AIMS: To define and compare magnetic resonance imaging (MRI) findings of asymptomatic patients with metal-on-metal (MOM) and polyethylene-on-metal (POM) total hip replacements (THRs).MATERIALS AND METHODS: Twenty-two THRs in 20 asymptomatic patients (seven men, 13 women, mean age 68 years, range 47-86 years) with normal hip radiographs were included in the study. These comprised 10 POM and 12 MOM bearings. Each patient underwent MRI with metal artefact reduction sequences (MARS) at a mean time of 46 months (POM) and 70 months (MOM) after surgery. Two musculoskeletal radiologists independently read each MRI examination for fluid collections, soft-tissue masses, muscle atrophy, and bone marrow signal changes.RESULTS: A pre-MRI hip radiograph showed no significant differences from the postoperative radiograph regarding acetabular inclination, femoral stem angle, and stem mantle grade. There were eight periprosthetic collections (one POM, seven MOM). The majority of THRs had normal gluteal muscles. The ipsilateral piriformis and obturator internus muscles were more frequently abnormal in the MOM group. Overall, there were no significant differences in the number of abnormalities between the two types of bearings.CONCLUSION: A range of MRI abnormalities are present in normal asymptomatic THRs but the increased frequency of these associated with MOM THR suggest that some of these changes might represent subclinical disease. (C) 2011 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Metal-on-metal hip replacements are the subject of much current debate. There is some evidence that there may be a hypersensitivity reaction, specific to metal-on-metal total hip replacements (THRs), which is associated with early failure of these prostheses. It has to date only been described in total replacements and not in metal-on-metal hip resurfacing. We present the case of a 68-year-old man who underwent bilateral metal-on-metal hip resurfacing for osteoarthrosis. The patient presented 6 months after surgery with pain and lateral thigh swelling. Pre-operative ultrasound and MRI demonstrated findings similar to those described in early failing metal-on-metal THRs, as well as evidence of lymphoreticular spread of metal debris. The operative findings included extensive aseptic soft-tissue necrosis. Histology revealed necrosis and a dense perivascular lymphocytic infiltrate along with metal debris within sinus histiocytes. The surgical, radiological and histological findings are similar to soft-tissue reactions described in metal-on-metal THRs.

The rate and mode of early failure in 463 Birmingham hip resurfacings in a two-centre, multisurgeon series were examined. Of the 463 patients two have died and three were lost to follow-up. The mean radiological and clinical follow-up was for 43 months (6 to 90). We have revised 13 resurfacings (2.8%) including seven for pain, three for fracture, two for dislocation and another for sepsis. Of these, nine had macroscopic and histological evidence of metallosis. The survival at five years was 95.8% (95% confidence interval (CI) 94.1 to 96.8) for revision for all causes and 96.9% (95% CI 95.5 to 98.3) for metallosis. The rate of metallosis related revision was 3.1% at five years. Risk factors for metallosis were female gender, a small femoral component, a high abduction angle and obesity. We do not advocate the use of the Birmingham Hip resurfacing procedure in patients with these risk factors.

There has been controversy about the practice of mixing femoral and acetabular implants from different manufacturers in total hip replacement (THR). We studied the clinical outcomes of over 1500 patients in the Exeter Primary Outcomes Study (EPOS) who underwent primary THR with a cemented Exeter stem (Stryker) but with various acetabular components. This was a prospective non-randomised multicentre study. Patient reported hip scores (Oxford Hip Score (OHS)) were measured before operation and at 1 and 2 years post operatively. The choice of acetabular implant was at the surgeons’ discretion. 982 patients had reached four year follow up. Six types of acetabular component were examined (Exeter, Exeter Contemporary, Duraloc (all Stryker), Charnley (DePuy), Cenator (Corin), and Trilogy (Zimmer)).Patients who received a Charnley cup were found to have worse pre-operative status (significantly …

ObjectivesThe clinical importance of a leg length discrepancy (LLD) following total hip arthroplasty (THA) remains controversial. This study was undertaken to determine the effects of LLD on clinical outcomes at up to 3 years follow-up.Design and settingProspective, multicentre study.ParticipantsNine hundred and eighty-seven cases of primary THA, categorised into two main groups: the NoLLD group (LLD of less than 10mm) and the LLD group (LLD of 10mm or more).Main outcome measuresThe primary outcome measure was the change in Oxford Hip Score (ΔOHS) at up to 3 years follow-up. Secondary outcome measures were length of operating time and hospital stay, and revision and dislocation rates. Potential predisposing factors for LLD, including body mass index, age and type of anaesthesia employed, were examined.ResultsAt 3 years, the LLD group had a significantly worse ΔOHS [22.0; 95% confidence interval (CI) 20.5 to 23.5] compared with the NoLLD group (23.8; 95% CI 23.1 to 24.5) (P=0.034). There were no significant differences in revision (P=0.389) or dislocation (P=0.220) rates between the two groups. Use of an epidural was associated with a decreased incidence of developing an LLD of 10mm (P=0.004).ConclusionA postoperative LLD of 10mm or more leads to poorer functional outcomes. Further studies are needed to assess the impact of an LLD on clinical outcomes in the longer term.

The optimal surgical approach for total hip replacement (THR) remains controversial. We report the clinical outcomes of over 1000 patients in the Exeter primary outcomes study (epos) who underwent primary THR with a cemented Exeter stem (Stryker) but with various acetabular components. This was a prospective non randomised multi centre study. Patient reported hip scores (oxford hip score (OHS)) were measured before operation and at 3 months (n= 1312), 1 (n=1276), 2 (n= 1225), 3 (n=1205) and 4 (n=975) years post operatively. Physician reported scores (Merle d’Aubigne / Postel, MDAP) were measured before operation and at 12 months. All of the operations were carried out using either the anterolateral (Hardinge or modification) or posterior approach.The posterior approach gave better absolute OHS scores at 3 months and 1 year compared with the anterolateral approach. The improvement in OHS …

AIM: To perform a retrospective review of all the conventional radiographic and magnetic resonance imaging (MRI) studies performed in patients with early postoperative pain following cobalt-chrome metal-on-metal total hip arthroplasty.METHODS: A retrospective review of the radiology, surgical findings and histology in nineteen patients who had undergone a total of 20 hip arthroplasties using a cobalt-chromium on cobalt-chromium alloy prosthesis was undertaken.RESULTS: Measures of implant placement on the immediate postoperative radiographs were all within the normal ranges (n = 20). Where more than one postoperative radiograph was available statistical analysis revealed no evidence of progressive change before the MRI examination (14). The median postoperative time to MRI was 35 months (range 11-63 months). Abnormalities were demonstrated using MRI in all symptomatic hips (n = 20). These comprised: periprosthetic fluid collections (20), which were isointense to muscle on T1-weighted images in 19 cases and hyperintense on T2-weighted images in 18 cases, periprosthetic bone marrow oedema (n = 6), muscle oedema (n = 4), avulsion of the gluteus minimus and medius tendons (n = 5), atrophy of piriformis (n = 15) and obturator internus (n = 17), and fracture of the medial. calcar (n = 1). Operative findings in patients who had undergone revision surgery (n = 15) included: fluid-filled cavities (n = 11), soft tissue necrosis (n = 8), gluteal tendon avulsion (n = 5), proximal femoral, diaphyseal necrosis (n = 4), and pitting and corrosion of the femoral. stems (n = 8), which were, in all cases, firmly fixed to the cement mantle. Histology revealed viable tissue in six hips with necrosis (n = 12) and fibrin deposition (n = 15) being the predominate findings. Other findings included a perivascular lymphocytic infiltrate (n = 5), features of active inflammation (n = 4), and metallosis (n = 1).CONCLUSION: A significant number of patients with metal-on-metal hip replacements presented with early postoperative pain because of an abnormal soft-tissue reaction. MRI can demonstrate characteristic soft-tissue disease in these patients where conventional radiographs are frequently normal. (c) 2007 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

The UK Department of Health established the Healthcare-associated Infection (HAI) Surveillance Steering Group in 2000 to develop a strategy for implementing a national programme for HAI surveillance in National Health Service trusts. A subgroup of this committee examined the surveillance of surgical site infections following orthopaedic surgery. This group oversaw a pilot scheme that was set up in 12 hospitals around the UK to explore the feasibility of implementing a system of surveillance that engaged clinical staff in its operation, provided a process for continuous data collection and could be maintained as part of routine hospital operation over time. A minimum data set was established by the subgroup, and Centers for Disease Control and Prevention (CDC) definitions of infection were used. By March 2003, the surveillance had been undertaken continuously in 11 sites for one to two years, depending on the date of implementation. Only one hospital had ceased data collection. The information was collected mainly by clinical staff, with support and co-ordination usually provided by infection control teams. Data on more than 5400 procedures were available for analysis for four core procedures: arthroplasty of the hip and knee; hemi-arthroplasty of the hip; and internal fixation of trochanteric fractures of the femur. The data set permitted the calculation of risk-adjusted rates, allowing comparisons between hospitals and within a hospital over time. The methodology enhanced clinical ownership of the surveillance process, re-inforced infection control as the responsibility of all staff, and provided timely feedback and local data analysis. The use of CDC definitions permitted international comparisons of the data.