The Addition of Posterolateral Tenodesis in Isolated PCL Injuries and in Combination With Fanelli Type A Lesion of the Posterolateral Corner Decreases Rotatory Instability: A Biomechanical Study in Human Cadaveric Knees

Background: Posterior cruciate ligament (PCL) injuries may lead to significant anteroposterior and rotational knee instability. Traditional reconstruction techniques, including single-bundle (SB) and double-bundle (DB) approaches, have limitations in terms of restoring full biomechanical function. A posterolateral tenodesis (PLT) augmentation associated with PCL reconstruction has been described, consisting of a nonanatomic bundle that shares the PCL tibial tunnel, courses along the posterior aspect of the lateral femoral condyle from an intra-articular to an extra-articular position, and is fixed at the lateral femoral epicondyle to provide additional control of tibial external rotation. Purpose: To determine the impact of adding a posterolateral tenodesis (PLT) to a PCL reconstruction to restore knee rotational and posterior stability. Study Design: Controlled laboratory study. Methods: In total, 24 embalmed cadaveric human knees were randomized into 3 main groups: intact (control), isolated PCL-deficient, and combined PCL + posterolateral corner (PLC)–deficient (Fanelli type A). Each group underwent sequential reconstructions using SB and DB PCL techniques, with and without the addition of PLT. Biomechanical testing included measurements of posterior tibial translation (PTT) and external tibial rotation (ER) at 30° and 90° of flexion using a custom-built robotic testing machine and inertial sensors. Porcine flexor tendons were used as grafts. Results: Sectioning the PCL significantly increased both PTT and ER, with values peaking in the combined PCL + PLC-deficient group (PTT: 10.3 ± 0.8 mm; ER: –30.4°± 0.8° at 90° of flexion). SB and DB reconstructions alone partially restored stability, but residual laxity persisted, especially in the rotational parameters. The addition of PLT significantly reduced both PTT and ER. In the DB + PLT group with combined PCL + PLC injury, the PTT and ER values (3.2 ± 0.3 mm and –12.5°± 0.3°, respectively) were statistically indistinguishable from the intact group ( P > .05). Conclusion: Combined PCL and PLC injuries result in marked rotational and posterior instability. When added to SB or DB PCL reconstruction, PLT significantly improves biomechanical function, particularly regarding rotational control. These findings support the inclusion of PLT in surgical protocols addressing complex PCL-related instability. Clinical Relevance: Adding a posterolateral tenodesis to PCL reconstruction may reduce residual instability and improve outcomes in complex ligament injuries.