MCL Tear Flashcards
What is the most common ligament injured in the knee?
The medial collateral ligament (MCL) is the most commonly injured ligament of the knee.
What is the function of the MCL?
The MCL primary function is to act as a valgus stabiliser of the knee and is most often injured when external rotational forces are applied to the lateral knee, such as a impact to the outside of the knee.
Differentiate between Grades I-III of MCL tear
MCL injuries can be graded from one to three:
- Grade I: mild injury, with minimally torn fibres and no loss of MCL integrity
- Grade II: moderate injury, with an incomplete tear and increased laxity of the MCL
- Grade III: severe injury, with a complete tear and gross laxity of the MCL
What are the clinical features of an MCL tear?
A medial collateral ligament tear will typically occurs after trauma to the lateral aspect of the knee.
In isolated medial collateral ligament tears, this is usually a direct blow in a valgus stress direction. Non-contact MCL injuries occur less commonly, and often arise from a valgus stress with external rotation force, such as in skiing.
The patient may report hearing a ‘pop’ with immediate medial joint line pain. Swelling tends to follow after a few hours (unless there is an associated haemarthrosis, in which case it will occur within minutes).
The main clinical finding on examination will be increased laxity when testing the MCL, via the valgus stress test. The patient will be extremely tender along the medial joint line, but may be able to weight bear.
What investigations should be ordered for an MCL tear?
Any patient following trauma with significant knee pain and swelling should have a plain film radiograph to exclude any fracture.
The gold-standard investigation to confirm the diagnosis for an MCL tear is via MRI scanning, delineating the exact extent and grade of the tear.
Briefly describe the treatment for Grade I MCL tear
Grade I Injury: Rest, Ice, Compression, and Elevation (RICE) with analgesia (typically NSAIDs) as the mainstay. Strength training as tolerated should be incorporated, with an aim to return to full exercise within around 6 weeks.
Briefly describe the treatment for Grade II MCL tear
Grade II Injury: Analgesia with a knee brace and weight-bearing/strength training as tolerated. Patients should aim to be able to return to full exercise within around 10 weeks.
Briefly describe the treatment for Grade III MCL tear
Grade III Injury: Analgesia with a knee brace and crutches, however any associated distal avulsion then surgery is considered. Patients should aim to be able to return to full exercise within around 12 weeks.
What are the complications of a MCL tear?
The main complications following a MCL tear are instability in the joint and damage to the saphenous nerve.
What differentials should be considered for MCL tear?
In the acutely swollen knee following trauma, the main differentials to consider include fractures, meniscal injury and multi-ligament tears (particularly MCL & ACL).
How can Grade II and III tears be differentiated?
A Grade II and III tear can be distinguished clinically on medial stress testing;
- Grade II is lax in 30 degrees of knee flexion but solid in full extension
- Grade III is lax in both these positions
