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:
History. Your doctor will ask what you were doing when the injury occurred, such as traveling in a car or playing a sport. He or she will also ask:
- If your knee was bent, straight, or twisted when it was injured
- How your knee felt after the injury
- If you’ve had any symptoms since you were injured
Physical examination. In a common test for PCL injuries, you lie on your back with your knee bent. Your doctor then examines your knee and presses against your upper shin. Abnormal knee movement during this test suggests a PCL injury.
You may also be checked with a device called an arthrometer. This presses against your leg to measure the ligament’s tightness.
Your doctor may also ask you to walk. An abnormal walking motion may point to a PCL injury.
Imaging. X-rays can provide information about a PCL injury. They can detect pieces of bone that may have broken loose from the injury.
Magnetic resonance imaging (MRI) is a common way to create images of a PCL tear. An MRI can find the exact location of a tear.
With chronic PCL injuries, a bone scan may be needed to look for damage to the bones.
Home Treatment of a Posterior Cruciate Ligament Injury
For initial treatment of a PCL injury, the approach known as PRICE may be helpful. This includes:
- Protecting the knee from further injury
- Resting the knee
- Icing the knee for short periods with cold packs
- Compressing the knee gently, such as with an elastic bandage
- Elevating the knee
A pain-relieving medication may also be needed for knee pain.
Nonsurgical Treatment of Posterior Cruciate Ligament Injury
You can recover from some posterior cruciate ligament injuries without surgery.
Cases that may not require surgery include:
- Acute grade I or II injuries when no other knee ligaments are injured
- Newly diagnosed chronic injuries that only affect the PCL and aren’t causing symptoms
Some people need to go through physical therapy after a PCL injury. This rehabilitation may be necessary with or without surgery.
Rehabilitation may include:
- Using crutches at first, then gradually walking with more weight on the knee
- Having a machine or therapist move your leg through its range of motion
- Temporarily wearing a knee brace for support
- Strengthening your thigh muscles to help make the knee more stable
- Walking or running in a pool or on a treadmill
- Specific training needed for a sport
Surgery for Posterior Cruciate Ligament Injury
Patients who may be more likely to need surgery include those who have:
- PCL injuries in which pieces of bone have torn off and become loose
- Injuries involving more than one ligament
- Chronic PCL looseness that causes symptoms, especially in athletes
If a piece of bone is torn off, a surgeon may fasten the bone back into place using a screw.
Surgery for a torn PCL requires replacing it with new tissue rather than stitching together the torn ligament. The ligament may be replaced with:
- Tissue from a deceased donor
- Piece of tendon moved from somewhere else in the body, such as the back of the thigh or heel.
The operation is sometimes done as an “open” surgery. This requires a large incision in the knee.
A less-invasive option involves a tool called an arthroscope. The surgeon uses smaller incisions.
After surgery, the length of time needed for rehabilitation can range from 26 to 52 weeeks.