Effects of the WISH-type S-form Hip Brace on Muscle Strength in Patients with Osteoarthritis of the Hip: A Short-term Longitudinal Study

Background: The WISH-type S-form hip brace (WISH brace) has been shown to significantly improve hip function, functional mobility, and gait biomechanics in patients with hip osteoarthritis. The aim of the current study was to evaluate the effects of the WISH brace over time on the strength of muscles around the hip and knee joints. Methods: A prospective short-term longitudinal study with a 6-month follow-up was conducted. Muscle strengths were measured using a handheld dynamometer. Results: The muscle strengths of hip flexion, hip abduction, and knee extension were lower in the affected limb than in the unaffected limb, whereas hip adduction muscle strength was reduced to the same extent in both the affected and unaffected limbs. This short-term longitudinal study revealed that only hip adduction and knee extension exhibited significant interaction between legs and time when measurement was performed without the WISH brace. Furthermore, the inherent hip abduction muscle strength of the affected limb was improved by the WISH brace so that the strength became the same as the unaffected limb. Conclusions: Improvement in abduction muscle strength of the affected limb by daily walking exercise with the WISH brace, which occurred with little interaction with the unaffected limb, may improve hip function.