The Medial Collateral Ligament (MCL) is on the inner (big toe) side of the knee and stops the knee joint from opening up on that side. This is a very common injury in field sports, and other jumping sports. The good news is that most MCL injuries heal up without the need for surgery. Treatment involves using a hinged knee brace for about 2 months and then a gradual return to sports. Even in patients who sustain a combined ACL and MCL injury, often the MCL just needs knee bracing for 2 months, and only the ACL reconstruction surgery needs to be performed.
The Lateral Collateral Ligament (LCL) is on the outer (little toe) side of the knee. It is also often grouped together with the Posterolateral Corner (PLC) of the knee. The LCL and PLC are rarely injured in sports injuries. Often to tear these ligaments a higher velocity and force is required, such as in road traffic accidents, though trampoline accidents can cause these injuries as well. Many times, LCL and PLC injuries are associated with injuries to the ACL or PCL. Very often, LCL and PLC injuries require complex reconstruction knee ligament surgery.
The Posterior Cruciate Ligament (PCL) is next to the ACL in the knee, and stops the tibia (shin bone) from sliding backwards from the thigh bone (femur). It is most often injured in a fall with a direct impact to the front of the knee such as in field sports, falling from a bicycle, or motor accidents. Most mild to moderate (Grade 1 and Grade 2) PCL injuries recover without surgery can patients can return to sports within 2-3 months. Only the most severe PCL (Grade 3) injuries need surgery, or when the PCL tear is combined with other ligament injuries to the ACL, LCL or PLC.