The PCL is the ligament that prevents the leg bone or shinbone (tibia) from sliding too far backward. The ACL does the opposite and keeps the shinbone from sliding too far forward. While both play a crucial role in the stability of the knee joint, the ACL is more commonly injured than the PCL, primarily because of its size and location. Approximately 20% of ligamentous knee injuries may be related to the PCL. The most common way to injure the PCL is through a direct strike to the knee that forces the tibia backward. An example of this type of situation can be described as falling on the knee while it is in the bent position, or as the knee is coming into direct contact with the dashboard of a car during an automobile accident. PCL knee injuries are considered serious and often go undiagnosed unless a complete tear has occurred.
Symptoms and Diagnosis
A PCL injury will present similar symptoms to that of an ACL injury. The most common symptoms are knee pain, swelling, tenderness, and a decreased range of motion. Instability is not as common with a PCL tear as it is with an ACL tear, but it can occur in some cases and indicates that a severe tear has most likely resulted.
Your physician will perform a thorough physical exam during the initial consultation. He will manipulate the knee and move it into various positions to determine the pain level, range of motion, and overall mobility. The most reliable test to diagnose a PCL tear is through a Posterior Drawer Test. During this exam, your physician may bend the knee and will then push the tibia backwards to see if the PCL is stressed. A clear indicator that a tear has occurred will result if the tibia does in fact slide too far backward. In all cases, your physician will order X-rays to ensure that no bones are broken or otherwise damaged, and an MRI may also reveal any meniscus, or ligament damage. Your physician will then assign a grade to the injury which will range from a Grade 1 injury (partial tear), Grade 2 injury (isolated, complete tear), or a Grade 3 injury which is a full tear of the PCL, as well as usually involves another ligament, typically the LCL and associated structures of the “posterolateral corner (PLC)” of the knee joint.
Surgical reconstruction of the PCL is somewhat controversial. Most surgeons believe that surgery should be reserved for Grade 3 PCL injuries which usually occur in association with injuries to other structures, which also require repair. The vast majority of cases, patients who have a symptomatic PCL tear limiting mobility and function also have a posterolateral corner injury, or less commonly a posteromedial injury or other associated injuries. Thus, surgery will be needed. In general, most PCL injuries that involve a partial tear, or isolated tear, can be treated without surgery and a thorough physical therapy program focusing on quadricep strengthening and full range of motion, and sometimes a knee brace will be implemented.
During PCL reconstruction surgery, an allograft (donor tissue) is usually recommended to reconstruct the ligament and associated injuries, and restore knee stability. Your physician is able to perform the PCL reconstruction via an arthroscopic method in almost all cases; however, because the collateral ligaments are on the outside of the joint, open surgery is usually required for collateral ligament injuries.
Following PCL reconstruction surgery, patients will be required to wear a brace for approximately 3-6 months. An extensive rehabilitation program will be prescribed. Therapy will be a progressive process and will initially focus on returning motion back to the injured knee and surrounding muscles, while protecting the healing ligament. Following this phase, an active and progressive strengthening program will help to gain strength and control to the knee and leg allowing patients to slowly return to normal activities.