Effects of lateral/medial wedged insoles on the kinematics and kinetics during normal walking

Despite their wide clinical application and success, our understanding of the effects of insoles is relatively limited. The purpose of this study was to assess the biomechanical effects of wearing lateral/medial wedged insoles on subtalar and knee joints during normal walking. Motion analysis was conducted with a 3D motion-analysis system and a ground reaction force analysis using force plate when subjects walked with three different insole conditions: 5-degree medial wedge, no wedge, and 5-degree lateral wedge. Significant differences were found in subtalar or ankle joint motion in coronal and sagittal planes compared with the no-wedge condition. No differences were found in knee joint motion in the coronal and axial planes. The lateral-wedge insole reduced the knee varus moment and increased subtalar pronation moment in mid-stance during walking. At footstrike, however, the lateral wedge increased the knee varus moment and reduced the subtalar supination moment. The medial-wedge insole increased the knee varus moment and decreased subtalar pronation moment during the mid-stance phase. However, the medial wedge reduced the knee varus moment and increased subtalar supination moment at footstrike. The results of this study indicate that the influence of the insoles varied during the stance phase. Therefore, it is requested to select the shape of insole based on the injury mechanism, the location of the pain and the injury prevention.