Surgeons from Korea offer this report on a rare injury in children. They had six cases of a knee injury called peel-off injury. Trauma from sports injuries or falls resulted in the posterior cruciate ligament (PCL) tearing away from the tibia (lower leg bone), one of the places where it attaches.
The posterior cruciate ligament is one of two ligaments that criss-cross to form an X-shape inside the knee. Together, these ligaments hold the knee stable and keep the bones from shifting too far apart. The posterior cruciate ligament is designed to prevent the tibia from sliding too far back underneath the femur (thigh bone).
Another term for this type of injury is tibial avulsion of the PCL. In all six cases, boys between the ages of 12 and 13 suffered a direct blow to the upper portion of the tibia (just below the knee) while the knee was bent. Some of these injuries occurred during soccer while others happened during basketball, dodge ball, or as a result of a fall.
This report is important, not only because these injuries are relatively rare, but because surgical repair is tricky. In all six cases, the ligament peeled away from the bone cleanly. In other words, the bone was left intact. Sometimes, the ligament pulls away with a piece of bone still attached to it. Reattachment and fixation with a screw is easier when the ligament avulses (ruptures) along with a bit of bone. The surgeon can anchor it back down where it belongs by using a screw through the bone fragment.
With a peel-off injury, it is necessary to use multiple sutures without piercing any of the nearby nerves, blood vessels, or growth plate. Disturbance of the growth plate (called the physis) by drilling holes through it to anchor the sutures can lead to deformity. Drilling tunnels across the physis can also cause the growth plate to close early on that side. The result can be a difference in leg length from one side to the other.
Given the success of their technique, the authors wrote this article to describe the surgical procedure. With drawings and arthroscopic photos taken during the procedure, they show the injury and the proposed surgical repair.
The postoperative program of physical therapy started right after surgery. The children were kept in a hinged, long-leg brace that was kept locked in a fully extended position for four weeks. This approach of immobility is designed to protect the healing ligament.
At the end of the four-week period of time, the brace was unlocked and passive movement was allowed. The child was allowed to put gradual increasing amounts of weight on the leg until the brace was removed eight weeks after surgery. All activities were resumed as the child was able to perform them. Sports activity was allowed when motion and strength were within normal limits.
During the follow-up period, all six children had full knee range of motion without any sign of instability. Function was rated as normal or near normal as measured by the International Knee Documentation Committee (IKDC) evaluation and the Lysholm knee scoring scale. Follow-up was at least two years long. Some children were followed for a full five years.
The authors conclude that children with peel-off injuries of the posterior cruciate ligament can be treated safely and effectively with surgery to repair the damage. Fixation of the ligament stump (ruptured end separated from the bone) can be done arthroscopically using multiple sutures.
In the case of one child where the stump was split, repair was unsuccessful and the ligament had to be reconstructed instead. Everyone in the study will continue to be followed in order to determine long-term results of this treatment.