The posterior cruciate ligament (PCL) is one of two ligaments that sit in the intercondylar notch with the other ligament being the anterior cruciate ligament (ACL). Above you will see an acute PCL tear (LEFT) compared to the 3.2 year (RIGHT) post injury MRI which shows the PCL healed (dark black structure in the middle is the PCL).
PCL tears are a less common injury to have compared to the ACL, but often an overlooked or misdiagnosed injury. The most common ways to tear the PCL is from motor vehicle accident when the knee hits the dashboard, or when one falls on a bent knee and the foot is plantar-flexed or pointed. There are conflicting opinions on the best way to treat these injuries: surgery to reconstruct the ligament or leave it alone and rehab the knee. A few studies look at the non-operative treatment for acute PCL injuries. Laxity of the knee means the ligament is too loose. Most physicians agree that PCL injuries that occur along with other ligament injury should have a PCL reconstruction, or if there is PCL laxity of a 2+ or more.
Our philosophy in treating isolated PCL tears, or PCL tears that occur along with other knee ligament tears, is a nonsurgical approach. If the MCL (medial collateral ligament) is lax then the patient is casted, 30 degrees flexed, for one week, which will allow the MCL to heal, and if the PCL is torn, it will heal as well. We treat ligament injuries based on the individual structure’s ability to heal. The ACL and the lateral side do not heal whereas the PCL and the MCL will heal if stabilized appropriately. We have not done a PCL reconstruction in over 20 years and all PCL injuries will heal with an endpoint but with some laxity compared to the opposite knee. Even PCL with 3+ laxity will heal with a 1-2+ laxity and an endpoint on physical exam. Dependent on the individual’s level of activity and function, majority of patients have no limitations by this amount of laxity in the joint. Tewes et, al, COOR, 1997, performed a study of 13 isolated PCL injuries with MRI at acute and follow up visits. There was return of continuity in 10 out of 13 isolated PCL injuries. The three patients who had discontinuous PCLs had a 2+ posterior drawer test. Shelbourne et al, Am J Knee Surg 1999, published a study on PCL heals whether isolated or in conjunction with other ligaments. An MRI scan performed at acute injury, and at 3.2 years post injury with 23-isolated PCL tears, 12 PCL/MCL, 5 PCL/ACL and lateral or medial side injuries. The results showed 21 of the 23 isolated PCL tears healed non-operatively, and all the PCL with MCL injuries healed. With the PCL/ACL injuries, the PCL healed but the ACL did not. There were two PCL/MCL/ACL injuries and the PCL and the MCL healed but the ACL did not. There was one PCL/MCL/lateral side with a healed PCL and MCL, but the lateral side did not heal. So, the PCL does have with some laxity but a definite endpoint with posterior drawer examine.
We also did a minimum 10-year follow up study looking at both subjective and objective results as a continuation of the short-term outcome study. Sixty-eight patients were contacted at a minimum of 10 years after injury with a focus on physical examination and radiographs for presence of osteoarthritis. The results were all patients completed the subjective surveys with a mean time of 17.6 years after injury. Forty-four patients were available for objective evaluation with a mean of 14.3 years post injury. There was no difference in stability or total scores between patients who returned for both objective and subjective evaluation, and patients who completed a subjective survey alone. There was no loss of range of motion. Quad strength mean was 97% and hamstring strength mean was 93%. The radiographs showed 59% had normal x-rays, 30% had nearly normal, 9% were abnormal and only 2% were severely abnormal. The patient’s subjective scores with CKRS (Cincinnati Knee Rating System) total was a mean 81.3 and the IKDC (International Knee Documentation Committee) total was a mean of 73.4. These scores are out of 100 points possible. Whether or not there was a Grade 1, 1.5 or 2 laxity, there was no statistically significantly difference for total scores over time when looking at PCL laxity grade.
Most studies report about a 50% success for restoring normal stability with PCL reconstruction. When comparing the overall success rate of doing surgery with the non-operative treatment, one must ask if, with its risks, surgery provides a better outcome than non-operative treatment.