The Effect of Tibial Attachment Site on Graft Impingement in an Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament reconstructions were performed in 14 cadaveric knee specimens using a 6-mm wide polypropylene graft. The graft was passed through a femoral tunnel at the attachment site of the anterior medial bundle of the anterior cruciate ligament. Seven tibial positions were evaluated as to the change in attachment site distance with passive range of motion and impingement on the intercondylar notch as the knee was passively ranged from 0 degree to 90 degrees of flexion. Impingement was also evaluated while the knee was extended by pulling through the quadriceps tendon. The tibial placement site affects the change in attachment site distance with passive range of motion and impingement on the intercondylar notch. Grafts passed through drill holes anterior and lateral to the insertion of the anterior fibers of the anterior cruciate ligament consistently produced impingement on the anterior outlet of the intercondylar notch. Knee extension with quadriceps tendon pull produced graft impingement in a greater arc of flexion than passive extension. Based on this study, optimum placement of the tibial hole should be at the insertion of the anterior medial fibers of the anterior cruciate ligament. Impingement recognized during surgery can be alleviated with notchplasty. With passive extension there should be a 3-mm clearance between the anterior portion of the intercondylar notch and the ligament graft to prevent the graft from impinging when the knee is actively extended.