Longitudinal change in periprosthetic, peripheral, and axial bone mineral density after total hip arthroplasty

Abstract To determine the bone mineral changes after total hip arthroplasty, bone mineral densities (BMD) at the periprosthetic interface, lumbar spine, radius, and calcaneus were measured in a prospective and longitudinal observation. Twenty-four patients (24 joints) who had received a total hip arthroplasty and were followed longitudinally were enrolled in this study. The subjects comprised 2 men and 22 women with a mean age of 69.2 years at the time of surgery. Bone mineral measurements were performed at 1, 3, 6, 12, 18, 24, 30, and 36 months after surgery. The periprosthetic BMD after total hip arthroplasty continued to decrease for 6-12 months after surgery, and then recovered, except in Gruen zone 7 (the calcar region). The calcaneal BMD decreased rapidly for 3 months after surgery before increasing. The lumbar BMD showed a decreasing trend for 12 months after surgery, and then increased gradually. The radial BMD was not affected by surgery. We conclude that changes in the periprosthetic BMD after total hip arthroplasty show an apparent difference between zones, and also differ between the weight-bearing bones and the nonweight-bearing bones.