1. The posterior cruciate ligament (PCL) is the counterpart to the anterior cruciate ligament (ACL).
The PCL originates from the anterior medial wall of the intercondylar notch. It courses backwards (posterior) to insert upon the tibia. The ACL and PCL cross in the middle of the knee, which is why they are called "cruciate" ligaments. The PCL prevents posterior translation of the tibia (shin) on the femur, and is the primary stabilizer in that direction.
2. It usually results from a forceful trauma.
Anything that causes the tibia to be forced posterior may cause a PCL tear. Falling directly on the proximal tibia or hyperextending the knee in sports can do it. Dashboard injuries in car accidents can also cause PCL tears. The front of the tibia strikes the dashboard while the rest of the body is still moving forward. This again forces the tibia backward. The PCL may also be involved in multi-ligament knee injuries. It can occur in conjunction with ACL, MCL or LCL tears. Tears involving the PCL and LCL usually involve the posterolateral corner (PLC) in between.
3. It is less common than an ACL tear.
The PCL is a thicker, more stout ligament than the ACL. Whereas the ACL is approximately 7 to 12mm thick, the PCL averages 13mm in thickness. iomechanically, it has been shown to be stronger than the ACL. Also, the quadriceps help to resist posterior translation of the tibia, which also contributes to its less-frequent tearing.
There are also less injuries associated with PCL tears than with ACL tears. Whereas 50 percent of ACL tears will have concomitant meniscal or articular cartilage injuries, meniscal tears and bone bruising are seen infrequently in isolated PCL tears.
4. Most PCL tears can be treated with rehabilitation.
There is still some controversy with regard to treating isolated PCL tears. Grade I and II tears can be treated with a short period of bracing and crutches, followed by a course of physical therapy. Isolated Grade III PCL tears are a bit more controversial. Typically, there is a short period of immobilization or splinting for a few weeks, followed by physical therapy to strengthen the quadricep muscles. Remember, the quadriceps help to pull the tibia anterior, which helps to protect the PCL. The natural history of isolated PCL tears seems to suggest that residual laxity is fairly well-tolerated. A 1986 study by Bergfeld from the National Football League Combines found that approximately 2 percent had PCL-deficient knees. Yet they were still able to function at the elite level.
5. Sometimes, surgery is indicated.
If there is symptomatic instability of the knee, surgical reconstruction should be considered. There are various ways of reconstructing the PCL, including all-arthroscopic and arthroscopic-assisted techniques.
