Mechanical and sensorimotor implications with ankle osteoarthritis.

OBJECTIVE To understand the mechanical and sensorimotor adaptations that may occur with ankle osteoarthritis (OA). DESIGN Case-control. SETTING Biodynamics research laboratory. PARTICIPANTS Subjects with ankle OA (n=8; 4 males, 4 females) were matched to healthy controls (n=8; 4 males, 4 females). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Mechanical joint stability was assessed with an instrumented ankle arthrometer. Static balance was measured using a force platform during a double-legged stance. Isometric ankle/foot complex strength in the sagittal and frontal plane was assessed with a handheld dynamometer. Last, subjective level of function was assessed using the foot and ankle disability index. RESULTS There were significant group x side interactions for anterior displacement, inversion rotation, eversion rotation, ankle isometric strength, and the foot and ankle disability index (P<.05). The affected ankle of the OA group demonstrated significantly more mechanical stiffness, more impairments in ankle/foot isometric strength, and less subjective level of function than the matched controls. Additionally, the ankle OA group exhibited significantly more center of pressure displacement, total velocity, and medial-lateral velocity (P<.05). CONCLUSIONS These limitations observed in joint laxity, postural control, muscle strength, and perceived function provide evidence that patients with ankle OA display a number of characteristics that affect joint stability and overall function. These identified impairments necessitate the need for rehabilitation and exercise programs to be developed to help improve joint stability and function in patients with ankle OA.