Posterior Cruciate Ligament Injuries

In order to better understand posterior cruciate ligament (PCL) injuries, it is important to understand basic knee anatomy and the function of the PCL. Please review the section on knee anatomy before reading this section.

Posterior Cruciate Ligament

What is the function of the posterior cruciate ligament?

The PCL helps stabilize the knee by preventing excessive backward movement of the shin bone (tibia) on the thigh bone (femur). PCL injuries can go undetected because unlike anterior cruciate ligament (ACL) injuries they are less likely to cause problems with instability. However, if the PCL is significantly damaged or if other knee ligaments are damaged in addition to the PCL, the knee can feel “unstable” or it may “give out”. Depending upon the type and severity of the injury, other structures in the knee may be damaged in addition to the PCL.

There may be injuries to the “shock-absorbing” cartilage (menisci), the collateral ligaments (MCL or LCL), the anterior cruciate ligament (ACL) or the bones of the knee. The degree of injury to the PCL may vary. In some cases, the PCL may only be partially torn or in more serious cases the PCL may be completely torn. Unfortunately, the PCL does not have the ability to completely heal once it is injured.

What causes posterior cruciate ligament injuries?

The PCL may be injured in a number of ways but the most common mechanism described is a direct blow to the front of the upper shin bone (tibia). This forces the tibia backwards on the thigh bone (femur) resulting in damage to the PCL. A twisting injury or sideways blow to the knee can also damage the PCL as can extreme over flexion (bending) or over extension (straightening). When the PCL is injured by itself there is usually not much indication that there is a significant ligament injury. If there are other injuries to the knee or the injury to the PCL is severe the knee can be painful, swollen and/or feel unstable. Occasionally when the PCL is damaged the knee may “give out”, “give way”, or “collapse” when subjected to twisting or rotational forces particularly if other knee ligaments are also injured.

How do you detect posterior cruciate ligament injuries?

Examination techniques that detect forward-backward (anterior-posterior) looseness in the knee are effective in detecting PCL tears. Tests that detect rotational or sideways looseness can help detect other ligament injuries. X-rays are often done at the time of the injury to make sure the bones of the knee are not broken. A special machine called an arthrometer or other tests such as Magnetic Resonance Images (MRI) are occasionally used to help diagnose PCL tears in difficult cases. Research has shown that premature “wear and tear” arthritis (osteoarthritis) can develop in individuals with PCL injuries. A bone scan is a special test that can help detect and monitor the development of osteoarthritis.

Henry Vandyke Carter, Public domain, via Wikimedia Commons

How do you treat a posterior collateral ligament injury?

The treatment of PCL injuries depends on the severity of the injury and other associated injuries. Each treatment plan should be individualized. Initially, protection (by use of crutches and/or a rehabilitation brace), rest, ice, compression and elevation (PRICE) of the injured knee will help reduce pain and/or swelling.

After a PCL injury the long term goal is to return the individual back to their previous level of activity. Achieving this goal will depend on the function and stability of the knee. A general knee rehabilitation program which includes strengthening exercises, flexibility exercises, aerobic conditioning, technique refinement and proprioceptive (biofeedback) retraining is the most important factor in improving knee function and stability. Some people with PCL injuries report an improved sense of stability when wearing a PCL brace, particularly if they have had an injury to another knee ligament. Rarely, surgery to reconstruct the PCL is required to improve knee stability.

Even with the most ideal treatment, the knee may never be as “normal” as the uninjured knee and modification of activity may be required. Furthermore, some research has identified that individuals who have PCL injuries are at greater risk for patellofemoral pain (knee cap pain), further knee injuries and premature “wear and tear” arthritis (osteoarthritis) of the knee joint. However, doctors and physiotherapists trained in treating PCL injuries can outline an individualized treatment plan which will maximize the long-term function and stability of the knee.

To read more about PCL braces click here. Please visit the links section for additional information on PCL injuries. Links have been provided to other websites as well as online medical journals. Other knee injury topics can also be accessed.