Acetabular cup migration after primary total hip arthroplasty in rheumatoid arthritis and its influencing factors: A comparative study with osteoarthritic hip

Abstract

Patients with rheumatoid arthritis of hip has potential risk factors for mechanical complications in primary total hip arthroplasty (THA) due to osteopenic periacetabular bone stock, increased bone turnover, and resorptive bone activity in the acetabular region. Several authors have reported a higher rate of acetabular cup loosening in rheumatoid arthritis than in osteoarthritis. However, long-term follow-up research on migration of acetabular components in patients with rheumatoid arthritis is lacking. The authors compared retrospectively the radiographic migration profiles between the patients with rheumatoid arthritis and those with osteoarthritis. A total of 268 patients (mean age, 53.8 years; 62 men, 206 women; 293 hips) underwent primary THA for rheumatoid arthritis or osteoarthritis between Jan 2001 and Jan 2013. 122 patients (139 hips) with rheumatoid arthritis (RA; RA group) were compared with 146 patients (154 hips) with osteoarthritis (OA; OA group). The two groups were matched for age, sex, body mass index, bone mineral density, the history of smoking and diabetes, disease duration, and implant design. The mean follow-up period was 134 months in the RA group and 122 months in the OA group. Radiological evaluation was performed using Einzel-Bild-Röntgen-Analyse (EBRA) software regarding the acetabular cup loosening and migration of acetabular component. Early cup migration was defined as total cup migration of >1mm within two years. Patient-related factors and laboratoy tests were assessed to identify influencing factors for cup migration. In RA group, early cup migration was observed in 13 hips (9.4%). Acetabluar cup loosening occurred in three cups (2.2%) and two acetabular components were revised. In OA group, early cup migration was observed in 5 hips (3.2%). Acetabular cup loosening occurred in one cup (0.6%), which required a revision surgery. There was significant difference in the incidence of early cup migration between two groups, but not in acetabular cup loosening (p=0.03, p=0.266, respectively). Mean total migration was higher in RA group (2.62 mm) than in OA group (1.44 mm, p=0.005). In patients younger than 50 years, the total cup migration was significantly higher than those in patients older than 50 years (p=0.005). Among the laboratory tests, anti-cyclic citrullinated peptide (anti-CCP) antibody and rheumatoid factor (RF) were associated with acetabular cup migration in RA group. The patients with positive anti-CCP antibody or those with positive RF showed significantly higher total migration of acetabular component than those with negative anti-CCP antibody or RF (p=0.001, p=0.022, respectively). Between seropositive and seronegative RA patients, there were significant difference in total migration and migration at 4 years with higher values in seropositive RA patients (p=0.005, p=0.019, respectively) Acetabular cup stability in primary THAs of RA patients in intermediate-term follow-up was less stable in terms of cup migration compared to OA patients. Acetabular cup migration was higher especially in patients with seropositive RA less than 50 years of age. For these patients, secure stable fixation of the acetabular component at index operation and regular serial surveillance of cup migration are required.