抄録
Cementless total hip arthroplasty is a useful reconstructive method for patients with hip diseases. However, the appearance of osteopenia of the proximal femur around the implant is a major problem, and several studies have documented objectively the phenomenon of stress shielding in the implanted bone. The purpose of this study was to measure the chronological change of bone mineral density of the femur with a cementless femoral prosthesis using microdensitometry.
Over a one-year period, 29 hips were assessed at regular intervals. The original diagnoses were osteoarthritis in 25 hips, avascular necrosis of the femoral head in 2 hips, and rapidly destructive coxarthropathy in 2 hips. The bone mineral density, the width of bone (D), width of marrow (d), and cortical index (CI: D-d/D) were calculated for the three conditions.
At the proximal part of the femur, d showed an increase at one year but there was no significant progress from that time. CI showed a decrease at one year and a gradual increase after that. At the distal end of the prosthesis, there was no change in bone mineral density 2 years after surgery, but 3 years later, d showed a decrease and CI showed a slight increase.
This study suggests that microdensitometry is an applicable method for evaluating the quantitative bone change of the femur around a prosthesis.
