Medial Collateral Ligament (MCL) Injuries
The medial collateral ligament (MCL) is a broad ligament which sits on the inner aspect of the knee, connecting the femur to the tibia.
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The role of the MCL is to help stabilise the bones of the knee joint. It prevents excessive movement of the tibia moving outwards relative to the femur (valgus direction).
MCL injury is the commonest of the knee ligament injuries. It may occur in isolation, or in combination with ACL rupture, meniscal tears, complex ligament injury, or fracture.
MCL tears occur with a wrenching or twisting injury- eg. a “valgus” contact injury. It is painful when it happens. A tearing sensation may be felt. Swelling and pain is only felt on the inner aspect of the knee. If the whole knee swells up rapidly, it is probably more than just an MCL injury.
Examination will usually show tenderness on the inner aspect of the knee at the point where the MCL is torn. It can tear in the middle, or it can pull off the bone at either end.
Early accurate diagnosis is important to enable optimum treatment outcome.
MCL tears are graded into three groups.
Grade 1- partial tear or sprain, when some fibres are torn but it is not really stretched. Examination will reveal pain and tenderness, but no laxity.
Grade 2- partial tear with definite stretching, and will feel lax when examined.
Grade 3- a complete rupture with dramatic opening up. This is more likely to have an associated ACL tear.
Grade 2 and 3 are distinguished by special examinations.
X-rays might be normal, unless a fragment of bone is pulled off. Sometimes an excessive gap between the bones on the inner aspect will be apparent.
A Pellegrini-stieda lesion is seen as calcification at the top of the ligament in some chronic cases.
MRI scans will show up MCL tears, as will ultrasound scans, but they are not always necessary.
An isolated MCL tear will heal very well without the need for surgery.
Grade 1 injuries are treated according to symptoms. No brace is required. Crutches can be used early on until it is comfortable enough to walk without them. Rest, ice, compression, elevation and physiotherapy are all beneficial. Full recovery is at least six weeks.
Grade 2 and grade 3 injuries are usually treated with a brace for six weeks, to prevent the MCL stretching up while it is trying to heal. Although it is possible to do well without bracing, most surgeons feel it is beneficial to the outcome. For that reason early accurate diagnosis is important, to avoid missing the boat with bracing treatment. It can take up to 3 months for full recovery.
Surgery is rarely required. Repair might be considered urgently where there is a complex ligament injury eg. knee dislocation.
In chronic laxity, especially with other ligament tears, reconstruction with the patient’s own hamstring tendon, or artificial graft material, is occasionally undertaken.
In summary, most patients with MCL tears do very well without surgery, with no long-term issues.