Efficacy of teriparatide in the treatment of nontraumatic osteonecrosis of the femoral head: a retrospective comparative study with alendronate

Background: Collapse of the femoral head associated with nontraumatic osteonecrosis (NOFH) is one of the most common causes of disability in young adult patients. Excessive bone resorption by osteoclast coincident with the suppression of osteogenesis are believed to be responsible for collapse progression. Alendronate that inhibits bone resorption by inducing osteoclast apoptosis has been traditionally used for treating NOFH; however, several reports documented serious complications by the use of this drug. On the other hand, teriparatide activates osteoblasts leading to an overall increase in bone volume, and is expected to reduce the progression of femoral head collapse in NOFH. Therefore, the present study was undertaken to examine pharmacological effects of teriparatide on collapse progression of NOFH and to compare these effects with alendronate. Methods: We conducted a retrospective study in our facility for comparing the pharmacological effects of teriparatide and alendronate on 32 NOFH patients diagnosed with osteoporosis. Between 2007 and 2013, patients were treated with daily administration of 20 mu g teriparatide (15 patients: 18 hips), or with 35 mg of alendronate once a week (17 patients: 22 hips). The mean period of follow-up was 18.7 months. The progression of collapse was evaluated prior to the administration and later every three months by anteroposterior radiographs. Collapse progression with > 1 mm was defined as advanced collapse, while with < 1 mm was defined as stable radiologic disease. Student's t-test and the chi-square test was used to do compare the pharmacological effects of the two groups. Results: Treatment with terparatide had a tendency to reduce the rate of advanced collapse as compared to that with alendronate (p = 0.105). Kaplan-Meier curves related to stable radiologic disease showed that teriparatide-treated patients had better stable states than these treated with alendronate (p = 0.08, log-rank test). Moreover, treatment with teriparatide resulted in a significant reduction in collapse progression as compared to that with alendronate, noted at the end of follow-up period (p = 0.049). Conclusion: The present study suggests that teriparatide has greater pharmacological effects than alendronate for treating NOFH and preventing the collapse of femoral head.