MCL – Function
The medial collateral ligament (MCL) is one of the major stabilising ligaments of the knee. It is a broad ligament found on the inside of the knee, and its primary function is to resist force that is applied to the outside of the knee. It has attachment to the femur (thigh bone) and to the tibia (shin bone).
An MCL tear is typically sustained during a collision or forceful contact on the outside of the knee. This results in an injury of various severity to the MCL. The pain is felt immediately on the inner side of the knee. The MCL can be injured in isolation, or can be injured in combination with other internal knee structures, such as the ACL.
MCL Tear – Symptoms
Patients who sustain a MCL tear, will experience acute pain on the medial (inside) of the knee joint. Associated swelling and the feeling that the knee is going to buckle (‘Instability’) are also common. The severity of symptoms correlates with the severity of the injury.
MCL Tear – Making the Diagnosis
In an isolated MCL injury, with a classic mechanism of injury, it can be possible to make the diagnosis on physical examination alone. The MCL’s integrity is assessed by performing a ‘Valgus stress test’ (See image). It is important to undergo a thorough assessment, as there are specific situations where further evaluation with an MRI and orthopaedic surgeon review is warranted.
MCL Tear – Management
The majority of isolated MCL tears can be managed conservatively with a range of motion knee brace. The brace restricts excessive sideways movement of the knee joint and allows the MCL to heal.
There are three main scenarios where surgical intervention may be warranted.
MCL may have ‘flipped’ superficial to the hamstring tendons. Preventing MCL healing to bone.
Patient experiences ongoing instability following an acute injury
When the MCL is injured in combination with other internal knee ligaments (i.e ACL/PCL). This represents a complex knee injury.