Wear rate and medium-term survival of a cemented, moderately cross-linked polyethylene acetabular prosthesis.

INTRODUCTION: The moderately cross-linked Depuy Marathon® cemented acetabular component was introduced into the UK in 2007. The wear rate for the previously introduced Marathon® uncemented acetabular component has been reported to range from 0.06 to 0.01 mm/year. The aim of this study was to present the medium-term results and wear rate of the Marathon® cemented prosthesis used in primary total hip arthroplasty. METHODS: 103 Marathon® cemented acetabular components were implanted between 2008 and 2009 in primary arthroplasty, who were eligible for this study. All patients received a metal 28-mm head. Mean age was 68 years (range 27-87). Mean clinical follow-up was 55 months (range 50-61). Mean radiological follow-up was 46 months (range 24-57). Wear was calculated on AP radiographs using computer-assisted uni-radiographic technique. RESULTS: The mean wear was 0.37 mm (range 0.0-0.78 mm). The wear rate was calculated as 0.03 mm/year (95% confidence interval 0.02-0.06). Postoperative complications included deep vein thrombosis (2%) and dislocation (0.8%); there were no deep infections. There were no revisions for failure of the Marathon® cemented acetabular component. CONCLUSIONS: The Marathon® cemented acetabular component demonstrates satisfactory wear rates and survivorship at medium-term follow-up.

Clinical experience of revision of metal on metal hip arthroplasty for aseptic lymphocyte dominated vasculitis associated lesions (ALVAL).

There has been growing concern regarding the systemic and local effects of metal ions released from metal-on-metal hip resurfacings and total hip replacements, including the development of aseptic lymphocyte dominated vasculitis associated lesions (ALVAL). We describe our experience of treating 13 patients with failed metal on metal bearing hip prostheses secondary to this condition. Hip revision occurred at mean of 45 months following primary surgery. Groin pain was present in all patients. Other common features included large bursal swelling and mechanical symptoms. 3 patients developed their symptoms immediately postoperatively. The mean time to presentation was 21 months. Radiographic abnormalities noted included 3 patients with cup loosening and 2 patients with neck thinning. The mean cup inclination was 52 degrees. Surgical findings included bursal swellings and creamy brown fluid. Osteolysis was rarely seen. 12 revisions were achieved with primary implants and all patients had immediate symptomatic improvement. One patient was left with a pseudoarthrosis due to extensive soft tissue destruction. Diagnosis of ALVAL was confirmed histologically. The diagnosis of ALVAL should be considered in patients with unexplained pain from a metal on metal bearing hip arthroplasty. Surgical findings are typical and symptoms tend to resolve reliably following conversion to an alternative bearing surface.

Medium-term results with the Press Fit Condylar (PFC) Sigma knee prosthesis the Wrightington experience.

The PFC Sigma total knee was introduced in 1997, incorporating a number of design changes. We report the mid-term results of a consecutive series of PFC Sigma knee arthroplasties performed between November 1997 and December 1998. Out of a total of 156 patients (166 knees), 5 patients (5 knees) were lost to follow-up and 6 patients (6 knees) died of unrelated causes. This left 145 patients (155 knees), 90 female and 55 male, with a mean age of 70 years (range, 53-88) and an average follow-up of 90 months (range, 84-96). Posterior cruciate retaining components were used in 136 knees (88%) and posterior-stabilized in 19 (12%). The patella was resurfaced in 74 (48%) knees. Follow-up was at 3, 6 and 12 months, then yearly. Preoperative American Knee Society and Oxford scores were compared with follow-up scores. The Knee Society radiological score was used for radiographic assessment. One knee (0.6%) was revised due to aseptic loosening. One knee (0.6%) had superficial wound infection, which settled with oral antibiotics. Two knees became deeply infected. Of these, one resolved following early debridement, the other developed chronic infection. Using revision for any reason as the end-point our cumulative success rate was 99.4%. The mean preoperative Knee score improved from 45 (30-65) to 84 (45-92), Functional score from 38 (25-55) to 73 (50-95) and Oxford score from 43 (33-52) to 17 (14-29). Radiographic review showed radiolucent lines in 54 (35%) tibial and 17 (11%) femoral components. The Radiological Knee Society score was less than 4 in all except one tibia where the score was 7. Our study shows excellent clinical results with the PFC Sigma total knee replacement after almost eight years follow-up.