The posterior cruciate ligament (PCL) is a tough fibrous band of tissue that works within the knee. Together with the anterior cruciate ligament (ACL), the two bands criss-cross each other inside the knee in order to provide stability. There is also the medial collateral ligament and the lateral collateral ligament which sit on the middle side of the knee and the outer-side of the knee, respectively. Together, these ligaments connect the femur to the tibia, forming the knee joint. It is very important to be mindful of the health of these ligaments since damage to these tissues can cause severe pain and affect further usage of the knee. While each of these four ligaments is crucial to the function and stability of the knee, we will specifically be addressing issues of the PCL for this blog post. These issues include, risks present to the ligament, ways to prevent injuries, treatment for injuries, and of course the PCL injuries themselves.
An Overview of PCL Injuries
The PCL works essentially as an elastic anchor, keeping the tibia from moving too far back in relation to the femur. The properties of this ligament ensure this capability. The PCL is both strong and flexible. It is not without limitations however and when too much pressure is put on the PCL it can be stretched or torn. This type of injury to a ligament is known as a sprain. One of the most common causes of this sprain is a forceful impact to the front of the knee while it is flexed (bent). One main culprit of this is automobile accidents. It is highly likely if you are sitting in the passenger’s side of a vehicle when a collision occurs, that your knee or both will hit the dashboard causing a PCL injury. Sports also cause many PCL injuries. It is easy to sustain a PCL sprain for instance, if you are running down the football field and get “chop-blocked”. It happens very often at all levels of play. Non-contact sports such as basketball and soccer are also full of risks to the knees. Even the seemingly simple movement of a golf swing can cause a PCL injury through the twisting motion of the leg as the player follows through. While PCL injuries caused by twisting are more rare, it is important to be mindful of the risks present. And while the risks are plenty they can be mitigated by:
- Stretching. This is the best way to make sure you are ready for physical activity. Going into a work-out without warming up first increases your chances for a PCL injury severely.
- Strengthening the muscles of the leg. Strong healthy muscles will provide some protection and house the knee and its ligaments more securely.
- Don’t do too much too fast. It’s important to know your limits and work within them to avoid injury. Raise difficulty gradually to improve safely.
- Level the playing field, literally. It’s important when playing sports or engaging in other physical activities to remove potential obstacles from the area that could cause you to trip or twist your legs at an odd angle. Sticks, rocks, or your water hose that you forgot to put away are all potential hazards that could ruin your day!
Symptoms of a PCL Injury
If you suspect that you have sustained a PCL sprain it is crucial to look for the symptoms:
- The knee will occasionally give out or feel “loose”. Swelling also accompanies this loss of stability.
- Pain in the back of the knee, especially when you crouch or kneel.
- Pain in the front of the knee while running, especially when you attempt to slow down.
It is possible to have a sprain and not realize it because the symptoms can be subtle for minor PCL injuries. It’s very hard to miss the symptoms of the more severe sprains however.
Classifications of PCL Injuries
Like any other ligament of the body, PCL sprains are classified according to a traditional grading system:
- Grade 1-This is a mild injury that causes only microscopic tears in the ligament. While these small tears can bend the PCL out of shape, they do not significantly affect the knee’s ability to bear weight.
- Grade 2 (moderate)-The PCL is partially torn and the knee becomes unstable. At this level expect the knee to give out periodically while standing and walking.
- Grade 3 (severe)-The PCL is completely torn or is separated at its end from the bone that it normally anchors. At this point the knee is very unstable and cannot bear your body weight. It usually takes a tremendous force to cause such an injury, so a grade 3 sprain is often accompanied by damage to the other ligaments of the knee.
In general, for all grades of PCL injuries, the initial treatment is to follow the RICE rule. That is:
- Rest the joint to prevent further injury.
- Ice the injured area to reduce swelling.
- Compress the joint with an elastic bandage.
- Elevate the leg when at rest.
The doctor may also recommend a non-steroidal anti-inflammatory drug (NSAID) to relieve minor pain and swelling. After initial treatment with the RICE method, further treatment of a PCL injury depends on the severity.
- Grade 1 and Grade 2 PCL injuries: Your knee will be splinted in a straight-leg position. You will also begin a rehabilitation program that is designed to gradually strengthen the muscles surrounding the knee. This will improve support of the joint and help prevent further injury to the knee.
- Grade 3 PCL injuries: At this Grade surgical reconstruction is recommended. If the PCL has been pulled and detached from its anchor point, it can be reattached with a screw. If the PCL has been torn completely it can be reconstructed using a piece of your own tissue (autograft) or a piece of donor tissue (allograft). With an autograft the surgeon typically uses a piece of tendon taken from one of your large leg muscles. These operations are done using arthroscopic (camera-guided) knee surgery which is minimally invasive. The surgeon will only make small incisions that cause less scarring than traditional surgery. After surgery you will wear a long leg brace and begin a rigorous rehabilitation program to strengthen the leg.
The duration for a PCL injury also depends on the severity of the sprain, but typically full recovery is achieved between 4 to 12 months.
If your knee exhibits signs of a knee sprain it should be a priority to consult with your doctor to figure out if you have a PCL injury. A diagnostic examination of the knee will begin with your doctor maneuvering your knee in ways to test the strength of the PCL and see if your tibia slides back when the knee is flexed. If the doctor suspects a PCL sprain an x-ray exam will be ordered. While soft tissues aren’t especially visible in an x-ray, it is possible that your PCL will pull a piece of bone off from the anchor point. This “floating” fragment of bone is visible with an x-ray and is a tell-tale sign of a Grade 3 sprain. Further imaging will likely be ordered in the form of an MRI exam. An MRI is especially helpful in visualizing soft tissue injures such as a PCL sprain. After this your doctor will discuss the best treatment options for your injury and come up with a plan best suited to get you back to your regular activities as quickly and safely as possible.
Coastal Orthopedics is an excellent choice for treatment of all types of bone and joint injuries, such as a pesky PCL sprain. Feel free to call and set up an appointment so our talented and knowledgeable staff can help get you back to a healthy and active lifestyle!