Knee Arthroscopy
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.
Meniscus - Menisectomy / Meniscus Repair
Meniscus (cartilage) Surgery
The knee has two crescent shaped shock absorbing cartilages, the menisci. The thin, tapered edge is susceptible to tears. The torn part can move in and out of the weight-bearing area and cause locking and/or catching of the joint, and pain. Most often, these tears do not heal spontaneously.
Treatment focuses on preservation of as much functional cartilage as possible, to maintain the shock absorbing function.
The torn, unstable, nonfunctional piece of cartilage is usually removed (Menisectomy) through a 2 – 3mm incision, using a variety of arthroscopic instruments. On occasion, the torn part is repairable (Meniscus repair). Particularly in young and/or athletic individuals. The initial rehabilitation is slower than after removal of the torn part. It is anticipated that repair will lead to better results in the long run.
Meniscus surgery typically takes 30-45 minutes. After excision of the torn part, rehabilitation can be swift, only limited by discomfort. Most people use crutches for the first few days, walk fairly well by the end of the first week, and are ready to consider some exercise by two weeks. The knee remains somewhat painful with activity for several months. A “reminder” that surgery was performed!
After isolated meniscal repair, most often I ask to limit bending of the knee to 45 degrees for six weeks, to protect the repair. Weight-bearing can be initiated immediately.
Posterior Cruciate Ligament
Meniscus (cartilage) Surgery
The posterior cruciate ligament (or PCL) is one of the four major ligaments of the knee. It connects the posterior intercondylar area of the tibia to the medial condyle of the femur. This configuration allows the PCL to resist forces pushing the tibia posteriorly relative to the femur.The PCL is an intracapsular ligament along with the anterior cruciate ligament (ACL) because it lies deep within the knee joint. They are both isolated from the fluid-filled synovial cavity, with the synovial membrane wrapped around them. Along with the ACL which keeps the tibia from sliding too far forward, the PCL helps to maintain the tibia in position below the femur .bone. Posterior cruciate ligament injuries comprise between 3% and 20% of all knee ligament injuries.
Common causes include
Striking the knee against the dashboard during an auto accidentThis occurs when the knee is bent, and an object forcefully strikes the shin backwards. It is called a ‘dashboard injury’ because this can be seen in car collisions when the shin forcefully strikes the dashboard.
Falling on the knee while it’s bent. The other common mechanism of injury is a sports injury when an athlete falls on the front of their knee. In this injury, the knee is hyperflexed (bent all the way back), with the foot held pointing downwards. These types of injuries stress the PCL, and if the force is high enough, a PCL tear will result. These injuries are especially common in football, soccer, baseball, skiing etc.
Classification of PCL injuries
- Grade I : The PCL has a partial tear
- Grade II : The ligament is partially torn and is looser than in Grade I
- Grade III : The ligament is completely torn and the knee becomes unstable
- Grade IV : The PCL is damaged along with another ligament in the knee