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Knee Ligament Injury

MCL Injury

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Posted 1 year ago


Last updated: 20/11/2023


by James McCormack

James McCormack
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Ligaments are fibrous connective tissue that attach bones to bones and limit the movement at that joint in a particular direction. The MCL of the knee is the medial collateral ligament, attaching the femur and tibia on the inside of the knee. The MCL is made up of a superficial band and a deep band, both generally speaking are attached to the femur and the tibia.

The superficial MCL is attached superiorly to the medial femoral condyle and inferiorly has two insertion points, one into the semimembranosus tendon (one of the hamstrings) and the second into the upper medial surface of the tibia.

The deep MCL is also divided into two: the meniscofemoral and meniscotibial ligaments. The meniscofemoral part attaches from the femur near the superficial MCL attachment and to the medial meniscus, and the meniscotibial is attached to the medial meniscus and the medial tibial plateaux.

Diagram of medial collateral ligament injury

The Function of the MCL Explained

The primary function of the MCL  is to restrict the inward movement of the knee, known as a valgus movement. It also helps the smooth movement of the knee when a tension force is applied.

The superficial MCL also helps stabilise external rotation at 30º of knee flexion, and the deep MCL helps stabilise medial rotation when the knee is 0-90º flexed.

There is also some assistance of the MCL in preventing hyperextension of the knee and the backward movement of the tibia on the femur.

An additional function of the MCL is feedback about the joint position to the brain, known as proprioception.

photo of ski injury


An MCL injury is when the ligament is stretched to its capacity. The fibrous connective tissue is damaged as a result. The most common mechanism of injury is an excessive inward force of the knee. This is commonly the cause of MCL injuries that occur while skiing or with a tackle in rugby, football, or soccer.

Twisting the knee or hyperextension are other frequent mechanisms of MCL injury seen in sports. Other sports with a high incidence of MCL injury include jiu-jitsu and wrestling.

Not all injuries occur through sport. A fall or direct blow to the area can cause damage to the ligament. And some people are more at risk than others.

If your knee moves inwards when walking, or if you are overweight, there will be more stress on the MCL, which can cause a chronic injury.

During pregnancy, hormones are released that make all ligaments more lax or stretchy, so during pregnancy, ligament injuries are more common.


It is essential to take a thorough history to hear the symptoms, lifestyle and activity levels of the individual, and if there was a specific mechanism of injury.

The knee examination should include a general assessment of the person’s movements, strength and mobility and more specific orthopaedic tests. A valgus stress test is the best MCL injury test that can be used.

It should assess the laxity and pain provocation of passively moving the knee into a valgus position with the knee at 0º and 30º of flexion. The measure of excess movement coupled with pain can help to determine the classification and severity of the injury.

Other tests should be performed to rule in or out of other possible diagnoses. Differential diagnoses include medial meniscus injury, Pes Anserine Bursitis and osteoarthritis.


Grade 1 – Symptoms of low pain, without swelling or joint instability. Minimal damage with less than 10% of ligament fibres torn. Assessment will find pain on palpation of the ligament with 0-3mm of excess joint movement.

Grade 2 – Symptoms of moderate to high pain, with swelling and very mild, if any, joint instability. Moderate damage with more than 10% of ligament fibres torn. Assessment will find pain on palpation and swelling, and there is 5-10mm of excess joint movement with pain.

Grade 3 – Symptoms of high pain, with swelling and joint instability. Severe damage with complete or near complete rupture of the ligament. Assessment will find pain on palpation, swelling, and >10mm of excess movement of the joint or no end feel to ligament stress tests.


The signs and symptoms of an MCL injury will vary depending on the severity, mechanism of injury and if any other structures were injured at the same time. The most common symptom is pain location on the inside of the knee; this may be more intense pain when bending the knee.

It might feel like an ache with a minor injury, more intense, sharp, or burning with more severe injuries. If there is a moderate to severe injury to the ligament, there may be bruising and swelling around the inside of the knee. But in many cases, there can be no swelling.

MCL injuries can present with symptoms that include instability or the knee giving out, clicking or popping sensations, or feeling unable to bend or straighten the knee due to pain. The joint pain can be worse at night, and many people find it difficult to find a good sleeping position that is comfortable.


In addition to clinical assessment, imaging with MRI,  ultrasound and X-ray can be helpful to rule in the diagnosis of an MCL injury and rule out other conditions.

Sensitive imaging, such as MRI or ultrasound, can also help classify the injury.

Picture of MRI Machine

Treatment of Grade 1 MCL Tears

An initial period of home treatment involves rest and ice, and if there is swelling, compression and elevation, for several days to a week. No sport and minimal walking should be performed during this time. Exercises for joint mobility, muscle flexibility and activation of the quadriceps are helpful during this period. If pain is high, crutches might be helpful for mobilising but are not often needed for this level of injury.

Further rehabilitation should follow this period of rest. A biomechanical assessment is helpful once the pain has subsided to see movement quality and address tight or weak areas that may have contributed to the injury or impact recovery. In addition, building strength in the leg muscles around the knee joint will help support the knee.

Recovery from a grade 1 MCL injury is between 1-4 weeks. 

Photo of lady in treatment for MCL injury wearing brace and using crutches

Treatment for Grade 2 & 3 MCL Tears

The initial rest period of 2-4 weeks should include the use of a brace, and in most cases for grade 2 and with all cases of grade 3 tears, crutches will be used to reduce weight bearing and manage pain. Ice can be used for pain relief and medication if needed, and compression and elevation are strongly recommended as there will be swelling.

Rehabilitation should be guided by a medical professional such as a physical therapist. A brace should support medial and lateral movements, and hinged braces can be fixed to restrict the range of movement. Straightening the knee fully past 20º of flexion and bending the knee over 90-100º will put the MCL under more strain and can delay healing.

Rehab protocols include early activation exercises for the quadriceps muscles to facilitate faster recovery, and other exercises will be prescribed to you depending on your needs. You can read more about exercises in our article, MCL Injury Exercises.

How long does it take an MCL injury to heal?

Typically, ligaments, including the MCL, take 6 weeks to recover. In severe cases, this can take longer.

How do you sleep with a torn MCL?

It is expected to have difficulty finding a comfortable sleeping position with an MCL injury. Either pressure on the inside of your knee or your knee being entirely straight can be painful. Here are some tips to help you get comfortable and get a good night’s sleep.

Sleeping on your side: place a pillow between your knees to keep your knees hip-width apart and provide some cushioning from the pressure of your knees together.

Sleeping on your front: place a pillow under your ankles to keep your knees slightly bent and lessen the pressure on the front of your knee.

Sleeping on your back: place a pillow under your knees to keep your knees slightly bent and supported.

Is Cycling Good for MCL Injury Rehab?

Cycling, or using an exercise bike, is an excellent form of exercise when recovering from an MCL injury. The positions that stretch and stress the MCL most are avoided: full extension and flexion, rotation, and inward movement of the knee. 

Make sure you have a good set-up on the bike so you do not overextend your leg. Check if your saddle is too high or bending your knee too much if your saddle is too low. As you rotate the peddles, check that your knees move in a straight line and do not move inwards towards the top tube.

Physiotherapy with James McCormack

This article is written by James McCormack, a Lower Limb Specialist who is an expert in treating Knee injuries.

This is not medical advice. We recommend a consultation with a medical professional such as James McCormack if you are experiencing any of the symptoms discussed in this article. James offers Online Physiotherapy Appointments weekly and face-to-face appointments in his London clinic.

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