The posterior cruciate ligament (PCL) is a ligament within the knee. Ligaments are tough bands of tissue that connect bones.
The PCL -- similar to the anterior cruciate ligament (ACL) -- connects the thigh bone (femur) to your shin bone (tibia). Although it is larger and stronger than the ACL, the PCL can be torn.
PCL tears make up less than 20% of injuries to knee ligaments. Injuries that tear the PCL often damage some of the other ligaments or cartilage in the knee, as well. In some cases, the ligament can also break loose a piece of underlying bone.
Causes of PCL Injuries
PCL injuries are often due to a blow to the knee while it's bent. Common causes include:
- Striking the knee against the dashboard during an auto accident
- Falling on the knee while it's bent
Sports are a common cause of PCL injury. These injuries are especially common in:
An injury to the PCL can cause mild to severe damage. Doctors classify PCL injuries in these groups:
- 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.
PCL problems can be acute or chronic. Acute PCL problems are due to a sudden injury. Chronic PCL problems involve an injury that develops over time.
Symptoms of PCL Injury
Most people don't feel or hear a "popping" sensation in the knee after a PCL injury. This is more common with an injury to the ACL.
After a PCL injury, people often think they only have a minor knee problem. They may try to go on with their usual activities. However, symptoms that can develop include:
- Swelling (mild to severe)
- Knee pain
- Wobbly sensation in the knee
- Trouble walking or bearing weight on the knee
Over time, a PCL tear can lead to osteoarthritis in the knee.
Diagnosing PCL Problems
To diagnose a PCL injury, a doctor may take these steps: