Influence of chronic stroke impairments on bone strength index of the tibial distal epiphysis and diaphysis

Abstract

The influence of various stroke impairments on bone health is poorly understood. This study showed that muscle function and small artery compliance were more strongly associated with the bone strength index at the tibial diaphyseal and epiphyseal regions, respectively. These impairments should be targeted in promoting bone health post-stroke. This study examined the bone structural properties of the tibial distal epiphysis and diaphysis after chronic stroke and identified the clinical correlates of the bone strength index measured at these sites. The tibial distal epiphysis (4 % site) and diaphysis (66 % site) were scanned on both sides in 66 chronic stroke patients and 23 control participants using peripheral quantitative computed tomography. Dynamic knee muscle strength, balance function, spasticity, arterial compliance, and endurance were also measured in the stroke group. At the 4 % site, multivariate analysis showed a significant side x group interaction effect (Wilk's lambda = 3.977, p < 0.001), with significant side-to-side differences in total volumetric bone mineral density (vBMD), trabecular vBMD, and bone strength index in the stroke group, but not in the control group. A significant side x group interaction was also found at the 66 % site (Wilk's lambda = 4.464, p < 0.001), with significant side-to-side differences in cortical vBMD, cortical area, cortical thickness, and bone strength index in the stroke group only. Balance and endurance were independently associated with bone strength index at both tibial sites in the paretic leg (p < 0.05) after adjusting for relevant factors in multivariate regression analysis. Small artery compliance and muscle strength were significantly associated with the bone strength index at the 4 % site and 66 % site, respectively. The influence of various stroke impairments on bone was region-specific. While muscle function was more strongly associated with the bone strength index in the diaphyseal region, the effect of vascular health was more apparent in the tibial epiphysis in the paretic leg.