Endosteal bone loss after total hip arthroplasty.

Femoral endosteal bone loss has been shown to be part of the natural aging process and may be a factor in femoral component loosening following total hip arthroplasty (THA). In this study, changes in the femoral medullary canal width in 30 patients with aseptic femoral loosening following primary THA were compared with 30 matched control patients. The rate of canal expansion on the operated side was twice that of the nonoperated side and four times that of the control. After the onset of symptoms in the failure group, the rate of femoral expansion of the operated side doubled. Iliac crest biopsies showed a decrease in male patients for osteoid surface and appositional and bone formation rates when compared with literature controls. These results suggest that femoral medullary canal expansion may be a factor in femoral component loosening following THA. The increased rate of canal expansion after the onset of symptoms demonstrates the need for early surgical intervention to avoid excessive bone loss.