Inside the knee there are two major ligaments that criss-cross each other to hold the knee in place. These are the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL).
Injuries of the ACL are common and treatment for this problem is well known. Less often, the PCL is torn or ruptured requiring evaluation and treatment. In this article, the anatomy, function, and changes that occur when the PCL is damaged are presented. Testing and treatment are also included.
The PCL has a stabilizing force on the knee joint. It helps hold the tibia (lower leg bone) in place and keeps it from sliding backwards. This movement is called posterior translation. The most common cause of PCL tears is trauma. A high-energy force against the knee during a car accident or sporting event is often reported.
Diagnosing PCL insufficiency can be challenging. The patient often doesn’t remember the injury. Symptoms are vague. There may be mild knee pain and stiffness. In the acute phase, the pain is in the back of the knee. Later, there can be pain in the front of the knee.
The physician relies on the history, exam, and specific tests to make the diagnosis. X-rays and MRIs are more helpful in the acute stage. There are also several clinical tests that can be done to look for PCL involvement.
The posterior drawer test is used most often. The posterior sag test and the quadriceps active test are also used. All three tests are described in detail. Additional tests may be needed if there are other soft tissues that have been disrupted. The examiner uses the uninjured knee as a guide when conducting each test.
Treatment for low-grade PCL injuries is nonoperative. Bracing, physical therapy, and time are the main management tools. If the symptoms do not resolve or if there’s a high-grade injury, then surgery may be needed. The goal of surgery is to stabilize the knee and reduce joint laxity (looseness).
Research is ongoing trying to find the best surgical technique for PCL repair or reconstruction. Results with current methods have been less than satisfactory.
Long-term studies are needed to see if surgery even makes a difference 10 or 20 years later. It may be that a rehab program is all that’s needed to restore PCL function and knee stability.