D1: Orthopaedic Biomechanics I

MEASURING THE RESTRAINING PROPERTIES OF THE FIBER BUNDLES WITHIN THE ACL AND PCL USING DOF RELEASE FIXTURE

Ryo Takeda, Keisuke Okuzumi, Keisuke Okuzumi, Katsuhiko Sasaki

Hokkaido University, Japan

The main focus of this study was to investigate the load capabilities of the anteromedial (AM) and posterolateral (PL) bundles of the ACL and the posteromedial (PM) and anterolateral (AL) bundles of the PCL A novel knee joint biomechanical testing platform was specially designed and developed for this study The platform consisted of a 6 axis force/torque sensor attached to a single axis material testing machine and a bespoke DoF passive fixture The fixture was designed to fix the femur and tibia bone of the knee joint specimen through bone cement and restaining bolts The passive fixture was capable of releasing or constraining two translational DoFs (medial-lateral (ML) and proximaldistal (PD)) and three rotational DoFs (internal-external (IE), varus-valgus (VV) and flexion-extension (FE) rotation) by means of bearings and locking screws The fixtures also contained two IMUs for measuring the rotational and translational motion of the femur and tibia attachments respectively 16 porcine stifle joints were used as knee joint specimens The specimens were subject to three different ligament states for each cruciate ligament : ACL and PCL intact (Intact), AM bundle cut (AM cut), AM+PL cut (ACL cut), PM bundle cut (PM cut) and PM+AL cut (PCL cut) at 90 deg of flexion In addition, the DoFs on the passive fixture was released sequentially Loads induced during anteriorposterior (AP) translation motion by the material testing machine were measured by the force/torque sensor and the secondary coupled motions by the IMUs As a result, the average AP directional load contributions for the ACL bundles were: 62% AM vs 37% PL The same results for the bundles within the PCL were: 5% PM vs 95% AL The developed platform was capable of quantifying the different functions of the fiber bundles within the cruciate ligament and relevant for evaluating methods of ligament reconstruction.
 

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