We implanted 71 metal-backed, porous-coated, hemispheric, press-fit Duraloc-100 cups in 68 consecutive patients. In 61 patients, the femoral stem was a cementless Spotorno and in ten a cemented Lubinus SP II. A 28-mm Biolox ceramic head was used with both stems. After an average follow-up of 4 (3.7-5.9) years, we examined 67 hips. Radiolucencies were described in three zones according to DeLee and Charnley, and migration was measured on serial radiographs using the computerassisted EBRA method. Total migration of more than 1 mm within the first 2 years occurred in 22/62 cups. Nine cups showed more than 1.5 mm total migration within the first 2 years and more than 2 mm within the whole period. The presence of post-operative radiolucencies correlated significantly with a total migration value of more than 2 mm within the first 2 years (p=0.02). Post-operative radiolucencies in zone 1 correlated with a total migration value of more than 2 mm within the first 2 years (p=0.027) and more than 2.5 mm within the whole period (p=0.051). These correlation values might reflect the quality of operative technique, particularly reaming, and implant selection.Résumé Nous avons implanté 71 cupules métal-back hémisphérique press-fit, revêtement poreux, Duraloc-100 chez 68 malades consécutifs. Pour 61 malades la tige fémorale était une Spotorno sans ciment et,pour dix, un tige cimenté Lubinus SP II. Un tête céramique Biolox 28 mm a été utilisée avec les deux tiges. Après une moyenne de suivi de 4 ans (3.7-5.9) nous avons examiné 67 hanches. Les liserés radiologiques ont été décrits dans les trois zones de DeLee et Charnley, et la migration a été mesurée sur des radiographies sérielles en utilisant la méthode EBRA assistée par ordinateur.

Background and purpose After total hip arthroplasty, dislocations are a frequent complication and are difficult to treat in some patients. A great variety of implants and antiluxation mechanisms are used in surgical therapy.Methods 8 patients had 9 Duraloc Constrained Inlays implanted at our clinic between October 2003 and November 2006, for recurrent dislocations. A retrospective follow-up study was carried out.Results All patients suffered a failure of the expanding ring, the metal ring being squeezed out of the polyethylene notch. The mechanism of failure can be explained by impingement due to the implant design. At the time of writing, 3 patients have had to undergo revision surgery.Interpretation The Duraloc Constrained Inlay has shown unacceptably high failure rates.