Fester Fonvielle

The medial collateral ligament (MCL) is a flat band of connective tissue that runs from the medial epicondyle of the femur to the medial condyle of the tibia and is one of four major ligaments that supports the knee. MCL injuries often occur in sports, being the most common ligamentous injury of the knee, and 60% of skiing knee injuries involve the MCL).

NB The MCL is also known as the  tibial collateral ligament (see image)

The MCL

This structure is divided into superficial and deep ligaments.

2. The Deep medial ligament (dMCL) is divided into two, the meniscofemoral and meniscotibial ligaments.

The medial collateral ligament is recognised as being a primary static stabiliser of the knee and assists in passively stabilising the joint.

The superficial and deep ligaments each have a unique function, making the MCL the primary responder to valgus stress and a secondary restraint to rotational forces.

Together, the MCL also helps guide the knee joint through its full range of motion when a tensile load is applied.

The MCL also prevents hyperextension of the joint and posterior translation of the tibia, secondary to the function of the posterior cruciate ligament (PCL). The posterior oblique ligament, a continuum of oblique fibers at the posterior aspect of the MCL, is responsible for this function.

The ligament also plays a role in joint position sense or proprioceptive feedback. When the MCL is stretched beyond its ability or exposed to an excessive load, it evokes neurological feedback signals that then generate a muscle contraction.

Branches of the superior and inferior genicular arteries supply the MCL. The area near the bony insertions is more richly vascularized.

The MCL is innervated by the medial articular nerve, a branch of the saphenous nerve.

The MCL is one of the most commonly injured ligaments of the knee.

Injuries to the MCL can have detrimental effects to surrounding structures.

Assessment of the MCL is best within 20 to 30 minutes of injury before pain, swelling, and muscle spasms make examination difficult. The assessment includes palpation and a special test, the valgus stress test VST

The anterior aspect of the ligament can be palpated moving vertically, roughly midway along the medial joint line. Focal tenderness indicates an MCL injury.

2. Special test

The VST assesses laxity of the MCL compared to the contralateral knee as a control. An increase in laxity and joint space usually distinguishes damage to the medical collateral ligament.

The patient should be positioned supine.

When assessing for an MCL injury, the examiner should carefully inspect surrounding structures. Suspicion of additional injury may require imaging.

Treatment is often non-operative because the MCL has strong vascular support for healing. See Medial Collateral Ligament Injury.