Background: Osteonecrosis of the femoral head is the most common
diagnosis leading to total hip arthroplasty in young adults. Joint-preserving
treatment options have been mainly surgical, with inconsistent results.
Alendronate (a bisphosphonate agent) has been shown to lower the prevalence of
vertebral compression fractures and could potentially retard the collapse of
an osteonecrotic femoral head. The purpose of this study was to test the
effect of alendronate in preventing early collapse of the femoral head in
patients with nontraumatic osteonecrosis.
Methods: Forty patients with Steinberg stage-II or III nontraumatic
osteonecrosis of the femoral head and a necrotic area of >30% (class C)
were randomly divided into alendronate and control groups of twenty patients
each. Patients in the alendronate group took 70 mg of alendronate orally per
week for twenty-five weeks, while the patients in the control group did not
receive this medication or a placebo. The patients were observed for a minimum
of twenty-four months. Harris hip scores, plain radiographs, and magnetic
resonance imaging scans were obtained.
Results: During the study period, only two of twenty-nine femoral
heads in the alendronate group collapsed, whereas nineteen of twenty-five
femoral heads in the control group collapsed (p < 0.001). One hip in the
alendronate group underwent total hip arthroplasty, whereas sixteen hips in
the control group underwent total hip arthroplasty (p < 0.001).
Conclusions: Alendronate appeared to prevent early collapse of the
femoral head in the hips with Steinberg stage-II or IIIC nontraumatic
osteonecrosis. A longer duration of follow-up is needed to confirm whether
alendronate prevents or only retards collapse.
Level of Evidence: Therapeutic Level I. See Instructions
to Authors for a complete description of levels of evidence.