Function after total hip replacement for primary osteoarthritis.

We have reviewed 505 cases of surviving total hip replacement for primary osteoarthritis and studied the functional result and pain relief obtained between four and fourteen years after implantation. The risk factors were stratified and evaluated by multivariate statistical analysis. The patients were satisfied with the result of arthroplasty, and long-term function was improved in 95% of cases. The risk of postoperative hip pain was increased by knee pain, a snap-fit prosthesis with a 35 mm head, and a short wedge-shaped femoral stem, and by replacement at an early age. Function was impaired postoperatively by hip pain, bilateral hip disorders, intercurrent disease affecting locomotion and by old age at the time of surgery. The functional result was not related to the time from operation. The functional result after hip arthroplasty can be evaluated in a logical, unbiased and thorough way using multivariate statistical analysis.