Mapping Bone Changes at the Proximal Femoral Cortex of Postmenopausal Women in Response to Alendronate and Teriparatide Alone, Combined or Sequentially

Abstract

Combining antiresorptive and anabolic drugs for osteoporosis may be a useful strategy to prevent hip fractures. Previous studies comparing the effects of alendronate (ALN) and teriparatide (TPTD) alone, combined or sequentially using quantitative computed tomography (QCT) in postmenopausal women have not distinguished cortical bone mineral density (CBMD) from cortical thickness (CTh) effects, nor assessed the distribution and extent of more localized changes. In this study a validated bone mapping technique was used to examine the cortical and endocortical trabecular changes in the proximal femur resulting from an 18-month course of ALN or TPTD. Using QCT data from a different clinical trial, the global and localized changes seen following a switch to TPTD after an 18-month ALN treatment or adding TPTD to the ALN treatment were compared. Ct.Th increased (4.8%, p<0.01) and CBMD decreased (-4.5%, p<0.01) in the TPTD group compared to no significant change in the ALN group. A large Ct.Th increase could be seen for the switch group (2.8%, p<0.01) compared to a significantly smaller increase for the add group (1.5%, p<0.01). CBMD decreased significantly for the switch group (-3.9%, p<0.01) and was significantly different from no significant change in the add group. Ct.Th increases were shown to be significantly greater for the switch group compared to the add group at the load bearing regions. This study provides new insights into the effects of ALN and TPTD combination therapies on the cortex of the proximal femur and supports the hypothesis of an increased bone remodeling by TPTD being mitigated by ALN.