Longitudinal bone loss in the paretic leg and its contributing factors in individuals with chronic stroke: A 2-year prospective cohort study

Summary: Post-stroke fracture risk necessitates investigation of bone properties and contributing factors. The decline in paretic tibia failure load post-stroke was attributed to decreased trabecular bone density and thickness at 2-year follow-up. Less decline in bone strength was associated with better leg blood flow, walking speed, strength, and activity at baseline. Purpose: To delineate long-term changes in distal tibia bone properties after stroke and identify their associated factors. Methods: High-resolution peripheral quantitative computed tomography (HR-pQCT) scans of the bilateral distal tibia were performed in 46 chronic stroke participants (age, 60.4 ± 7.8 years; post-stroke onset, 6.3 ± 4.2 years) and 45 controls (age, 57.7 ± 6.3 years) at baseline and 2 years later. We measured the change in the estimated failure load (indicator of bone strength), volumetric bone mineral density (vBMD), geometry, and microstructure. Blood flow volume of the popliteal artery, muscle strength, sensory function, and gait speed were also assessed. Results: In the paretic leg of stroke participants, a significant decline in estimated failure load was observed (− 3.39%, p < 0.01), which was greater than that of the non-paretic side (− 1.93%, p < 0.01) and controls (− 1.89 to − 2.18%, p < 0.05). The deterioration in estimated failure load was accompanied by a decline in trabecular vBMD and thickness. Greater arterial blood flow, higher walking velocity, better muscle strength, and higher physical activity level at baseline at 2-year follow-up portended less decline in estimated failure load. Conclusions: During the 2-year follow-up, there was a decline in estimated failure load of the paretic distal tibia among people with chronic stroke, attributed to a decreased trabecular density and thickness. Greater decline in estimated tibial bone strength was associated with lower arterial blood flow volume and motor function on the paretic side.