The wear and prevalence of periprosthetic osteolysis at 5 to 8 years of follow-up of the Trilogy cup, which has a modular liner assembled during surgery, was compared with the Implex cup, which has a fixed liner preassembled at the factory. Sixty-three patients (65 hips) with a Trilogy cup and 64 patients (65 hips) with an Implex cup were match-paired for sex, age, height, weight, and diagnosis (osteoarthritis). All patients had a cemented stem with a 28-mm head and a successful clinical and radiographic result. After an average follow-up of 5.65 years, radiographs were studied to determine the total penetration, using the Livermore technique, and the presence of osteolysis. The average total wear in the Trilogy group was 0.47 mm (range, 0-1.95 mm); for the Implex cup, it was 0.43 mm (range, 0-1.45 mm) (P.99). One patient in each group presented with periacetabular osteolysis (P.99). There was no difference in the wear rate and prevalence of periprosthetic osteolysis between the 2 groups.