Anatomic, All-Arthroscopic Reconstruction of Posterolateral Corner of the Knee: A Cadaveric Biomechanical Study

Purpose: To assess the role of anatomic reconstruction of the posterolateral corner (PLC) of the knee arthroscopically in cadaveric knees with simulated isolated grade III posterolateral instability. Methods: A total of 12 nonpaired, fresh-frozen cadaveric knees were biomechanically subjected to a 10-Nm varus moment, 5-Nm external and internal rotation torques, and 134-N posterior tibial load at 0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees of knee flexion (0 degrees for varus loading only). Testing was performed with an intact and sectioned PLC and after anatomic reconstruction of the PLC by an arthroscopic technique. Kinematics of each knee under various loading conditions was determined with a robotic universal force/moment sensor testing system. Results: After sectioning, significant increases were found in varus rotation at 0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees of knee flexion; in external rotation at 15 degrees, 30 degrees, 60 degrees, and 90 degrees of knee flexion; in internal rotation at 60 degrees of knee flexion only; and in posterior translation at 15 degrees and 30 degrees of knee flexion. After reconstruction, full recovery of knee stability was observed in varus rotation, external rotation, internal rotation, and posterior translation at all selected flexion angles without any overconstraint of knee kinematics. Conclusions: Anatomic reconstruction of the PLC can be performed arthroscopically with isolated grade III posterolateral instability of the knee, and nearly normal stability of the knee can be restored.