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.