A longitudinal HR-pQCT study of alendronate treatment in postmenopausal women with low bone density: Relations among density, cortical and trabecular microarchitecture, biomechanics, and bone turnover.

Abstract

The goal of this study was to characterize longitudinal changes in bone microarchitecture and function in women treated with an established antifracture therapeutic. In this double-blind, placebo-controlled pilot study, 53 early postmenopausal women with low bone density (age = 56 ± 4 years; femoral neck T-score = -1.5 ± 0.6) were monitored by high-resolution peripheral quantitative computed tomography (HR-pQCT) for 24 months following randomization to alendronate (ALN) or placebo (PBO) treatment groups. Subjects underwent annual HR-pQCT imaging of the distal radius and tibia, dual-energy X-ray absorptiometry (DXA), and determination of biochemical markers of bone turnover (BSAP and uNTx). In addition to bone density and microarchitecture assessment, regional analysis, cortical porosity quantification, and micro-finite-element analysis were performed. After 24 months of treatment, at the distal tibia but not the radius, HR-pQCT measures showed significant improvements over baseline in the ALN group, particularly densitometric measures in the cortical and trabecular compartments and endocortical geometry (cortical thickness and area, medullary area) (p < .05). Cortical volumetric bone mineral density (vBMD) in the tibia alone showed a significant difference between treatment groups after 24 months (p < .05); however, regionally, significant differences in Tb.vBMD, Tb.N, and Ct.Th were found for the lateral quadrant of the radius (p < .05). Spearman correlation analysis revealed that the biomechanical response to ALN in the radius and tibia was specifically associated with changes in trabecular microarchitecture (|ρ| = 0.51 to 0.80, p < .05), whereas PBO progression of bone loss was associated with a broad range of changes in density, geometry, and microarchitecture (|ρ| = 0.56 to 0.89, p < .05). Baseline cortical geometry and porosity measures best predicted ALN-induced change in biomechanics at both sites (ρ > 0.48, p < .05). These findings suggest a more pronounced response to ALN in the tibia than in the radius, driven by trabecular and endocortical changes.

• Authors: Andrew J Burghardt, Galateia J Kazakia, Miki Sode, Anne E de Papp, Thomas M Link, Sharmila Majumdar
• Journal: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research (J Bone Miner Res) Vol. 25 Issue 12 Pg. 2558-71 (Dec 2010) ISSN: 1523-4681 [Electronic] United States
• PMID: 20564242 (Publication Type: Journal Article, Randomized Controlled Trial, Research Support, N.I.H., Extramural)
• Copyright: Copyright © 2010 American Society for Bone and Mineral Research.

Chemical References

• Bone Density Conservation Agents
• Alendronate

Topics

• Absorptiometry, Photon
• Alendronate (administration & dosage, pharmacology, therapeutic use)
• Biomechanical Phenomena
• Bone Density (drug effects)
• Bone Density Conservation Agents (administration & dosage, pharmacology)
• Bone Remodeling (drug effects)
• Bone and Bones (diagnostic imaging, drug effects, physiology)
• Female
• Humans
• Longitudinal Studies
• Middle Aged
• Postmenopause (drug effects)
• Radius (diagnostic imaging, drug effects, physiology)
• Statistics, Nonparametric
• Tibia (diagnostic imaging, drug effects, physiology)
• Time Factors
• Tomography, X-Ray Computed
• Treatment Outcome