The Posterior Cruciate Ligament (PCL) is one of a pair of ligaments that are found in the middle of the knee. The PCL receives little attention when compared to its brother the anterior cruciate ligament but it is very important for knee stability. The PCL originates on the posterior (back) tibia (shin bone) and attaches on the anterior (front) femur (thigh bone). The PCL prevents the tibia from displacing backward on the femur. It also provides rotational stability to the knee joint.
The PCL is injured at a rate far less than the ACL. A PCL injury, however should not be discounted as a trivial injury. The PCL is often injured in conjunction with other ligaments such as the MCL. This results in multidirectional instability as shown in the graphic.
Mechanism of Injury
The PCL is most often injured by a blow to the front of the tibia. Most PCL injuries are a result of falling on the shin or the front of the shins being struck by an automobile dashboard during a wreck. This causes the tibia to move posteriorly, stretching or tearing the PCL. In the athletic arena, a PCL tear is usually the result of a hyperextension injury. For example, a football running back hit low from the front while being tackled from behind, the foot sticks in the turf as the forces of the tacklers cause the knee to hyperextend.
As with any injury evaluation, begin with a thorough history of the injury. The clinical exam should include an evaluation of all of the knee’s structures (medial & lateral collateral ligaments, ACL, PCL, menisci, and patello-femoral joint). The sag test for PCL integrity as well as the posterior drawer should be used to determine tibial translation. Be sure to evaluate the injured knee from the side as well as front to determine the amount of posterior sag. A view from the front only can be deceiving and cause the clinician to misdiagnose the problem. The picture on the bottom of the previous page shows a positive posterior drawer sign.
Symptoms of a PCL tear can vary relative to the amount of instability and degree of ligament laxity. The PCL is located outside the knee joint, therefore a large hemarthrosis (blood in the joint) is not likely. Swelling will usually be noted in the popliteal (back of the knee) space and ecchymosis (bruising) may become evident 24 - 36 hours after the injury in the same area, possibly extending down the calf. The other major symptoms of a PCL tear include acute pain and chronic instability.
If chronic instability does exist, this must be addressed by an orthopaedic surgeon. Instability of the knee will lead to premature degenerative arthritis, possibly resulting in the need to have a total knee replacement in the future. The orthopaedic surgeon may order an MRI to confirm the PCL damage. The MRI shows a tear of the PCL. (Note the colored MRI is computer enhanced.) The clinical examination combined with the MRI will assist in the determination of appropriate treatment.
RehabilitationProper Rehabilitation begins with control of pain, swelling, regaining normal range of motion. As swelling and pain decrease strength training should be instituted. Strength training should focus on the quadriceps muscle group. The quads will provide an anterior pull on the tibia, removing stress from the PCL. This is the opposite of ACL rehabilitation.
As strength and function increase, more aggressive strength training should be instituted. These exercises should be functional in nature. Examples are agility training (cariocas, zig-zag running, low intensity bounding) and endurance training. The degree of intensity and difficulty should be gradually increased as proprioception and functional ability improve.
Return to Participation
Return to participation will be determined by the treating orthopaedic physician. Return will be based on attaining normal range of motion, normal strength, normal proprioception and functional ability. The physician may choose to brace the affected knee to control undue stress on the affected joint. This brace is designed to prevent extraneous rotation. Preventing incidents of “giving –way” will help to decrease the likely hood of degenerative arthritis developing as the athlete ages.
If reconstruction of the PCL is determined to be necessary, the athlete should take care to follow the prescribed rehabilitation protocol to ensure a positive outcome. Rehab after a PCL reconstruction is more important to a positive outcome than the surgery to repair the injured ligament. If the athlete does not regain strength, motion, and functional abilities the repair will be compromised. Proper rehabilitation is a must!
©2000 - 2009 David Edell
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Last Update for AthleticAdvisor.com: 10/24/2009 12:09:35 AM