What is the MCL and what are the types of MCL injury?

The medial collateral ligament is a very strong structure on the inside of the knee.  It has two components the superficial and the deep medial collateral ligaments.  The superficial MCL is the larger component and plays more of a role in knee stability.  The MCL ligament is complex, is active throughout the range of movement and is a very important stabiliser.  It can be injured as part of the injury pattern of ACL injury.  The MCL injury can be divided into three grades:

  • Grade 1 – Grade 1 MCL injury is a sprain with no tearing of the actual ligament.  
  • Grade 2 – This is a partial MCL tear.  
  • Grade 3 – This is a complete tear of the MCL.  The MCL can be completely torn either from its attachment on the femur or mid-substance or at its insertion on the tibia.  

What is the PCL and what are the types of PCL injury?

The posterior cruciate ligament is one of the cruciates in the middle of the knee along with the anterior cruciate ligament.  It is less commonly injured than the ACL.  Its main function is to stop posterior translation or backwards movement of the tibia on the femur.  It is most commonly injured in dashboard injuries and during road traffic accidents when the flexed knees of the passenger hit the dashboard and cause a forceful backward movement of the tibia resulting in a PCL rupture.  It can however be injured in other mechanisms.