What is the LCL and what is the PLC?
The LCL (Lateral Collateral Ligament) is a thin cord-like ligament that runs on the lateral (outer-side) of the knee from the femur to the top of the fibula (thin strut bone that runs parallel to the tibia). The LCL is responsible for stabilising the knee in side -to side movements and against varus loads (where the knee goes outwards but the tibia and foot move inwards towards the midline). Ruptures of the LCL are frequently associated with damage to the Posterolateral Corner (PLC) , and often require surgical reconstruction or repair.
A missed PLC tear may be a reason for a poor outcome after isolated reconstruction of the ACL, as the ACL reconstruction on its own will not correct the rotational instability caused by deficiency of the PLC. PLC injuries also occur frequently in association with PCL injuries. Deficiency of the PLC with significant rotational instability is an indication for surgical reconstruction.