A research team conducted a cross-sectional study to test whether residual and/or intact limb isometric hip strength was associated with lower-limb prosthesis users’ walking speed, endurance, and balance. The results suggested that unilateral transtibial and transfemoral prosthesis users’ walking and balance performance may depend on different hip muscles and different facets of hip strength. Amputation level-specific hip strength interventions may therefore be required to improve walking and balance performance.
The researchers used multiple linear regression to evaluate the relationship between isometric measures of residual and intact limb hip strength and walking and balance performance among14 transtibial and 14 transfemoral prosthesis users.
Measures of isometric hip muscle strength, including peak torque, average torque, torque impulse, and torque steadiness (i.e. consistency with which an isometric torque can be sustained) were derived from maximum voluntary hip flexion, extension, abduction, and adduction torque signals collected with a motor-driven dynamometer. Walking speed, endurance, and balance were assessed by administering the 10-Meter Walk Test, Two-Minute Walk Test, Four Square Step Test, and Narrowing Beam Walking Test, respectively.
The researchers found that residual limb hip extensor max torque and abductor torque steadiness explained 51-69 percent of the variance in transtibial prosthesis users’ walking speed, endurance, and balance. In contrast, intact limb hip abductor torque impulse explained 33-48 percent of the variance in transfemoral prosthesis users’ walking speed, endurance, and balance.
A strategy emphasizing intact limb hip, ankle, and potentially knee muscle contributions to walking and balance adopted by transfemoral prosthesis users may be due to a variety of prosthesis and biomechanical factors that limit the efficiency with which transfemoral prosthesis users can exploit the strength of their residual limb hip muscles while walking.
The open-access study, “The relationship of hip strength to walking and balance performance in unilateral lower limb prosthesis users differs by amputation level,” was published in PM&R.
