Survivorship of uncemented PE/metal acetabular components in young patients. Prospective study with an 8-13 year follow-up

Abstract

Introduction Although young patients with total hip prostheses are known to have a greater functional demand, there are few prospective studies on uncemented cups with a metal/polyethylene (PE) bearing surface. Purpose To assess the outcome and the survivorship of acetabular components in young patients with a minimum 8-year follow-up, as well as the factors leading to cup mechanical failure. Materials and methods Prospective study of 42 primary uncemented total hip arthroplasties with a metal/PE bearing surface, in 34 patients with a mean age of 52.5 years (range: 28-60), and initial diagnosis of primary osteoarthritis in 61% of cases. The Harris score was used for the functional assessment. Digitalized radiographs and computer image analysis were used to study the positioning and the incorporation of the components, as well as PE wear rates. Results Mean postoperative follow-up was 11 years (range: 8-13). Functionally, 36 cases (85.7%) had a satisfactory outcome. Radiologically there was one case of stem instability and 4 cases of acetabular instability, which had to be revised; there was also one case of a deep infection. Thirty-one cases (73.8%) showed some degree of PE wear, with a mean annual linear loss of 0.20 ± 0.09 mm. Aggregate PE survivorship at 11 years was 25% (95% CI: 37.1-64.5). The wear was more intense in the younger patients (p=0.05), in the more obese ones (p = 0.04) and in verticalized cups (p=0.01); no statistically significant relationship was found (p>0.05) with gender, previous diagnosis, neck length or use of acetabular screws. The cases with the greatest wear showed a higher incidence of periacetabular osteolysis (p=0.001). Conclusions Although the percentage of satisfactory results has been acceptable, the high incidence of survivorship-shortening PE wear would seem to preclude the use o fan uncemented metal/PE acetabular component in patients younger than 60 years of age, especially if they are obese.