ACL Graft with Extra-Cortical Fixation Rotates Around the Fe
A Study was conducted to measure the percentage of the tunnel filled by the graft and determine the amount and location of the graft–tunnel contact with knee motion and under external knee loads.An understanding of the behavior of a new ACL graft in the femoral tunnel during knee motion and external loading can provide information pertinent to graft healing, tunnel enlargement, and graft failure.

Single bundle anatomical ACL reconstruction was performed on six cadaveric knees. The percentage of tunnel filled and the contact region between graft and tunnel at the femoral tunnel aperture were calculated.

--The graft occupies approximately 70% of the femoral tunnel aperture and anterior tibial loading tended to reduce this value.

--The graft contacted about 60% of the tunnel circumference and the location of the graft–tunnel contact changed significantly with knee flexion.

Conclusively, this study demonstrated that during the knee bending and the contract during the loading of the knee, the graft tends to spin around the circle of the tunnel. The 'windshield-wiping' and 'bungee cord' effects can lead to femoral tunnel enlargement, graft healing and injury. After surgery the graft can move considerably into the tunnel. The graft-tunnel healing needs to be permitted throughout sufficient time of recovery. The interference vector fixation or a graft with bone blocks, which can allow a faster return to activity, should be considered in order to decrease graft motion.