The Effect of Femoral Tunnel Position on Graft Forces During Inlay Posterior Cruciate Ligament Reconstruction

Abstract

Background: The femoral tunnel may be positioned centrally or eccentrically within the posterior cruciate ligament footprint during a single-bundle posterior cruciate ligament reconstruction.

Hypothesis: After reconstruction, graft forces are significantly different from those of the native posterior cruciate ligament and are affected by the position of the femoral tunnel.

Study Design: Controlled laboratory study.

Methods: The resultant force in the native posterior cruciate ligament was measured in nine cadaveric knees as the knee was flexed from —5° to 120° of flexion. Posterior cruciate ligament reconstruction was performed with the femoral side of the graft positioned centrally and then offset 5 mm eccentric to the central position.

Results: Mean graft forces were not significantly different between eccentric and central tunnel positions during passive knee extension between 120° and 0° of flexion; at 5° of hyperextension, the eccentric position generated significantly lower graft forces. For both reconstruction techniques, mean graft forces were significantly higher than those for the native posterior cruciate ligament beyond approximately 90° of flexion, for 5 N·m internal and external tibial torque; 5 N·m varus and valgus moment.

Conclusions: Graft force reductions achieved with the eccentric femoral position appear to be relatively small compared with the forces expected during rehabilitation and activities of daily living.

Clinical Relevance: After posterior cruciate ligament graft reconstruction, rehabilitation activities that load the knee at high degrees of flexion should be avoided to limit excessive forces on the maturing graft.