How the Knee Works

There are four primary ligaments in the knee: medial collateral ligament (MCL), anterior cruciate ligament (ACL), lateral collateral ligament (LCL) and posterior cruciate ligament (PCL). Together they hold the bones of the joint in place and keep the knee stable.

Cruciate ligaments are found inside the knee joint. They cross each other forming an “X” with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the back and forth motion of your knee.  The ACL runs diagonally in the middle of the knee. It prevents the tibia from sliding out in front of the femur and provides stability to the knee, both front to back and in rotation.  The posterior cruciate ligament is located in the back of the knee.  The PCL keeps the shinbone from moving backwards too far. It is stronger than the anterior cruciate ligament and is therefore injured less often.  Often a posterior cruciate ligament injury occurs in conjunction with injuries to other structures in the knee such as cartilage, other ligaments, menisci and bone.

PCL Injuries

Grade 1 Sprains: The ligament is mildly damaged and slightly stretched, but is still able to keep the knee joint stable.

Grade 2 Sprains: The ligament is stretched to the point where it becomes loose, often referred to as a partial tear.

Grade 3 Sprains: Referred to as a complete tear of the ligament; the ligament has been split into two pieces, and the knee joint is unstable.

PCL tears are often partial tears with the potential to heal without intervention. People who have injured just their PCL are usually able to return to sports without surgery, unless it is a Grade 3 sprain; however, even some grade 3 sprains, patients are able to return to many activities without surgery.

Causes of PCL Injuries

A PCL tear typically requires a powerful force, such as a direct blow to the front of the knee.  PCL injuries are often seen after traumatic falls, auto accidents, or resulting from direct blows in contact sports such as football.

Symptoms of a PCL

  • Pain
  • Swelling and stiffness
  • Difficulty walking
  • Feeling of instability

Treatment for PCL Injury

Injury to only the posterior cruciate ligament most often does not require surgery. Nonsurgical options include rest, ice, gentle compression, elevation, bracing, and physical therapy.

If other ligaments are injured in addition to the PCL injury; surgery may be required to restore function and a pain free existence.   Surgery for ACL/PCL repair is almost always accomplished arthroscopically using small incisions, which means less pain and a faster recovery time for the patient than with an open surgical repair.