Abstract
Sixty-five hip joints in 48 cases with rheumatoid arthritis (RA) were surveyed for 6 months to 15 years (average 51.8 months) after total hip arthroplasty (THA) with Charnley type prosthesis. In subsequent clinical evaluations, results showed stable recovery with a remarkable improvement in pain. The incidence of clear zone (CZ) in the socket side was 50.8%, where CZ was often observed in Zone I and II. The incidence of CZ was higher at a socket setting angle of 40° or less than at one of 41° or more. CZ incidence was also higher in cases of protrusio acetabuli. There were no significant differences in CZ incidence in terms of the cement mantle, and with or without bone graft. The incidence of CZ in the stem side was 12.7%, high in Zone I, and also higher on the medial side than on the lateral side. There was a high incidence of CZ in the stem placed at a varus position, and in cases with an insufficient bone-cement mantle.
