metallic and/or polyethylene wear particles ranged widely from minimal to marked. Focal tissue necrosis was related to high concentrations of particulate wear debris. A minimal number of metallic particle-laden macrophages were also detected in the liver and spleen; and macrophage granulomas were present in para-aortic lymph nodes, especially in revision cases. DISCUSSION. The generation of metal ions and particulates at corroded CoCrMo heads and CoCrMo or Ti6Al4V trunnions was a significant contributor to the presence of perivascular lymphocytes within the joint pseudocapsule, with 1 patient showing a histologic pattern consistent with ALVAL. Patient factors and the rate of corrosion are among variables influencing whether an ALVAL-type reaction will develop and whether or not it will become symptomatic. Macrophages in the joint pseudocapsules were positively correlated with inflammatory cells in the liver. In this study, the intensity of inflammatory infiltrates in distant organs was mild. However, several cases of organ dysfunction have been reported in association with catastrophic wear of CoCrMo components. It continues to be essential to minimize the generation of metal ions and particulates and to improve strategies for identifying and managing patients exposed to high levels of degradation products. For any figures or tables, please contact the authors directly

Increased modularity of total hip arthroplasty components has occurred, with theoretical advantages and disadvantages. Recent literature indicates the potential for elevated revision rates of modular neck systems and the potential for metallosis and ALVAL (Aseptic Lymphocyte dominated Vasculitis Associated Lesion) formation at the modular neck/stem site. Retrieval analysis of one modular neck implant design including SEM (Scanning Electron Microscopy) assessment was done and correlated to FEA (Finite Element Analysis) as well as clinical features of patient demographics, implant and laboratory analysis. Correlation of the consistent corrosion locations to FEA indicates that the material and design features of this system may result in a biomechanical reason for failure. The stem aspect of the modular neck/stem junction may be at particular risk

The dual mobility (DM) bearing concept was introduced to reduce the risk of dislocation in total hip arthroplasty (THA). Our aim was to evaluate the early outcomes following the utilisation of DM in primary and revision THA in our unit. Prospectively collected data on all patients undergoing a DM bearing at was reviewed between July 2012and December 2015. The primary outcome assessed was dislocation, with a secondary outcome revision for any reasons. All data was gathered from patient clinical records and the digital picture archiving and communication system (PACS). 30 primary THA were undertaken and 54 revision THAin the time period described. 11 of the procedures involved a proximal femoral endoprosthesis. The mean age in the primary setting was 65 and 73 in the revision population. The main indications for using DM bearing in the primary setting were; trauma (40%), residual dysplasia (40%) and malignancy (17%). There were no dislocations in the primary THA category. Indications in the revision THA cohort included 33% for aseptic loosening, 11% for instability, 18% for ALVAL reactions, 20% for infection, 18% for fracture. 1 out of the 54 revision THA had one large bearing dislocation requiring closed reduction. Subsequent analysis confirmed that implant alignment was satisfactory and this was a patient compliance issue due to mental health concerns. To date no patient in either cohort required revision surgery. Overall dislocation rate was 1.2%. Our early experience with DM bearings has been positive with no evidence of early failure or loosening. The dislocation rate overall has been low and matches the current large series in the literature

We retrospectively reviewed the mid term outcome of 88 MoM THA in 84 patients and 21Hip Resurfacing using Recap Magnum bearing surface performed during 2006 – 2009. There were 41 males and 47 females in the THA group and 17 males and 4 females in the Hip Resurfacing group. All procedures were performed through a posterior approach. The average head size for the THR group was 46mm and the cup size was 52mm and the average head size for the resurfacing was 50mm and cup size was 56mm respectively. Median age for the THA group was 60 yrs. (28–73) and for the Resurfacing it was 51.5 yrs. (32–62). Average follow up was 76 months for the THA group and 78 months for the Resurfacing group. Average serum cobalt for the THA and the Resurfacing groups were 53.2nmol/l (119) and 30.85 and the Chromium levels were 82.44nmol/l(134.5) and 67.49 respectively. Eight MRI scans showed abnormal fluid collections suspicious of ARMD in the THA group and 2 showed fluid collection in the Resurfacing group. There were five revisions in the THA group with the tissue diagnosis of ALVAL. In all except one case a well fixed uncemented stem (Taperloc) was retained. In our series Recap Magnum on a Taperloc stem showed 94% survival at five years and therefore we continue to review the cases annually with serum cobalt chromium levels and MRI scans

Purpose of the study. We reviewed one hundred and twenty patients who had primary total hip replacement using Corail/Pinnacle Metal on metal bearing surfaces between 2006 and 2009. We were interested in the metal ion levels of the whole cohort, the incidence of unexplained pain, pseudo tumour lesions (ALVAL) and early loosening and failure. We were particularly interested in the relationship of the acetabular cup position in relation to the pelvis and lumbar spine. Material and methods. We reviewed 120 charts and 104 patients in total. All patients had metal ion assays (cobalt and chromium). All patients had standardised radiographic evaluation using a special technique to assess acetabular cup position and the relationship to the pelvis and lumbar spine. Results. Ten patients had mild hip pain. This was not considered to be pathological pain related to the MOM articulation. None of the patients had any generalised symptoms of metal allergy as reported in the literature. We detected one patient with soft tissue fluid collections suggestive of an ALVAL lesion on ultrasound. The average cup inclination was 48 degrees with a range from 34 to 53 degrees. Conclusion. Our experience at 5 years with the Corail/Pinnacle Metal on Metal articulation has been acceptable. NO DISCLOSURES

Pain following total hip arthroplasty is a relatively rare event. Several series place the incidence of some degree of pain post THA at approximately 5%. A systematic approach to determining etiology will direct treatment. Hip pain can be categorised as:. Extrinsic to the Hip. –. Spine +/− radiculopathy. –. Vascular disease. –. Metabolic (Paget's). –. Malignancy. Intrinsic to the Hip. Intracapsular/Implant. Loosening. Sepsis. Prosthetic failure. Osteolysis. Instability. Thigh pain. Stem tip pain. Hypersensitivity/ALVAL. Extracapsular. Iliopsoas tendonitis. Snapping Hip. Trochanter problems (bursitis). Heterotopic ossification. A full history and appropriate physical exam will direct the clinician. The use of routine radiographs, blood tests, and special tests (i.e., blood metal ions, advanced imaging techniques) will be discussed I detail

Metal Bearings in Hip Arthroplasty – What Have We Learned?. Large metal on metal bearings have come back to hip arthroplasty the past five to ten years with great promise to minimize wear debris, eliminate osteolysis, reduce dislocations and improve range of motion. While some of these claims have proven to be true, new problems have surfaced that threaten the success of these devices. Metalosis, “pseudotumours” and ALVAL (aseptic lymphocytic vasculitis associated lesions) are appearing. These lesions produce pain that is difficult to confirm on routine exam and xray but eventually lead to early revision surgery. This paper will examine the advantages and complications of this hard bearing surface with a special look at complications, their prevention and management

Hip resurfacing using metal-on-metal bearings has a number of purported advantages over traditional total hip replacement in the young, active patient. Males in particular can benefit from the bone preservation, stability, and higher activity levels seen with this procedure. As more is learned about the factors affecting long-term outcome of hip resurfacing, component position has emerged as one major predictor of success. Given a well-selected patient, and a well-designed device, acetabular positioning is perhaps the most important determinant of long-term survivorship in hip resurfacing. One feature of resurfacing socket design which has not been widely disseminated is the sub-hemispheric arc of the bearing surface. While the outer circumference of the socket represents a complete hemisphere, and radiographic evaluation may assume that the apparent socket angle is satisfactory, the actual bearing is less than a hemisphere, so that the true abduction of the bearing is considerably more vertical. This important fact leads to excessive bearing inclination, edge loading, and all that follows, including runaway wear, metallosis, ALVAL, and pseudotumors. Inadequate socket anteversion can expose the psoas tendon to abrasion and tendonitis. Too much acetabular anteversion, especially when combined with increased femoral neck anteversion, can result in an overall decrease in bearing contact area, and excessive wear. Femoral component positioning is critical in the prevention of femoral neck fractures, which are a chief cause of early failure. Varus placement increases the tensile stresses on the superior femoral neck. Excessive valgus threatens notching. Both increase femoral neck fractures. Sufficient malposition will ultimately result in edge loading. Edge wear is incompatible with fluid film lubrication, the key to longevity of these bearings

Numerous studies have shown highly cross-linked polyethylene (XLPE) to be an extremely low wear bearing surface for total hip arthroplasty (THA) at intermediate term follow-up. Wear rates and the incidence of osteolysis for CoCr femoral heads on XLPE liners appears to be considerably less than what is observed for conventional polyethylene (PE). This has been demonstrated even in younger, more active patients. Nevertheless, polyethylene wear and associated osteolysis are still a concern, since the indications for THA have been expanded to include younger and more active patients. Both wear simulator and clinical data suggest that ceramic femoral heads can reduce bearing surface wear of conventional PE. There is, however, extremely limited evidence supporting any advantage of ceramic femoral heads over CoCr femoral heads with regards to bearing surface wear of XLPE. This is perhaps due to the relative difficulty in measuring the low wear rates of XLPE bearings in general, regardless of material composition of the femoral head. Although ceramic femoral heads are more scratch resistant and less susceptible to third body wear, their current clinical use to reduce wear of XLPE bearings is, in reality, based on the unproven assumption that use of ceramic femoral heads will have a similar effect on wear reduction as is seen with ceramic on conventional PE bearing couples. Nevertheless, the use of ceramic femoral heads has become common in younger, more active patients. Recently, corrosion at the head neck junction of modular THA (trunnionosis), has been determined to be the possible source of metal debris and metal ions associated with adverse local tissue reactions (ALTR or ARMD) in THA, including ALVAL and pseudotumors. There is general agreement that trunnionosis results from mechanically assisted crevice corrosion (fretting) of the modular junctions common to nearly all contemporary THA designs. Several design, material and patient factors have been implicated as contributors to this problem including larger diameter femoral heads (>36 mm), reduced femoral neck and taper geometry, flexural rigidity of the taper, and patient body weight and activity level. Data from our multicenter implant retrieval program has shown that corrosion at the head-neck junction of contemporary modular THAs may be reduced with use of ceramic femoral heads. The use of ceramic femoral heads also eliminates the potential for release of cobalt and chromium ions from the taper junctions of titanium alloy stems. In younger patients, the long term effects of cobalt ions released from corrosion at the modular neck junction are still unknown. Although the surgeon's selection of a ceramic femoral head in combination with a XLPE acetabular liner is likely based on the desire to minimise PE wear, the impact of femoral head composition on taper neck corrosion and ALTR is perhaps more of a concern in 2015. Until the problem of taper neck corrosion is more thoroughly understood and effectively addressed by implant manufacturers, the use of ceramic femoral heads in THA should be considered in the younger or more active patient. The increased cost of ceramic femoral heads creates a dilemma in defining who is “young” enough and “active” enough to be considered an appropriate candidate for a ceramic femoral head in our current environment of bundled care payments, value based purchasing and concern about providing cost-effective health care to our patients

As part of a prospective RSA study into a new design of short-stem, trabecular metal, Co-Cr femoral components with modular necks and . metal on polyethylene articulation. , three patients presented with almost identical symptoms of pain and a large avascular mass within the operated hip. All three cases came to exploration and similar findings of a solid pseudotumour within the hip joint were found in all thee cases. Infection was not present. All cases were submitted to histology and reviewed by a pathologist with specific interest in tissue reactions to foreign materials. All three cases showed histological features classical of published descriptions of ALVAL (Aseptic Lymphocyte-dominated Vasculitis Associated Lesion). A consistent finding was fretting corrosion of the neck-stem junction. These cases demonstrate that Co and Cr ions can provoke adverse tissue reactions even in the absence of metal/metal articulations. This has design implications for all modular Co-Cr necks. The stem used in this study has been voluntarily withdrawn from the Australian market but is still being implanted in Europe. We make recommendations that modular trunnion-style Co-Cr necks not be used and alternative materials and design solutions be sought

Introduction. Metal on metal hip arthroplasty continues to be controversial. Emerging evidence suggests that there are multiple modes of failure, and that the results of revision surgery are influenced by host and implant factors. Methods. This study compares a single surgeon series of hip resurfacings (Birmingham Hip Resurfacing {BHR}) and large diameter metal on metal total hip replacements (LDMOMTHR). Primary outcome measures included survival rates, failure secondary to histologically identified Adverse Reaction to Metal Debris (ARMD), and patient reported outcome measures (Oxford Hip Score {OHS}) following revision. Between 1999 and 2005, 458 BHR and 175 LDMOMTHR were performed. At latest review 43 BHR's (9.4%) and 28 LDMOMTHR's (14%) have been revised. Results. Failure secondary to ARMD was significantly greater in LDMOMTHR compared to BHR failures (89% and 16% respectively). Histology demonstrated a higher Aseptic Lymphocytic Vascular and Associated Lesions (ALVAL) score in the LDMOMTHR failures than the BHR failures (8.6 LDMOMTHR, 6.3 BHR). Patient reported outcomes were better following revision for failed BHR compared to LDMOMTHR. There was no difference between the revision cohorts for cup inclination, metal ion levels and gender. Failure of the BHR has predominantly been due to those causes unique to resurfacing such as avascular necrosis and fracture. In our series, aggressive ALVAL was unusual and clinical outcome following revision was superior compared to LDMOMTHR failures. The likely mechanisms that are responsible for the differences in outcome and the clinical implications will be discussed

The metal-on-metal total hip resurfacing arthroplasty is a good solution for the younger patient with osteoarthritis of the hip. It is effective in pain resolution and provides a good function. Our study of 300 BHR arthroplasties with a follow-up of 2 to 7 year shows good results in a young and active population. With an overall survival of 96.7% we obtained similar results to those of the design centre. The overall postoperative HHS score of 95.78 +/− 12.63 is in line with other studies. We noticed a similar increase in HHS in female patients and male patients. Even in the HOOS scores there was no significant difference between both groups. This is an important finding for the surgeon as well as the patients. Looking at the VAS scores for satisfaction or reoperation we could state that the high expectations of this population have been fulfilled. With have an acceptable revision rate of 2.42% the patients undergoing a revision were of a simular mean age than those in the overall group. Five of them are female, two are male. Since there were twice as many female as male patients there is little difference in revision percentage between both groups. There was 1 patient with a bilateral revision because of ALVAL (aseptic lymphocytic vasculitis associated lesion). Although femoral neck fractures are a known complication, there where none in our series. Patients are able to lead an active life and perform sports. The postoperative benefits are equal in men and women. The satisfaction rate confirms that we are able to meet the expectations in this high demand group

Introduction. We conducted independent wear analysis of retrieved metal on metal (MoM) hip components from around the world. All patients with resurfaced hips who developed adverse reactions to metal debris (ARMD) were found to have increased wear of the bearing surfaces. This was untrue in patients with large diameter (?36mm) MoM total hip replacements. This led us to search for other factors leading to ARMD. Methods. MoM THR explants retrieved from 78 patients suffering ARMD underwent full volumetric wear analysis of bearing surface and taper-junctions using coordinate measuring machine. Scanning electron microscopy (SEM) used to characterise material composition of specific areas. Results. 34 MoM THRs were found to have relatively low bearing surface wear (< 3mm. 3. /year). In each of these cases, material loss up to 60 microns wear depth was identified on the internal taper-junctions of femoral components. However, volumetric loss was rarely >5mm. 3. Similarly only 65% of metal ion levels of these patients were found to be greater than the MHRA guidance figure (7µg/L). Patterns of material loss at the tapers were consistent with antero-posterior force splaying open the taper-junction. This characteristic pattern was identified in number of commercially available devices (titanium and cobalt chromium stems). Soft tissue lesions were severe in patients found to have taper damage. Histology confirmed severe ALVAL with lymphoid neogenesis in majority cases, suggesting that wear debris from taper junctions may have greater potential to stimulate adverse immune response. Discussion. The results suggest that forces transmitted from large diameter hard-on-hard bearing surfaces are sufficient to cause mechanical damage to modular junctions with secondary localised corrosion. We urge caution in the use of these designs and recommend a re-evaluation of the stem head interface

Background. Previous studies have suggested that the modular junction of metal on metal (MoM) total hip replacements (THR) is an important source of metallic debris. Methods. We carried out a prospective study using custom techniques to analyse one of the largest collections of failed contemporary MoM devices in the world. All explants from patients who had suffered adverse reactions to metal debris (ARMD) were included in this study. These explants included: 82 36mm THRs, and 147 resurfacing head THRs and 140 resurfacing arthroplasties from several manufactures. Volumetric wear analysis of the bearing surfaces and taper junctions was carried out using a coordinate measuring machine. The relationships between total metallic loss and metal ion concentrations and the macroscopic and histological tissue appearance of THR patients were compared to those in resurfacing patients. Mann Whitney test for non-parametric data was used to assess significant differences between groups. Results. Resurfacing explants retrieved from patients who had suffered ARMD were found to have significantly higher median rates of volumetric wear than the THRs (10.16 versus 2.25mm. 3. /yr (p < 0.001)). Total volumetric material loss from taper junctions ranged from 0.01 to 21.55mm. 3. When volumetric taper wear was combined with bearing surface wear in the THR patients this total rate of material loss was still significantly less than in the resurfacing patients 2.52 versus 10.16mm. 3. /yr (p < 0.001)). Despite this, macroscopic tissue destruction and extent of ALVAL infiltration was found to be significantly greater in the THR patients. Conclusion. Taper debris appears to more readily stimulate a destructive immune cascade than debris from primary bearing surfaces. This cascade can culminate in catastrophic tissue necrosis when blood metal ion concentrations appear normal. MHRA guidance should distinguish clearly between MOM THRs and resurfacings

A multitude of different bearing combinations exist to recreate the artificial hip joint. To date, there is no particular ‘gold-standard’ total hip arthroplasty (THA) couple since none is faultless. Strategies to improve performance are aimed either at modifying the shape and design of components or their material properties. Wear particle generation is now well recognised as a cause of aseptic loosening which consistently features amongst the most common indication for revision THA and thus minimising wear lies at the cornerstone of developing bearing couples. However, history has shown the use of supposed newer and improved materials have not been without occasional catastrophic failure. Hard-on-hard bearings are theoretically more resistant to wear but component fracture and squeaking has been witnessed with ceramic-on-ceramic articulations whilst metal-on-metal articulations have been plagued by reports of pseudotumor and ALVAL formation. This has all led to resurgence in the hard-on-soft couple. More recently, corrosion at taper junctions has been identified as a significant factor in hip arthroplasty failure. Femoral head materials, surface changes or coatings may therefore have an increasing role to play. In 2005, a multi-center, prospective, assessor and patient-blinded, randomised control trial was initiated. This was designed as a three armed study with either cobalt-chrome or oxidized zirconium femoral heads articulating against highly cross-linked polyethylene (XLPE) liners and oxidized zirconium articulating against ultra-high molecular weight polyethylene (UHMWPE). Early reports that XLPE was significantly superior to UHMWPE when coupled with cobalt-chrome meant no patient involved in the study was approved to receive a couple of cobalt-chrome and UHMWPE since it was deemed to be a high wear group. We hypothesised that oxidized zirconium femoral heads would produce less linear wear than cobalt- chrome femoral heads at mid-term evaluation, whilst maintain similar outcomes when recording WOMAC, SF-36 and pain scores, and complication rates. All three groups were statistically comparable preoperatively and at five years when measuring normalised WOMAC, SF-36 and pain scale scores; all groups showed a statistically significant improvement in scores from baseline compared to at five years (p<0.001). There was no significant difference in mean femoral head penetration when either oxidized zirconium or cobalt-chrome where articulated with XLPE (p=0.1533) but a significant difference in mean femoral head penetration was observed between the group that had used UHMWPE and both the other groups which had used XLPE (p<0.001). There were no hips in which either acetabular or femoral osteolysis was observed. We have demonstrated that oxidized zirconium femoral heads are safe with low rates of wear when coupled with XLPE. However at five year follow-up, it appears that the choice of material of the acetabular bearing is more important than the choice of femoral head bearing. Further follow-up is needed in order to see if femoral head choice leads to a difference in outcome beyond 5 years as laboratory data suggests. Moreover the potential reduction of corrosion with ceramic or oxidized zirconium heads may yet also prove to be significant. It is likely that current and future data will lead us away from the use cobalt chrome heads towards alternatives that are less likely to be associated with corrosion or wear and osteolysis