Meta-Analysis: How Do Bone Properties Change After Stroke?

Significant changes in bone mass may occur after stroke and are more pronounced in the paretic limbs and during the first few months after the acute event, according to study results published in Osteoporosis International.

Previous studies have reported a significant reduction in bone mineral density (BMD) after stroke, in addition to unfavorable changes in bone geometric properties on the hemiparetic side. Furthermore, as muscle contractions provide an important source of mechanical loading to bone and bone adaptations, the impact of stroke on skeletal muscle may impair bone tissue.

The goal of the current systematic review was to collect and assess data from existing literature regarding the effects of stroke on bone properties. In addition, the researchers explored the relationship between muscle function and bone properties after stroke.

The researchers searched several databases from inception to January 2019, including Cochrane, Ovid (Medline, Embase), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus, and Pubmed, and included studies that reported bone properties in people who had a stroke. Quality of reporting in the included articles was assessed using a standardized Study Quality Assessment Tool from the National Heart, Lung, and Blood Institute under the National Institutes of Health.

Of 607 records found, 59 articles were included in the systematic review (4 interventional studies and 55 observational studies). Overall, 39 of the studies were cross-sectional, with measurements taken from the paretic and nonparetic sides at one time point. In 16 observational studies, measures were taken from the same individuals at several time points relative to stroke onset.

In 11 studies exploring bone properties in individuals with acute stroke, assessment of side-to-side differences in bone properties revealed that there were no differences in areal BMD or volumetric BMD between the paretic and nonparetic sides.

In studies of subacute and chronic stroke, skeletal sites in the paretic limbs had a more pronounced decrease in bone quality than the nonparetic limbs. In addition, the researchers noted more compromised bone properties in the paretic upper limb vs the paretic lower limb. Rate of change in bone properties slowed as duration after stroke increased, but there was not a uniform time point at which bone changes reached a steady state. “These results highlight the importance of therapeutic interventions mitigating the rapid decline in bone integrity within the first year following stroke,” noted the investigators.

They also concluded that there was a strong relationship between bone quality and muscle strength in both the upper and lower limbs. Muscle spasticity had a negative effect on bone integrity in the paretic upper limb, but the effect of spasticity on the paretic lower limb was not clear.

The studies included in the review had several limitations, including that there were only a small number of longitudinal studies, missing data on the effects of stroke on microstructural properties of bone, and relatively few studies focused on the acute and subacute phases of stroke.

“The results of this review have important clinical implications, particularly for factors related to early intervention, muscle strength training, and long-term management strategies to enhance bone health post-stroke,” wrote the researchers.

“This review has also revealed the knowledge gaps in the field which should be addressed in future research,” they added, highlighting a need for long-term longitudinal studies of bone health after stroke and more research into the effect of functional capacity after stroke on bone properties.

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Reference

Yang FZ, Jehu DAM, Ouyang H, Lam FMH, Pang MYC. The impact of stroke on bone properties and muscle-bone relationship: a systematic review and meta-analysis [published online November 13, 2019]. Osteoporos Int. doi:10.1007/s00198-019-05175-4