Effects of antiresorptive therapy on bone microarchitecture

Abstract

Dual-energy X-ray absorptiometry (DXA) is widely used to measure bone mineral density (BMD) for both clinical and research use. While DXA is well validated as a predictor of fracture, density is only one determinant of bone quality. Other potential major contributors to fracture risk reduction include bone morphology, bone microarchitecture, and the intrinsic physical properties of bone tissue. This chapter focuses on the effect of antiresorptive therapy on bone microarchitecture as assessed by (1) traditional two-dimensional histomorphometry of iliac crest bone biopsies and three-dimensional ex vivo micro-CT of biopsies and (2) imaging methods including high-resolution peripheral quantitative CT (HR-pQCT) that assess bone microarchitecture in vivo. Studies show that trabecular microarchitecture is generally preserved or improved with antiresorptive treatment as assessed by histomorphometry and micro-CT of iliac crest biopsies. However, trabecular microarchitectural changes as assessed by HR-pQCT are generally not detected, possibly due to limited imaging resolution and modest reproducibility for trabecular microarchitecture measurements. Cortical microarchitecture is generally preserved or improved as assessed by both iliac crest bone biopsy histomorphometry with micro-CT and by HR-pQCT of the distal radius and distal tibia. These studies highlight the important positive effects of antiresorptive treatment on trabecular and cortical microarchitecture at axial and peripheral sites.