Anatomic Posterolateral Knee Reconstructions Require a Popliteofibular Ligament Reconstruction Through a Tibial Tunnel

Abstract

Background: No biomechanical study has been performed analyzing the merits of reconstructing the popliteofibular ligament (PFL) through a tibial tunnel with an anatomic reconstruction of the posterolateral knee. Hypothesis: There is no difference in an anatomic posterolateral knee reconstruction with or without a PFL reconstruction placed through a tibial tunnel in restoring knee motion to the intact, uninjured state, and the knee is not overconstrained with this reconstruction. Study Design: Controlled laboratory study. Methods: Eight paired knees were tested in the intact state and then sectioned to simulate a grade III posterolateral knee injury. The reconstruction for the first paired knee reconstructed the PFL (through a tibial tunnel), popliteus tendon, and fibular collateral ligament (group 1); the matched knee reconstruction involved only the popliteus tendon and fibular collateral ligament (group 2). Results: Reconstructions for group 1 knees restored knee motion to the intact state for all tested conditions at all knee flexion angles with no overconstraint of the knee. Without reconstructing the PFL (group 2), small but significant increases in motion were found for varus translation at 0° (3.0°), 20° (3.1°), and 60° (3.8°) of knee flexion compared with the intact state. At 60° and 90° of flexion, the reconstruction for group 2 had small but significant increases in internal rotation compared with the intact state (1.3° and 1.8°, respectively). Conclusion: Inclusion of the PFL through a tibial tunnel as part of an anatomic posterolateral knee reconstruction restores knee stability back to the intact state and does not overconstrain the knee. Furthermore, inclusion of the PFL through a tibial tunnel restored normal internal rotation. Clinical Relevance: The PFL should be included in anatomic reconstructions of grade III posterolateral knee injuries with placement through a tibial tunnel to best restore the intact, preinjury knee motion state and, most notably, normal internal rotation without evidence of overconstraint of the knee.