Dual-energy x-ray absorptiometry analysis was used to determine the
periprosthetic bone-mineral content of ten femora that had been obtained at
the autopsies of five elderly patients who had had an AML (anatomic
medullary locking) prosthesis in situ for seventeen to eighty-four months.
Clinical radiographs showed resorptive remodeling changes characteristic of
femora containing this implant. Before the absorptiometry was performed, an
identical prosthesis had been inserted into the contralateral, normal femur
of each cadaver. The mean difference in the periprosthetic bone-mineral
content between the remodeled femora and the femora in which the prosthesis
had been implanted post mortem ranged from 7 to 52 per cent, with the
bone-mineral content always less in the remodeled femora. The greatest mean
decrease in bone-mineral content (45 per cent) occurred adjacent to the
proximal one-third of the remodeled femora. The percentage decrease in
periprosthetic bone-mineral content in the remodeled femora had an inverse
linear relationship with the corresponding bone-mineral content of the
contralateral control femora. Preoperative analysis of bone density may
therefore be useful for prediction of the extent of resorptive
bone-remodeling after total hip replacement.