Effect of foot wedge positions on lower-limb joints, pelvis and trunk angle variability during single-limb stance

BackgroundWedge posted foot orthotics could prevent abnormal compensatory motions in the proximal joints by aligning the subtalar joint and ankle. However, the effect of wedge positions on the compensations of the subtalar joint and its proximal joints and segments in maintaining posture are not well understood.ObjectiveTo test the effect of four wedge positions on compensatory actions of the subtalar joint, ankle, knee, hip, pelvis and trunk by determining their angle variability during single-limb standing posture.MethodFourteen healthy males were tested in single-limb stance during 64 s. A wooden wedge with an inclination of 4.6° was placed under the anterior, posterior, lateral and medial sides of the dominant foot. A no wedge barefoot condition was also tested. Angle variability was measured by determining the root mean square (RMS) deviation value for each joint angle.ResultsThe frontal plane angle variability for the subtalar joint was about 6-times greater for the medial and posterior wedge compared to the no wedge condition. For the anterior and posterior wedges, angle variability of the ankle and hip in the sagittal plane and pelvis and trunk in the transverse plane was about 2–3-times higher by comparison to the no wedge condition.ConclusionWedge positions may affect differently the angular variability of the subtalar joint and its proximal joints and segments in their respective planes of movement. Similar patterns of changes in angle variability were found in the joints and segments which have the same plane of movement during single-limb standing posture.