Anteromedial and posterolateral graft kinematics of a double-bundle ACL reconstruction: a 3D computer simulation

Background: The posterolateral graft has been reported to fail more frequently than the anteromedial graft in double-bundle ACL reconstructions. This study investigated the graft kinematics using a 3D modelling technique.

Methods: Twenty subjects performed a stair-ascending activity under dual fluoroscopy surveillance. A double-bundle ACL reconstruction was simulated on those healthy knees using an anteromedial portal technique. The graft-tunnel interaction was described using the graft-tunnel angle and the range of the graft-tunnel edge contact (GTEC).

Results: The femoral graft-tunnel angle of the anteromedial/posterolateral graft was 97.6 ± 7.5/100.7 ± 7.7° and the tibial graft-tunnel angle was 158.8 ± 6.5/146.5 ± 8.9° at knee extension. The femoral GTEC ranges were 23.2 ± 5.3-28.1 ± 7.6° for both grafts and the tibial GTEC ranges were 27.3 ± 2.2-34.5 ± 2.1° during stair-ascending.

Conclusion: The femoral graft-tunnel angle was larger than on the tibial side and the GTEC angles influenced the PL graft more, implying that grafts may experience a less optimal biomechanical environment at the femoral tunnels.