Knee Biomechanics during Walking in Individuals with Anterior Cruciate Ligament Repair: The Role of a Custom 3D Printed Knee Brace

BackgroundAnterior cruciate ligament (ACL) injuries frequently lead to altered gait biomechanics and muscle activation patterns, increasing the risk of osteoarthritis. Knee braces are commonly used to address these issues although a lack of consensus remains regarding their clinical benefits. The recent emergence of 3D-printed braces, lighter and personalized, could improve rehabilitation. ObjectivesTo evaluate the effect of a novel custom-made 3D-printed knee brace (Provoke) in individuals after unilateral ACL reconstruction during walking. The brace incorporates an asymmetrical hinge system aimed at stabilizing the knee joint while minimizing compensatory movements. MethodsFourteen participants with unilateral ACL reconstruction wore the Provoke brace while walking at comfortable and fast paces. Knee kinematics and kinetics, and muscular activity (rectus femoris, vastus medialis, and semitendinosus) were assessed with and without the brace. Two-tailed non-parametric paired T-tests were used to assess the biomechanical effect of the brace. Results and conclusionsThe Provoke brace improved knee kinematics, facilitating a more neutral knee position by reducing valgus angles (-1.95{degrees}), and increasing flexion angles (+1.14{degrees}). Additionally, it enhanced muscle activation, particularly of the rectus femoris, suggesting improved quadriceps function. Overall, the Provoke brace effectively improves knee function and reduces muscle imbalances in individuals undergoing ACL reconstruction. It may help prevent further injury and reduce the risk of post-traumatic osteoarthritis development. The long-term effects of brace use in ACL rehabilitation must be investigated. Key PointsO_LIWalking while wearing Provoke brace allow to reduce knee valgus angles which could counteract the development of post-traumatic osteoarthritis. C_LIO_LIBraced walking may mitigate the stiffened knee gait strategy by increasing the peak knee flexion angle during the stance phase of the gait. C_LIO_LIIncreased rectus femoris activation during early stance phase could improve knee function and stability, acting against quadriceps weakness often observed after anterior cruciate ligament reconstruction. C_LI