Test methods to detect hip and knee muscle weakness and gait disturbance in patients with hip osteoarthritis.

OBJECTIVE To evaluate test methods for hip and knee muscle weakness and gait disturbance. DESIGN Test-retest. SETTING Orthopedic university clinic. PARTICIPANTS Ten young (age, 36+/-6 y) and 13 elderly (age, 69+/-8 y) healthy volunteers and 11 patients (age, 69+/-8 y) with unilateral hip osteoarthritis (OA) were tested for muscular strength. Twenty-five volunteers (age, 42+/-14 y) underwent gait analysis. INTERVENTIONS A dynamometer assessing maximal voluntary isometric force of hip and knee muscles and an optosensor walkway detecting limp were developed. Tests evaluated reproducibility and tolerance in patients with OA and elderly subjects. MAIN OUTCOME MEASURES Relative coefficient of variation (CV%) and force (in newtons). RESULTS CV% for unilateral strength measurements ranged from 7% to 12% for specific muscle groups. CV% for gait parameters ranged from 4% to 8%, except for the double-support phase. Tests were well tolerated, and no patient had to discontinue because of fatigue. Differences related to sex, age, and disease were detected. CONCLUSIONS Our dynamometer system provides reliable measurements of hip and knee muscle strength in young and old people, and variation is comparable to previous data. Our photocell technique for gait analysis is reliable in people with normal gait. Both methods are attractive because they are affordable, nonstationary, and easy to use.