Knee kinematics of the lateral extra-articular tenodesis using an anterior shifted insertion point in order to avoid femoral tunnel interference

Abstract-Text (inkl. Referenzen und Bildunterschriften)

Purpose:   Potential tunnel interference between anterior cruciate ligament reconstruction (ACLR) and modified Lemaire lateral extra-articular tenodesis (LET) in combined ACLR+LET knee joint treatment can be avoided when placing the LET insertion point anterior to the lateral epicondyle. The aim of the study was to investigate tibiofemoral knee kinematics of this alternative, anterior LET insertion point and compare them to the originally described insertion point.

Methods:  Six fresh-frozen human knee joints were tested on a test bench in the following states: 1) native, 2) anterolateral insufficient, 3) original Lemaire (oLET; insertion point: 4 mm posterior and 8 mm proximal to the epicondyle), 4) anterior Lemaire (aLET; insertion point: 5 mm anterior and 5 mm proximal to the epicondyle). Internal tibial rotation and anterior translation were statically investigated under an internal tibial torque in 0°, 30°, 60° and 90° of flexion and during a simulated Lachman test respectively. Additionally, the range of internal tibial rotation and anterior translation were dynamically investigated by a simulated pivot-shift test. Tibiofemoral kinematics were measured using an optical 3D motion analysis system.

Results:  The aLET showed an internal tibial rotation comparable to the native state for all tested flexion angles except 90° (0°: P = 0.154; 30°: P = 0.154; 60°: P = 0.176; 90°: P < 0.001). The oLET showed an internal tibial rotation below the values of the native state for all tested flexion angles (0°: P < 0.001; 30°: P = 0.002; 60°: P = 0.009; 90°: P < 0.001). No differences in anterior translation and internal tibial rotation were found between the oLET and aLET during simulated Lachman and pivot-shift test, approximating the native state.

Conclusions:  The aLET restored internal tibial rotation after anterolateral insufficiency to the native state while decreasing the risk of an unphysiologically reduced internal tibial rotation compared to the oLET.