15-21-year results of the Charnley low-friction arthroplasty.

Ninety-three patients had had 116 Charnley low-friction arthroplasties (LFA) 15 to 21 years (mean, 16.6 years) previously. Their mean age at surgery was 53 years (range, 20-71 years). Fifty-two had osteoarthritis and 19 had rheumatoid arthritis. At follow-up, 85.3% were completely pain-free and 11.2% had occasional discomfort. Seventy-eight percent had near full or full range of movements. Acetabular bone-cement junction was unchanged in 32, and 20 had nonprogressive demarcation of the outer one third measuring less than 1 mm in width. In 36, socket demarcation was complete. Medial femoral cortex was unchanged in 56% and 44% showed loss of definition. Endosteal cavitation of the femur was present in 20.7%. Subsidence of the stem or the stem-cement complex was present in 29%. The diameter of the femoral cortex near the tip of the stem remained unaltered in 83.6%. The rate of socket wear was 0.096 mm/year, and there was a highly significant correlation between time and wear but no correlation between wear and patient's weight. Twenty-two and five-tenths percent of sockets migrated; this was statistically related to the depth of socket wear. The excellent clinical results of a relatively unsophisticated early surgical technique strongly supported the correct concept of the low-frictional torque. Improvements in the surgical technique and component design will further improve the long-term results.