What is a Torn Posterior Cruciate Ligament?
The knee has four ligaments, which are tough bands of tissue that connect bones and muscles. These ligaments provide flexibility and stability as your knees move:
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
- Medial collateral ligament (MCL)
- Lateral collateral ligament (LCL)
The ACL and PCL connect your thighbone (femur) to your shinbone (tibia) on the inside of the knee joint. The ACL is behind the kneecap, and the PCL crosses with it to form an “X.” The PCL is the major stabilizing ligament of the knee that keeps the tibia (shinbone) from going too far backwards. The PCL is stronger than and twice as thick as the ACL. It is not injured as often, but it can be torn or sprained. PCL injury is a common sports injury. A PCL injury may happen on its own or with other ligament injuries. It can range from being overstretched to being completely torn. Your symptoms will depend on how badly your PCL is hurt. Injuries are classified by degrees or grades:
- Grade 1: Limited damage with only microscopic tears
- Grade 2: Partial tear of the ligament, leaving a small feeling of instability
- Grade 3: Ligament is completely torn, often along with a sprain of the ACL or other knee ligaments
Your symptoms will depend on the level of your injury. With a grade 1 injury, there is minimal pain, swelling, or instability, and a full range of motion. You may not even notice the sprain. In grade 2, the knee may be painful, swollen, and feel a bit unstable. In grade 3, and with other injuries that involve the other knee ligaments, you may experience any combination of:
- Pain at the front and back of the knee
- Limited range of motion
- A feeling of instability or looseness in the knee
- Difficulty walking
- Possibly cuts or lacerations
If you have a chronic (long-term) PCL injury, you may have knee pain, swelling, or stiffness in the knee. This injury causes discomfort when the knee is partly flexed, such as when you go down the stairs, or aching when walking a long distance. A chronic PCL injury could cause you to feel wobbly in the knee when walking on an uneven surface.
The most common way the PCL is injured is a direct blow to the outside of the shin when the knee is bent. The PCL can also be injured when the knee is rotated and overextended. This situation usually happens during kicking sports like soccer or football, and sports where the knee is under stress, like skiing.
The PCL can also be injured in a car accident when the bent knee hits the dashboard. Other causes of PCL injury include a fast change of direction, a misstep, or a bad landing after a jump.
Diagnosis and Tests
You may be referred to a doctor who specializes in sports medicine or in the bones and connective tissues. The doctor will ask about your medical history as well as how the injury happened. They will test your knee’s range of motion and have you do certain movements to observe what motions cause pain.
Your doctor will also want to use tests to diagnose PCL injury, such as an x-ray, MRI, bone scan, or ultrasound. Your leg will be imaged in different positions, such as standing and flexed. Your doctor may also want to do an arteriogram to check for any damage to veins in the leg.
Treatments & Prevention
Nonsurgical treatment is best for people who aren’t as active or healthy, or for those with a less severe PCL injury. This treatment entails physical therapy programs that can last several weeks to several months. Your physical therapist will design a program that can help you increase movement and strength in the legs and knees while the ligament heals on its own.
- For chronic PCL injury, the treatment is usually physical therapy.
- For an isolated grade 1 or 2 sprain, surgery is not usually needed. Typically, the doctor will put something like a brace on your knee to keep it from moving and have you use crutches for two weeks to protect your knee from bearing weight. As the ligament heals, you will need physical therapy to strengthen the leg muscles.
- For a grade 3 injury, you may be able to treat it with or without surgery. For nonsurgical treatment, your doctor may recommend immobilizing the knee with a brace or cast for 2 to 4 weeks. You will need physical therapy afterward.
- When grade 3 injuries are combined with other injuries, and you are healthy enough, your doctor may recommend surgery.
- Athletes and young, healthy people often want to treat the injury with surgery to begin healing right away and get back to normal activity.
During surgery, the doctor will reconstruct the PCL with tissue from your hamstring, your other knee tendon, or a tissue donor. For the best results, surgery should be done within a few months after the injury. Physical therapy after surgery will help you rebuild strength in your leg and knee.