Description of ACL Reconstruction
An ACL surgery requires precise knowledge of the anatomy of the knee, attachment sites of the ACL and knowledge on the other ligaments and structures of the knee. If one fails to replace an anterior cruciate ligament at its correct attachment sites or if other concurrent injuries are not treated, there is a much higher risk of failure of the ACL graft.
While there are two bundles of the ACL, the anteromedial and posterolateral bundles, there is still controversy as to whether both should be reconstructed as a single ligament or as two separate ligament grafts. While the double-bundle ACL reconstruction technique appeared very promising initially, many research groups, including ours, have significantly narrowed the indications for double-bundle ACL surgery and found there is very little difference between a single and double-bundle ACL reconstruction for the vast majority of patients.
The most important technical issue is to have the ACL reconstruction graft placed in the correct position. On the tibia (shinbone), the tunnels should be in line with the posterior margin of the anterior horn of the lateral meniscus. On the femur (thigh bone), the reconstruction tunnel should be placed at the midpoint of the attachment bundles of the anteromedial and posterolateral bundles, with the main portion of the reconstruction tunnel being posterior to the lateral intercondylar ridge (resident’s ridge).
A large number of ACL reconstruction graft failures are in those patients who have the graft placed too posterior (central) on the tibia with an inability to control rotation of the knee or too anterior on the femur (anterior to resident’s ridge) or too central on the femur (effectively only reconstructing the anteromedial bundle), which leads to either stretching of the reconstruction graft or failure to control knee rotational laxity.