Migration and wear of long-term successful Charnley total hip replacementsT. Ilchmann, MD, Orthopaedic Surgeon1; L. Markovic, MD, Research Fellow2; A. Joshi, MCh, Orth, FRCS, Research Fellow2; K. Hardinge, MCh Orth, FRCS, Consultant Orthopaedic Surgeon2; J. Murphy, FRCS, Consultant Orthopaedic Surgeon2; and H. Wingstrand, MD, PhD, Associate Professor1
1 Department of Orthopaedics, Lund University Hospital, S-221 85 Lund, Sweden. Correspondence should be sent to Dr T. Ilchmann at BG Unfallklinik, Schnarrenbergstrasse 95, D-72076 Tübingen, Germany. We analysed in-vivo migration and wear over a long period of all-polyethylene acetabular cups which had not been affected by mechanical loosening. The selection criteria of regular radiological follow-up, good clinical outcome (Charnley score of 5 or 6), continued walking without crutches and no radiological signs of loosening of the acetabular cups were fulfilled by 25 Charnley total hip arthroplasties. Mean migration, measured by the Nunn method, was 0.6 mm in the medial and 0.2 mm in the cranial direction. The mean yearly rate of wear was 0.05 mm and 0.04 mm, with six and two cups having no detectable wear, as measured by the Livermore and Charnley-Cupic methods, respectively. The maximal detected wear was 3.7 mm. There were no changes in the rate of wear with time. Computerised Ein Bild Röntgen Analyse (single-image radiological analysis) measurements of 20 hips indicated plastic deformation of the cups. We conclude that long-term successful cups do not migrate and have a very low rate of wear which was not affected by ageing of the polyethylene. There was no evidence that polyethylene wear alone caused mechanical loosening of the cup but high rates of wear seem to have an adverse prognostic value in terms of the long-term survival of the prosthesis. This article has been cited by other articles:
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