What is the Posterior Cruciate Ligament (PCL)?
The PCL is a ligament in the middle of the knee that holds the femur (thigh bone) on top of the tibia (shin bone) by preventing the femur from sliding forwards. Along with the ACL, it keeps the knee motion stable during bending and straightening.
What causes a PCL rupture?
The PCL can be ruptured when the top of the tibia is forced backward. This can happen due to a blow to the knee when bent (the classic examples are the knee cap smashing into the dashboard in a head on car accident, and the bent knee hitting down on to the ground in a rugby scrum). It can also happen when the knee is forced into hyperextension (knee pushed back more than straight). Occasionally it happens with a relatively minor injury (such as missing a step or kerb)
What problems can a PCL rupture cause?
Initially at the time of injury there is pain and swelling. There may be a feeling of instability (feels like it will give way beneath you), but that is not always the case.
If the PCL rupture is the only injury (isolated PCL rupture) the pain and swelling settles will usually settle over days or weeks. Down the track the knee may become painful or swollen with exercise, or there may be vague feelings that it is not quite stable or not quite right. It is unusual for PCL rupture to cause the knee to collapse completely.
How is PCL rupture treated?
Isolated PCL rupture is initially treated like other injuries with rest, ice, compression and elevation (RICE) until the swelling settles. It is safe to bear weight on the knee, but crutches can help with early pain. Range of motion exercises and gentle physiotherapy can begin within days. As soon as comfort allows, exercises to strengthen quadriceps and hamstring muscles will help prevent the knee feeling unstable.
If there are other ligaments injured at the same time (multiple ligament injury, or knee dislocation) then the PCL reconstruction surgery is often required.
What is PCL reconstruction?
Sometimes strengthening program is not enough to make the knee stable when patients get back to sports or physical work. In that case, surgery (PCL reconstruction) can reconstruct the ligament by putting a new ligament in its place. The new ligament can be made from a piece of tendon taken from elsewhere the patient’s own leg (hamstring, quadriceps or patella tendon) or from synthetic material (LARS ligament). This is done using knee arthroscopy through small incisions. PCL reconstruction is also often required if multiple ligaments are injured.