The effect of medial wedge inserts on knee adduction moments during a cutting movement

PURPOSE: To assess whether using medial wedge inserts in footwear (MWF) could reduce biomechanical variables associated with noncontact anterior cruciate ligament (ACL) injuries focusing primarily on knee adduction moments (KAM). METHODS: Nine female university students completed four sidestep cuts in three different footwear conditions (neutral, 3.5 degree medial wedge, and 5 degree medial wedge). Wedge conditions were created using ultra-high density EVA material Podowedge inserts (A. Algeo Ltd., Liverpool, England), creating a wedge on the medial aspect of the shoe from the heel to the 1st metatarsal-phalangeal joint. Ground reaction forces and 3D lower limb kinematics were recorded. RESULTS: Peak external KAM during the stance phase was lower in the 5 degree wedge condition (74.66 ± 28.35 N·m) compared to the neutral condition (83.10 ± 26.66 N·m). However, despite a small to medium effect size (ES = 0.32), this difference was nonsignificant (p = 0.065). There was no effect for the 3.5 degree wedge (ES = 0.00). CONCLUSIONS: Using a large degree medial wedge inserts was able to elicit a small effect in reducing KAM suggesting MWF could potentially reduce the risk of an ACL injury but future research is warranted.