An analysis of an anatomical posterolateral knee reconstruction: an in vitro biomechanical study and development of a surgical technique.

BACKGROUND To date, no surgical technique to treat posterolateral knee instability anatomically reconstructs the 3 major static stabilizing structures of the posterolateral knee: the fibular collateral ligament, the popliteus tendon, and the popliteofibular ligament. HYPOTHESIS Static varus and external rotatory stability would be restored to the reconstructed knee with a posterolateral knee injury. METHODS The anatomical locations of the original fibular collateral ligament, popliteus tendon, and popliteofibular ligament were reconstructed using a 2-graft technique. Ten cadaveric specimens were tested in 3 states: intact knee, knee with the 3 structures cut to simulate a grade III injury, and the reconstructed knee. RESULTS For the varus loading tests, joint stability was significantly improved by the posterolateral reconstruction compared to the cut state at 0 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion. There were no significant differences between the intact and reconstructed knees at 0 degrees, 60 degrees, and 90 degrees for varus translation. For the external rotation torque tests, external rotation was significantly higher for the cut state than for the intact or reconstructed posterolateral knee. There was no significant difference in external rotation between the intact and reconstructed posterolateral knees at any flexion angle. CONCLUSIONS This 2-graft technique to reconstruct the primary static stabilizers of the posterolateral knee restored static stability, as measured by joint translation in response to varus loading and external rotation torque, to knees with grade III posterolateral injuries.