gms | German Medical Science

Objectives: The purpose of this biomechanical study was to compare the single femoral tunnel, modified Larson technique (LAR) and double femoral tunnel, Arciero technique (ARC) in terms of varus and external rotatory laxity for posterolateral corner (PLC) reconstruction. Additionally, three different angles for popliteus strand fixation of the ARC technique were investigated. It was hypothesized that ARC technique provides more stability in external rotation than the LAR (H1), with the highest rotational stability for fixation of the popliteus graft at 90° (H2).

Methods: Eight fresh-frozen human knees were tested in a knee test bench, designed to allow 6 degrees of freedom kinematics. Specimens were tested in four different states: native (NAT), posterlateral insufficiency (INS), LAR and ARC. LAR was fixed at 60° of flexion. For ARC, the graft was fixed at the fibular side and the popliteus strand was fixed as originally described at 30° and additionally at 60° and 90° of flexion (ARC30, ARC60, ARC90). The order of testing for the reconstruction techniques (LAR/ARC) was randomized. Specimens were subjected to external and varus rotation of 5 Nm, while tibial external rotation (ER) and varus rotation (VR) was measured in 0,° 30°, 60°, 90° of flexion. Wilcoxon signed rank tests were used to assess statistical relevance between paired groups at different states.

Results and conclusion: Both PLC reconstruction techniques have significantly improved VR and ER stability in all flexion angles compared with INS state (p=<0.05). At 60° and at 90° of flexion, ARC30 showed a significantly higher ER stability compared to LAR (ARC30 vs LAR at 60°: 21.2°±5.1 vs 15.4°±5.6 p=<0.05) (ARC30 vs LAR at 90°: 23.7°±5.6 vs 16.8°±6.3 p=<0.05). No significant differences between both reconstruction techniques were found under VR load. ARC30 showed no significant differences compared with NAT state in VR and ER at all flexion angles. Compared with NAT, LAR showed higher ER at 60° and higher ER and VR at 90° of flexion (p=< 0.05). No significant differences in ER and VR were found between ARC30, ARC60 and ARC90 at any flexion angle (p=>0.05).

With the ARC reconstruction technique the knee stability was restored much closer to the native uninjured state than with the LAR technique. ARC provided higher tibial ER stability compared to LAR at higher flexion angles (H1 accepted). Different femoral flexion angles for fixation of popliteus tendon strand during ARC did not show significant differences on knee stability (H2 rejected).