Usefulness of Muscle Stiffness Evaluated by Ultrasonography for Detecting Muscle Change Related to Contracture in Frail Older Adults.

BACKGROUND

Ultrasonography can be used to evaluate the echo intensity (EI) and strain ratio (SR) to identify muscle quality and stiffness, respectively. EI and SR are affected by aging, frailty, and joint angle positions. We investigated the effects of aging and frailty on muscle EI and SR at different joint angle positions, and identified a useful measurement method to reflect muscle changes related to contractures in frail older adults.

METHODS

This study had a cross-sectional design. Twenty-two healthy young adults (young group), 22 non-frail older adults (non-frail group), and 22 frail older adults (frail group) participated in this study. The range of motion (ROM) of hip abduction, EI, and SR of the adductor longus in the zero- and full-abduction positions were measured. To investigate the effects of aging and frailty, the Kruskal-Wallis test, followed by the post-hoc Steel-Dwass test, was used. In addition, to confirm whether EI and SR in each position were useful for assessing contracture, Spearman's correlation test was used.

RESULTS

ROM and SR in full-abduction were significantly lower in the frail group than in the other groups and lower in the non-frail group than in the young group. The SR in full-abduction (ρ = 0.73, < .001) and in zero-abduction (ρ = 0.41, < .001) showed strong and moderate correlation with the ROM, respectively.

CONCLUSIONS

SR in full-abduction is affected by both frailty and aging and is useful for evaluating muscle stiffness related to contracture in frail older adults.