No difference in migration or wear between cemented low-profile cups and standard cups: A randomized radiostereographic study of 53 patients over 3 years

Abstract

Background: Minor design changes may cause major changes in implant performance. Thus, as part of a stepwise introduction of a new low-profile cup, we performed a randomized trial comparing it to a well-docu-mented standard cup. Patients and methods: 60 patients, stratified according to sex, weight, and age, underwent cemented total hip arthroplasty using a Lubinus SP2 stem with ceramic head and were randomized to either the new low-profile Lubinus Flanged Anti-Luxation cup (FAL) or the Lubinus Standard Eccentric cup (Standard). 7 patients were excluded and 53 (28 FAL) were evaluated at 3, 6, 12, and 36 months postoperatively. Primary outcome variables, cup migration (MTPM), and wear (total 3-dimensional femoral head penetration) were measured with radiostereometry (RSA). Clinical outcome was evaluated with the western Ontario and McMaster osteoarthritis index (Womac) and the visual analog pain score (VAS). Results: We found no difference in migration between the FAL and Standard cups. There was no difference in wear between the two cups and there was no correlation between wear and migration. 3 cups (2 FAL and 1 Standard) showed continuous migration of a magnitude that indicated an increased risk of early loosening. Clinical outcome was excellent, without any difference between the 2 groups. Copyright© Taylor & Francis 2007.