THE INFLUENCE OF CLINICAL FACTORS ON PERIPROSTHETIC BONE REMODELING

The femurs of 11 patients with well-functioning unilateral hip replace ments were retrieved at autopsy and analyzed for periprosthetic bone r emodeling by dual energy xray absorptiometry. Each case involved a fem ur with a porous-coated endoprosthesis; the endoprosthesis remained im planted for an average of 5.9 years. In the contralateral femur, a mat ching prosthesis was implanted in vitro, to serve as a control for com parisons. There was an average 22.6% decrease in bone mineral content in the in vivo implanted femur (range, 5.4%-47.4%). Females experience d an average bone loss of 31.2%, which was significantly higher than t he 12.3% average loss in males. Longitudinal analysis revealed an aver age decrease in bone mineral content of 42.1% proximally, 23% in the m idsection, and 5.5% distally. Percent decreases in total bone mineral content were correlated with the following clinical variables: weight, age, implant diameter, duration of implantation, and contralateral fe moral bone mineral content. Only the bone mineral content of the contr alateral femur had a strong predictive value. Bone loss was greater in femurs with low bone mineral content than in those with high bone min eral content. Weight, age, implant diameter, and duration of implantat ion were not correlated with bone loss.