Background: Despite improved biomechanical stability and kinematics with anatomic anterior cruciate ligament (ACL) reconstruction, concerns regarding notch impingement of the graft have persisted, particularly with increasingly anterior tibial tunnel position. The potentially mitigating effect of anatomic femoral socket position, however, has not been evaluated.
Hypothesis: Placement of the femoral socket in the central or posterolateral bundle footprint reduces the risk and magnitude of graft impingement after ACL reconstruction compared with placement in the anteromedial bundle footprint.
Study Design: Controlled laboratory study.
Methods: This study employed computer-assisted navigation in a cadaveric model to evaluate the effect of tibial and femoral tunnel position on ACL graft impingement. Sixteen cadaveric knees were tested using the Praxim ACL Surgetics Navigation System, with the tibial tunnel positioned in the footprint of the anteromedial bundle and the femoral socket placed in the (1) anteromedial bundle footprint, (2) center of footprint, or (3) posterolateral bundle footprint. The amount of maximum impingement, angle of initial impingement, and location of graft impingement were documented through a full arc of knee motion.
Results: Impingement occurred with all 3 femoral socket positions, but the mean angle of impingement with the anteromedial femoral position (42.8° ± 26.4°) was significantly greater (P < .003) than the mean angles of impingement with the central femoral position (19.4° ± 19.2°) and the posterolateral bundle femoral position (16.7° ± 13.3°).
Conclusion: Although notch impingement was seen in all femoral socket locations with an anteromedial tibial socket position, femoral socket position in a central or posterolateral bundle location may reduce the risk and magnitude of graft impingement after ACL reconstruction. Additional studies are necessary to determine the influence of these different constructs on graft isometry and knee kinematics.
Clinical Relevance: Anatomic femoral socket position in the center of the native ACL footprint may reduce the risk and magnitude of notch impingement compared with an anteromedial bundle position with ACL reconstruction.