The effect of gait modification on the response of medial meniscus extrusion during gait in patients with knee osteoarthritis

Background: An increase in medial meniscus extrusion during weight-bearing conditions is associated with the progression of medial knee osteoarthritis (OA). Toe-out gait modification has been known to reduce the knee adduction moment (KAM); however, its effect on reducing the increase in medial meniscus extrusion in patients with knee OA remains unclear.Research question: To (1) evaluate the effect of toe-out gait on the increase in medial meniscus extrusion and the KAM in patients with medial knee OA and (2) investigate the synergetic effect of lateral wedge insoles in combination with toe-out gait in determining the most effective intervention for reducing medial meniscus extrusion during gait.Methods: Twenty-five patients with medial knee OA were enrolled in this study.Participants walked under four conditions: normal gait, toe-out gait, normal gait with lateral wedge insoles, and toe-out gait with lateral wedge insoles. Medial meniscus extrusion and KAM peaks during gait were measured using ultrasound and a threedimensional motion analysis system in each condition. These parameters were compared among the four conditions using repeated measures analysis of variance. Results: The increase in medial meniscus extrusion and the second KAM peak were significantly lower in all interventions compared with those observed during normal gait. However, there was no significant difference among the interventions.Significance: This study suggested that toe-out gait reduces the increase in medial meniscus extrusion and is associated with the reduction of the second KAM peak. However, no synergistic effect of lateral wedge insoles and toe-out gait was observed.