Aim
Young athletes returning to sport after anterior cruciate ligament (ACL) injury have a 10-15% risk of contralateral ACL rupture. The addition on lateral extra-articular tenodesis (LET) to ACL reconstruction (ACLR) has been shown to reduce graft strain and failure rates, however, its effect on the native ACL remains unclear. The aim of this study was to evaluate the influence of LET on native ACL strain, anterior translation, rotational stability, and ACL torque in cadaveric knees and to compare outcomes between modified Lemaire and modified Ellison LET techniques.
Methods
Twenty fresh-frozen cadaveric knees were randomized to undergo either modified Lemaire or modified Ellison LET. Biomechanical testing was performed sequentially in the native ACL-intact state, following LET, following LET reversal, and following ACL transection. A 6-degrees-of-freedom joint motion simulator was used to evaluate knees under isolated anterior loading, isolated internal rotation loading, and combined loading conditions at 0°, 30°, 60°, and 90° of knee flexion. Primary outcome measures included anterior tibial translation, internal rotation displacement, ACL force, and ACL torque across all testing conditions. Data were analyzed using repeated-measures analysis of variance (ANOVA) for each biomechanical testing scenario.
Results
LET significantly reduced ACL force during isolated anterior loading and ACL torque during both rotational and combined loading conditions, with the greatest unloading effect observed at lower flexion angles. During isolated anterior loading, LET significantly reduced ACL force at 0° and 30° of flexion compared with the native knee condition. Under combined loading conditions, post-LET knees demonstrated reduced anterior translation compared with the native condition at 0° (p = 0.005) and 30° (p = 0.009). No statistically significant differences were identified between modified Lemaire and modified Ellison techniques, although modified Lemaire demonstrated a trend toward greater ACL unloading.
Conclusion
In cadaveric knees, LET provides an offloading effect on the native ACL while improving anterior and rotational stability, particularly at lower flexion angles. These findings provide a biomechanical rationale for a potential protective effect against ACL injury and support further investigation into the prophylactic role of LET to prevent ACL rupture in high-risk athletes.
