Hip structure analysis of bisphosphonate-treated Japanese postmenopausal women with osteoporosis

The purpose of this study was to clarify the effects of a 1-year treatment with either alendronate or risedronate on the proximal femoral geometry among Japanese women with osteoporosis by hip structure analysis. Postmenopausal women who had taken at least 90% of their prescription for alendronate (35 mg/week, 94 patients) or risedronate (17.5 mg/week, 181 patients) for 1 year were retrospectively analyzed. In the alendronate treatment group, bone mineral density (BMD), cross-sectional area (CSA), section modulus and average cortex significantly increased by 0.81, 1.35, 2.23 and 0.97% at the narrow neck and increased by 2.19, 2.28, 2.85 and 1.11% at the intertrochanteric, respectively. Buckling ratio at the intertrochanteric significantly decreased by 2.50%. The CSA, section modulus and average cortex at the shaft significantly increased at 1 year. In the risedronate treatment group, the CSA, section modulus and average cortex at the narrow neck significantly increased by 0.80, 0.95 and 0.89%, respectively. BMD, CSA, section modulus, and average cortex at the intertrochanteric significantly increased by 1.61, 0.88, 2.05 and 0.79%, respectively, and buckling ratio significantly decreased by 1.53%. BMD, CSA, section modulus, and average cortex at the shaft significantly increased. The percent change of section modulus was significantly correlated with that of BMD, CSA and average cortex and negatively correlated with that of buckling ratio at all regions in both treatment groups. Statistically significant differences between the alendronate and risedronate groups were seen for section modulus in the narrow neck and CSA in the intertrochanteric. In conclusion, Japanese osteoporotic women treated by either alendronate or risedronate showed significant improvements of geometry in proximal femur within 1 year.