Changes to volumetric bone mineral density and bone strength after stroke : a prospective study

Abstract

Stroke survivors experience accelerated bone loss and increased fracture risk, particularly in paretic weight bearing limbs. Understanding how these changes unfold and their relationship to stroke severity and physical activity could help in the development of targeted interventions to prevent or reduce the severity of these outcomes. The primary aim of this study is to investigate the time course and magnitude of changes in volumetric bone mineral density within the first year after stroke, and to examine relationships with physical activity and motor recovery. Design: This is a prospective, observational study of 43 nondiabetic, nonambulant adults with first ever hemispheric stroke. Primary outcome: The primary outcome was the difference in six-month change of total volumetric bone mineral density between paretic and nonparetic distal tibiae, measured at 7% of bone length site using high-resolution peripheral quantitative computed tomography. Secondary outcomes: The secondary outcomes are cortical and trabecular volumetric bone mineral density, cortical thickness, and total and cross-sectional areas of distal tibiae and radii of paretic and nonparetic limbs. Also included are total body and regional bone mineral density derived using dual-energy X-ray absorptiometry, physical activity measured using accelerometry, and motor recovery (Chedoke McMaster Stroke Assessment). Discussion: Measuring the timing and magnitude of changes to volumetric bone mineral density and bone structure from immediately after stroke, and relationships between these changes with physical activity and motor recovery will provide the basis for targeted interventions to reduce fracture risk in stroke survivors.