Graft Length Changes and Optimal Knee Flexion Angles for Fixation in Posterolateral Corner Reconstruction: An In Vivo 3-Dimensional Simulation Analysis

Abstract

Background: Changes in graft length according to knee flexion and the ideal knee flexion angle at the time of graft fixation for posterolateral corner (PLC) reconstruction have yet to be clearly defined.

Purposes: To investigate graft length changes according to knee flexion and determine the optimal graft fixation angle for knee flexion in PLC reconstruction.

Study design: Descriptive laboratory study.

Methods: Ten healthy male volunteers underwent computed tomography at varying knee flexion angles (0°, 30°, 45°, 60°, and 90°). The Larson, LaPrade, Arciero, and Kim techniques were performed on 3-dimensional knee models reconstructed from the computed tomography scans. The lengths of each theoretically reconstructed graft were recorded and compared according to knee flexion angle changes.

Results: In the Larson technique, the lengths of both arms of the sling were the longest at 30° of knee flexion but were not significantly different between 45° and 60° of knee flexion. In the LaPrade, Arciero, and Kim techniques, the length of the lateral collateral ligament arm at 30° of knee flexion was significantly longer than that at other knee flexion angles (P < .05), except at 0° of knee flexion. The length of the popliteus tendon arm in the LaPrade and Kim techniques, and the length of the popliteofibular ligament arm in the Arciero technique, increased with knee flexion and became the longest at 60° of knee flexion (P < .05).

Conclusion: In the LaPrade, Arciero, and Kim techniques, the lengths of the lateral collateral ligament and popliteus complex component arms were greatest at 30° and 60° of knee flexion, respectively. In the Larson technique, the lengths of the anterior and posterior arms were greatest at 30° of knee flexion. The authors recommend securing each arm of the graft at the point of its greatest length.

Clinical relevance: This study presents in vivo data regarding graft length changes according to knee flexion and offers an optimal graft fixation angle for PLC reconstructions through various techniques.