The next instalment on our topic of knee anatomy and injuries is the MCL, or Medial Collateral Ligament. The MCL doesn’t get quite as much air-time as the Meniscus and the ACL but is actually a commonly injured ligament. It is often injured in the corresponding meniscus or ACL injury, it just doesn’t have the same sort of profile as the others when it comes to the media hype!

For those of you who have experienced an MCL injury, you will know just how sensitive these can be, and, if not managed appropriately, the extent of dysfunction they can cause, often keeping people off the sporting field for multiple weeks – even for a small grade injury.

So, where is it and what does it do?

You might now have an understanding that Medial refers to the inside of the knee. So the Medial Collateral Ligament runs from top to bottom across the inside of your knee. It is quite a large ligament and needs to be robust to tolerate the sort of pressure the knee can be exposed to. Take a look at the diagram here and you should also be able to palpate your own MCL by running your finger across the inside of your knee joint.


The MCL plays a primary role in limiting how far your knee can move in a side to side┬ádirection. The MCL is exposed when pressure comes from the outside – in, such as a tackle from the outside of the knee or, similarly to the ACL, when there is significant dynamic load such as a side step. As mentioned before, the MCL will often be injured at the same time as the ACL, so there are similarities in the mechanism of injury. The difference being, if there isn’t as much rotation, the ACL may be unharmed.


We describe ligament injuries in terms of Grades of Tear. Take a look at the diagram here. More commonly in the community, a Grade 1 or 2 Tear may be known as a “Sprain” or “Strain” and a Grade 3 Tear may be known as a “Complete Rupture”.


How Do You Assess an MCL Injury?

If you have read my previous post on ACL Injury (see here – ) I spoke about the ability to diagnose an injury based on the way it occurred and the story of the patient, before even seeing the knee itself. The MCL is the same. There is often a characteristic incident where someone describes force being applied that loads up the inside of the knee. There is often pain associated right over the MCL and there is also often pain to walk and put pressure or load on the injured ligament.

Another characteristic is pain to touch when prodding around the injured ligament. Due to anatomy, the ligament is best tested when the knee is bent at 30 degrees. We apply pressure from the outside of the knee to stress the MCL on the inside. We will look for either looseness in the ligament that is different to the other knee, or soreness, or both.


To Operate or Not to Operate?

The good news is that MCL injuries in isolation very rarely need surgery, even for Grade 3 Tears. There are certainly some cases where it will be necessary, but these are not as common as surgeries for the Meniscus and ACL.

If there is a Full Grade 3 Tear, typically a Hinged Brace will be worn to protect the ligament whilst it heals. Often, without surgical repair, the ligament will still heal to provide adequate stability again.


In most Grade 1 and Grade 2 injuries, some supportive strapping is often adequate to reduce pressure on the ligament and reduce pain. Everyone’s injury is a little different, but typically with a low grade tear, within 4 – 6 weeks, most people are back to a good level of activity.


Of course, different progressions of taping, Physio treatment and rehabilitation exercises will be applied for each individual and this will be determined between yourself and your treating clinician ­čÖé

If you have any questions, email me