Muscle weakness,spasticity and disuse contribute to demineralization and geometric changes in the radius following chronic stroke

Summary Bone health status of the radius in individuals with chronic stroke was evaluated using peripheral quantitative computed tomography. Bone mineral density and cortical thickness on the affected side were compromised when compared with the unaffected side. Muscle weakness, spasticity, and disuse were identified as contributing factors to such changes. Introduction Following a stroke, demineralization and geometric changes occur in bone as a result of disuse and residual impairments, and these can contribute to an increased risk of fragility fractures. Methods This study used peripheral quantitative computed tomography (pQCT) to evaluate volumetric bone mineral density and geometry at the midshaft radius in people living with chronic stroke. Older individuals with chronic stroke were recruited. Each subject underwent a pQCT scan of the midshaft radius at the 30% site on both upper limbs. Muscle strength, motor function, spasticity, and chronic disuse were also evaluated. Data from 47 subjects (19 women) were assessed. Results A significant difference was found between the two limbs for cortical bone mineral content, cortical bone mineral density, cortical thickness, and polar stress-strain index. There was no significant side-to-side difference in total bone area. Percent side-to-side difference in muscle strength, spasticity, and chronic disuse were significant determinants of percent side-to-side difference in cortical bone mineral content and cortical thickness. Conclusions The findings suggest that following chronic stroke, endosteal resorption of the midshaft radius occurred with a preservation of total bone area. Muscle weakness, spasticity, chronic disuse significantly contributed to demineralization and geometric changes in the radius following chronic stroke.