Description of PCL Injury
The ligament located on the back and middle of the knee is known as the posterior cruciate ligament, or the PCL. It is one of several ligaments that connect the femur (thighbone) to the tibia (shinbone). The posterior cruciate ligament is the strongest ligament of the knee and thus, it is injured less often accounting for about 3-37% of all knee injuries.
Symptoms of a PCL Injury
- Problems decelerating
- Problems going down stairs and inclines
- Problems twisting, turning, or pivoting
- Pain over the anterior aspect of the knee
A PCL injury is often caused by a powerful force—in many cases from sports trauma. Common causes of this type of injury might be a bent knee hitting something very hard (for example, a dashboard in a car accident or a hockey player hitting the goalpost) or a football player falling on a knee while it is in the bent position.
Dr. LaPrade will assess the PCL injury with a detailed clinical exam, x-rays, kneeling posterior knee stress x-rays, and almost always, an MRI scan to determine the extent of the injury and concurrent injuries to determine the recommended course of treatment for the PCL tear. In general, many isolated PCL injury will heal over time; it is important to diagnose this particular ligament tear early to attempt to get them to heal in a stable position rather than in an elongated and nonfunctional position. While the results of an MRI scan are helpful for an acute injury evaluation, they are not very useful in the case of a chronic injury to evaluate for a PCL tear because they can show an intact posterior cruciate ligament, which may be unstable because it has healed in an elongated position. In this case, stress x-rays are required to diagnose the extent of the tear.
The diagnosis of a PCL injury depends upon assessment of the patient’s posterior knee translation. This involves examining the patient from the side to see if there is any posterior step off, performing a quadriceps active test and also performing the posterior drawer test in neutral rotation. In addition, a patient should have bilateral posterior knee stress radiographs to objectively determine the amount of increased posterior translation on the injured knee.
Degree of Knee Injury
Posterior cruciate ligament injuries are classified according to the amount of injury to the functional ligament:
- Grade I Injury: A small partial tear
- Grade II Injury: A near complete tear
- Grade III: A complete tear whereas the ligament becomes non-functional; usually this occurs with injuries to other knee ligaments (most commonly the posterolateral knee structures)
Most isolated grade I and II PCL injuries should be treated with a non-operative program to include functional rehabilitation of the quadriceps mechanism and the possible use of a jack brace to help reduce the knee into a normal (neutral) position. Dr. LaPrade strongly encourages patients with a partial PCL tear to participate in this rehabilitation program.