Biomechanical comparison of single-bundle and anatomical double-bundle reconstructions for grade Ⅲ medial collateral ligament injury

Abstract

To evaluate and compare knee joint stability of grade Ⅲ medial collateral ligament (MCL) injury treated by single-bundle and anatomical double-bundle reconstruction methods, thus providing biomechanical basis for clinical treatment. Nine fresh cadaver specimens of normal human knee joints were randomly divided into 3 groups on average. In intact MCL group: The anterior cruciate ligament (ACL) was detached and reconstructed with single-bundle techniques, and the MCL was intact. In single-bundle and double-bundle reconstruction groups, the superficial MCL (sMCL), posterior oblique ligament (POL), and ACL were all detached to manufacturing grade Ⅲ MCL injury models. After single-bundle reconstruction of ACL, the sMCL single-bundle reconstruction and anatomical double-bundle reconstruction of sMCL and POL were performed, respectively. Biomechanical evaluation indexes included anterior tibial translation (ATT), internal rotation (IR), valgus rotation (VAL), and stresses of MCL and ACL under internal rotation and valgus torques at different ranges of motion of the knee joint. There was no significant difference in ATT at full extension and flexion of 15°, 30°, 45°, 60°, and 90° between groups ( P>0.05). At full extension and flexion of 15°, the IR and VAL were significantly higher in single-bundle reconstruction group than in double-bundle reconstruction group and intact MCL group ( P<0.05). At flexion of 30°, the VAL was significantly higher in single-bundle reconstruction group than in double-bundle reconstruction group and intact MCL group ( P<0.05). While there was no significant difference between double-bundle reconstruction group and intact MCL group ( P>0.05). There was no significant difference in the stresses of MCL and ACL between groups under the internal rotation and valgus torques at all positions ( P>0.05). MCL anatomical double-bundle reconstruction can acquire better valgus and rotational stability of the knee joint compared with single-bundle reconstruction.