The biomechanical effect of tunnel placement on ACL graft forces in double‐bundle ACL reconstruction – A 3D computational simulation

BACKGROUND: The posterolateral (PL) graft experiences a high failure rate in anterior cruciate ligament double-bundle (DB) reconstruction. It is hypothesized that tunnel positions could dramatically affect the graft forces. METHODS: A validated computational model was used to simulate DB reconstruction with various femoral PL tunnel locations (8-11 mm center-center tunnel spacing). Graft fixation was simulated at both 0° and 30°. Knee biomechanics were examined with the knee under a 134 N anterior load and 400 N quadriceps load at 0°, 30°, 60°, and 90° of flexion. Graft forces, tibial translation, and tibial rotation were calculated. RESULTS: PL graft forces at full extension increased with increasing tunnel spacing under both fixation settings, but the knee kinematics was not dramatically affected. CONCLUSION: Small changes in the femoral PL tunnel position could result in large changes in graft forces, implying that precise PL tunnel position is an important factor in a successful DB reconstruction.