Early failure of the Ultima metal-on-metal total hip replacement in the presence of normal plain radiographs.

Metal-on-metal total hip replacement has been targeted at younger patients with anticipated long-term survival, but the effect of the production of metal ions is a concern because of their possible toxicity to cells. We have reviewed the results of the use of the Ultima hybrid metal-on-metal total hip replacement, with a cemented polished tapered femoral component with a 28 mm diameter and a cobalt-chrome (CoCr) modular head, articulating with a 28 mm CoCr acetabular bearing surface secured in a titanium alloy uncemented shell. Between 1997 and 2004, 545 patients with 652 affected hips underwent replacement using this system. Up to 31 January 2008, 90 (13.8%) hips in 82 patients had been revised. Pain was the sole reason for revision in 44 hips (48.9%) of which 35 had normal plain radiographs. Peri-prosthetic fractures occurred in 17 hips (18.9%) with early dislocation in three (3.3%) and late dislocation in 16 (17.8%). Infection was found in nine hips (10.0%). At operation, a range of changes was noted including cavities containing cloudy fluid under pressure, necrotic soft tissues with avulsed tendons and denuded osteonecrotic upper femora. Corrosion was frequently observed on the retrieved cemented part of the femoral component. Typically, the peri-operative findings confirmed those found on pre-operative metal artefact reduction sequence MRI and histological examination showed severe necrosis. Metal artefact reduction sequence MRI proved to be useful when investigating these patients with pain in the absence of adverse plain radiological features.

Early clinical failure of the Birmingham metal-on-metal hip resurfacing is associated with metallosis and soft-tissue necrosis.

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.

The continued value of clinical and radiological surveillance: the Charnley Elite Plus hip replacement system at 12 years.

We report the follow-up at 12 years of the use of the Elite Plus total hip replacement (THR). We have previously reported the results at a mean of 6.4 years. Of the 217 patients (234 THRs), 83 had died and nine had been lost to follow-up. The patients were reviewed radiologically and clinically using the Oxford hip score. Of the 234 THRs, 19 (8.1%) had required a revision by the final follow-up in all but one for aseptic loosening. Survivorship analysis for revision showed a survival of 93.9% (95% confidence interval (CI) 89.2 to 96.5) at ten years, and of 88.0% (95% CI 81.8 to 92.3) at 12 years. At the final follow-up survival analysis showed that 37% (95% CI 37.3 to 44.7) of the prostheses had either failed radiologically or had been revised. Patients with a radiologically loose femoral component had a significantly poorer Oxford hip score than those with a well-fixed component (p = 0.03). Radiological loosening at 6.4 years was predictive of failure at 12 years. Medium-term radiographs and clinical scores should be included in the surveillance of THR to give an early indication of the performance of specific implants.

Early failure of a Birmingham resurfacing hip replacement with lymphoreticular spread of metal debris: pre-operative diagnosis with MR.

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.

MRI of early symptomatic metal-on-metal total hip arthroplasty: a retrospective review of radiological findings in 20 hips.

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.

The Elite Plus total hip arthroplasty: the need for radiological surveillance.

We prospectively studied 217 patients who underwent 234 Elite Plus total hip arthroplasties. At a mean of 6.4 (SD 0.7) years post-operatively, 39 patients had died and 22 were either lost to follow-up or had no radiographs available. Clinical (Oxford hip score) and radiological assessments were performed on 156 patients (168 hip arthroplasties) who had a mean age of 67.7 (SD 9.7) years at operation. In the assessed group, 26 of 159 (16.4%) of femoral stems which had not already been revised and 19 of 159 (11.9%) of acetabular cups were definitely loose. In total, 52 of 168 (31%) of hips had either been revised or had definite evidence of loosening of a component. We could not establish any relationship between clinical and radiological outcomes. Despite the fact that the clinical outcome and rate of revision for the Elite Plus appeared to meet international standards, our findings give us cause for concern. We believe that joint registries should include radiological surveillance in order to provide reliable information about medium-term outcomes for hip prostheses.