Almost everyone has heard of a famous footballer, soccer player or skier having a knee reconstruction. This almost always refers to an ACL or Anterior Cruciate Ligament Reconstruction. PCL or Posterior Cruciate Ligament injuries are uncommon compared to ACL injuries and require surgery far less often.
The posterior cruciate ligament (PCL) gets its name from where it attaches to the tibia or shin bone (posterior to or behind the ACL – posterior means behind and anterior mean in front). The PCL is larger than the ACL and also acts as a knee stabilizer working in almost the completely opposite way than the ACL does. The function of the PCL is to provide stability during twisting or turning movements of the knee and when walking up slopes. It is a large ligament in a reasonably well protected area of the knee and is therefore no often injured. The PCL is technically found outside the knee (extrasynovial) and can heal to some extent (the ACL which sits in synovial fluid rarely heals).
The knee is usually very sore and swollen after the injury but most people are able to walk sooner than they would for an ACL injury. Many people are not aware of exactly what has been injured as the pain is not always felt at the back of the knee. Many doctors are not used to thinking about PCL injuries so the diagnosis may be missed initially. If the PCL injury is combined with another injury, like a posterolateral corner tear, there may be significant bruising and swelling.
Ongoing symptoms vary widely from nothing to pain to the sensation that the knee might give way or buckle (or just not be trusted). They can be minor and only present playing sport, or major, with severe kneecap pain and giving way of the knee when on uneven ground.
Many people are able to return to high level sport after a PCL injury but do have some problems from time to time.
Classification into single versus multiple ligament injuries is important for treatment decisions. Isolated injuries to the PCL may have good results without surgery but multi-ligament injured knees tend to have better outcomes with surgery.
Patients with PCL injuries may present with minimal symptoms with a history of a simple fall months ago or may present after a severe motor vehicle accident with acute bleeding in the knee.
MRI scanning is the best test for a recent PCL injury but is less good for chronic PCL tears. Unfortunately the PCL can look normal on MRI as early as 6 months after injury but this does not correlate with an improvement in how the knee functions.
The true natural history of untreated PCL tears remains a controversial topic. The general consensus has been that isolated PCL tears do well without surgery and multiple ligament injured knees involving the PCL should be operated on.
Patients with a ruptured PCL who are content with activities that require little in the way of side stepping (running in straight lines, cycling and swimming) may opt for conservative treatment.