ACL (Anterior Cruciate Ligament) Repair
Introduction
Anatomy
Cruciate ligaments (also cruciform ligaments) are pairs of ligaments arranged like a cross in the knee joint. Cruciate ligaments of the knee are the Anterior cruciate ligament(ACL) and the Posterior cruciate ligament (PCL). These ligaments are two strong, rounded bands that extend from the head of the tibia to the intercondyloid notch of the femur. The ACL is lateral and the PCL is medial. They cross each other like the limbs of an X. The ACL and PCL remain distinct throughout and each has its own partial synovial sheath.
Injury to the anterior cruciate ligament (ACL) can be devastating. It generally occurs in younger patients, and misdiagnosis, delayed diagnosis, recurrent injury, and improper surgical technique may leave a teenage athlete with a knee that is destined to develop premature arthritis. Fortunately, perspectives on the management of ACL-injured knees are changing.
Function
Relative to the femur, the ACL keeps the tibia from slipping forward and the PCL keeps the tibia from slipping backward.The ACL originates from the medial and anterior aspect of the tibial plateau and runs superiorly, laterally, and posteriorly toward its insertion on the lateral femoral condyleThe ACL consists of individual fiber bundles, named for their insertion points on the tibial footprint. The larger anteromedial (AM) bundle inserts anteromedially on the tibial side and originates more proximally on the femoral side than the posterolateral (PL) bundle, which is posterolateral relative to AM bundle.
Studies indicate that the AM bundle tightens in flexion while the PL bundle relaxes; in extension, the PL bundle tightens while the AM bundle relaxes… In extension, their insertion points are vertical to each other, but with the knee in 90 degrees flexion, the insertion points are horizontal to each other. Likewise, the bundles themselves shift from parallel orientation in extension to crossed orientation in flexion.
Mechanism of Injury
ACL injuries can have contact or, more frequently, noncontact mechanisms of injury. They may occur with internal or external rotation maneuvers. Noncontact injuries generally involve a deceleration, change-of-direction maneuver. Patients usually recollect a sensation of the knee buckling and collapsing to the ground.An audible pop or tearing sensation is heard in 80% of acute ACL injuries.
The knee frequently develops a hemarthrosis within 3 hours, but in some patients there may be a gradual onset of swelling over 24 hours. In an acutely injured knee, meniscal tears occur more frequently laterally than medially) In the chronic setting, medial meniscal tears occur more frequently.
Treatment
Traditionally treatment of ACL tear involve new reconstruction th tendon grafts from hamstrings, patellar tendon etc. Single-Bundle ACL reconstruction, a graft is used to basically replicate the positioning of the AM bundle. The Double-Bundle technique uses two separate grafts to replicate the positioning of both the AM and the PL bundles. Because the AM bundle makes a greater contribution to anteroposterior knee stability, while the PL bundle makes a greater contribution to rotational stability, a double-bundle technique may be better able to restore normal knee kinematics.