Purpose: The purpose of this study was to compare knee kinematics and graft forces in anterior cruciate ligament (ACL) reconstruction combined with one of two superficial medial collateral ligament (sMCL) reconstruction techniques (parallel or triangular vector sMCL reconstruction).
Methods: Twenty porcine knees were divided into two groups (n = 20), parallel or triangular vector sMCL reconstruction, with both groups having anatomic single-bundle ACL reconstruction. The knees were tested under (1) an 89-N anterior tibial load, (2) 4 Nm internal and external rotational tibial torques, and (3) a 7 Nm valgus torque.
Results: With ACL/sMCL co-injuries, single-bundle ACL reconstruction alone does not restore anterior, valgus, and internal stability. Triangular vector sMCL reconstruction better restored anterior stability, and parallel sMCL reconstruction better restored valgus stability.
Conclusion: This study showed that single-bundle ACL reconstruction alone was not able to restore anterior tibial translation, valgus rotation, and external rotation of the intact knee with combined ACL and sMCL injuries and sMCL reconstruction was also required. The combined ACL and parallel sMCL reconstruction better restored valgus and external rotation stability, while the combined ACL and triangular vector method better restored anterior tibial translation. With combined ACL and severe sMCL injury, both ligaments should be reconstructed. The two sMCL reconstruction techniques exhibited slightly different kinematics and graft force; however, there was not enough difference to recommend one over the other.
Keywords: ACL; In situ force; Kinematics; sMCL.