SOCKET MIGRATION AFTER CHARNLEY ARTHROPLASTY IN RHEUMATOID-ARTHRITIS AND OSTEOARTHRITIS - A ROENTGEN STEREOPHOTOGRAMMETRIC STUDY

Socket migration and rotation in the Charnley total hip replacement we re evaluated by roentgen stereophotogrammetric analysis in 23 patients with rheumatoid arthritis and 23 patients with osteoarthritis. The tw o groups were matched with regard to age and sex. The follow-up time w as two years. In the rheumatoid patients socket migration was most pro minent in the proximal direction and averaged 0.6 mm at 24 months as c ompared with 0.1 mm in the osteoarthritic group (p = 0.0003). Within t he rheumatoid group a preoperative acetabular protrusion in five patie nts was associated with increased migration and rotation in all direct ions. The increased proximal migration in rheumatoid arthritis was con sistent (p = 0.0009) even after the exclusion of the five protrusion c ases. In the rheumatoid patients there was a correlation between low b ody-weight and proximal migration, but there was no such correlation i n the osteoarthritic group. Our results suggest that socket fixation i s less secure in patients with advanced inflammatory arthritis.