Abstract
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.
