Bone density and macrostructure of the radius in patients after chronic stroke : relationship to muscle function and cardiovascular health

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Bone density and macrostructure of the radius in patients after chronic stroke : relationship to muscle function and cardiovascular health

 

Author: Cheng, Qun Ada
Title: Bone density and macrostructure of the radius in patients after chronic stroke : relationship to muscle function and cardiovascular health
Degree: M.Phil.
Year: 2011
Subject: Cerebrovascular disease -- Patients -- Rehabilitation.
Bone densitometry.
Muscles.
Cardiovascular system.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Rehabilitation Sciences
Pages: 177 leaves : col. ill. ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2462489
URI: http://theses.lib.polyu.edu.hk/handle/200/6259
Abstract: Background and purpose: Secondary bone loss in the upper extremity is a common complication after stroke, which would increase the incidence of fractures, especially in the wrist region. However, the extent to which different stroke impairments are associated with bone health status in the paretic upper extremity is not well understood. The objectives of this study were to (1) assess the side-to-side difference in areal bone mineral density (aBMD) of the forearm using dual-energy X-ray absorptiometry (DXA), and densitometric and geometric parameters of the radius diaphysis and epiphysis using peripheral quantitative computed tomography (pQCT) among patients after chronic stroke, (2) compare the side-to-side difference in DXA- and pQCT-derived parameters between individuals with chronic stroke and age-matched healthy control subjects, and (3) identify the determinants of DXA-derived aBMD of the paretic forearm and pQCT-derived bone strength indices of the paretic radius. Methods: A total of 65 chronic stroke patients, and 34 healthy individuals participated in the study. DXA was used to evaluate the aBMD of the 1/3 region, mid-region, and ultradistal region of the forearm , and pQCT was used to evaluate volumetric BMD (vBMD), bone geometry, and bone strength indices at the radius distal epiphysis and diaphysis on both sides. Each subject was also evaluated for grip strength, spasticity, motor function, and disuse of the paretic upper extremity. Indicators of cardiovascular health including the oxygen consumption rate (VO₂) during the Six Minute Walk Test, stroke volume index (SI), cardiac output index (CI), large and small artery elasticity index (C₁ and C₂) were also measured. Results: The results showed that in the stroke group, the DXA-derived aBMD values in different regions of the forearm on the paretic side were significantly lower than those on the non-paretic side, and that the side-to-side differences in aBMD values in these patients were greater than those of their healthy counterparts. The pQCT results also revealed significantly lower vBMD and bone strength index values in the paretic radius epiphysis and diaphysis when compared with the non-paretic side among the patients after stroke, whereas the control group had no significant side-to-side difference in the same parameters. Multiple regression analysis showed that after accounting for age, gender, post-stroke duration and body mass index, grip strength was the most important determinant of the aBMD of the various regions of the paretic forearm, and the bone strength indices of the radius epiphysis and diaphysis in the stroke group. Conclusions: This study suggests that among the various stroke-related neuromuscular and cardiovascular impairments, muscle weakness is the most important determinant of the DXA-derived aBMD values and pQCT-derived bone strength indices. Promoting muscle strength of the paretic upper extremity may be an important treatment strategy to enhance or maintain bone mass in the paretic upper extremity, and warrants further investigations.

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