USING HIGH-RESOLUTION PERIPHERAL QUANTITATIVE COMPUTED TOMOGRAPHY TO STUDY TIBIAL BONE CHANGES DURING CHRONIC STAGE OF STROKE RECOVERY

H. Ouyang¹, T. Miller¹, M. Pang¹

¹The Hong Kong Polytechnic University, Department of Rehabilitation Sciences, Kowloon, Hong Kong

Background: Secondary bone loss after stroke leads to a substantial increased risk of fragility fractures. High-resolution peripheral quantitative computed tomography (HR-pQCT) enables the measurement of macrostructure, microstructure and geometry of long bones, and provides an estimation of bone strength (failure load).

Purpose: To examine how bone density, macrostructure, and microstructure of the distal tibia changed in people with chronic stroke and to identify the factors associated with the change in failure load of the hemi-paretic distal tibia.

Methods: Forty-six individuals with chronic stroke (21 women, mean age=60 Years; mean post-stroke onset=6 years) participated in the study. The distal tibia measured bilaterally twice using high-resolution peripheral computed tomography (HR-pQCT), first the time of study registration and again 2 years later. Blood flow volume of popliteal artery was measured by Doppler Ultrasound. 10-meter walking test was used to assess walking speed. Multiple hierarchical regression analysis was used to identify predictors of the change in failure load of the hemi-paretic distal radius.

Results: In the paretic leg, there was significant decline in both cortical bone density (-1.18%), trabecular bone density (-1.28%), cortical thickness (-1.95%), cortical area (-1.83%) and trabecular thickness (-0.58%) after two years follow up. Among these, the change of cortical bone density, trabecular bone density and cortical thickness were significantly associated with reduction of the failure load during the 2-year follow-up period. After accounting for relevant factors, baseline blood flow volume (F change=5.99, p=0.019) and change in walking speed (F change: 5.48, p=0.024) improved the regression model for predicting the 2-year change in failure load of the hemi-paretic distal tibia.

Conclusions: Reduction in failure load of the hemi-paretic distal tibia during the 2-year follow-up period was mostly explained by decrease in cortical and trabecular bone density, and cortical thickness. Individuals with poorer baseline vascular health and less improvement in mobility tended to show more decline in tibial bone strength on the paretic side.

Implications: Vascular health and mobility function are two potential target areas for improving lower limb bone health in people with chronic stroke.

Funding acknowledgements: General Research Fund (granted by Research Grants Council (General Research Fund; 151031/18M), PhD studentship granted by Hong Kong Polytechnic University.

Keywords:
Stroke
Bone
Vascular

Topics:
Neurology: stroke

Did this work require ethics approval? Yes

Institution: The Hong Kong Polytechnic University

Committee: Institutional Review Board

Ethics number: HSEARS20161229002-02