The medial collateral ligament (MCL) connects the bones in the thigh and lower leg. The MCL runs along the inside of the knee, while the lateral collateral ligament (LCL) runs along the outside of the knee. Together, these two ligaments, along with others, help to keep the knee in place.
Ligaments consist of strong connective tissue. A sprain stretches the ligament, which can become loose after a severe injury. A tear is a more severe injury that splits the ligament in two. When someone tears the MCL, it may not hold the knee in place as securely.
MCL injuries often happen during contact sports. Direct contact to the outside of the knee during a collision can push the knee sideways. This puts a lot of pressure on the MCL, which can tear. Contracting the muscle while running and turning can also put enough stress on the ligament to sprain or tear it.
An MCL tear causes pain on the inside of the knee. Tearing the MCL is likely to cause more severe pain that spraining the ligament. A person may notice a popping sound at the time of the injury. This is the sound of the MCL tearing.
A person is likely to notice swelling in the area, which may not happen immediately. Swelling can spread to other areas of the knee joint in the days following the injury.
The knee may feel stiff, and a person may have difficulty straightening their leg or bending their knee. They may also find climbing the stairs or sitting in a chair challenging as this requires them to bend their knee.
A torn MCL can affect the stability of the knee. A person may feel as if their knee might give way or that their kneecap feels loose.
It is possible to damage other ligaments at the same time as the MCL. If a blow to the knee is severe, it could cause damage to:
- the LCL on the outside of the knee
- the anterior cruciate ligament (ACL), which connects bones in the thigh and lower leg at the front of the knee
This causes pain in these parts of the knee. It can take longer for an injury to heal if a person damages multiple ligaments.
A doctor will usually ask about the activity that led to the injury; for example, a collision with another player during a contact sport. They are likely to ask about any symptoms.
A doctor should be able to diagnose an MCL tear after a physical examination of the knee. A doctor may compare one knee with the other, look closely at the injured knee, and gently feel for any swelling and the location of the tenderness.
A doctor might carry out further imaging tests to confirm the diagnosis. An MRI scan gives a picture of soft tissues in the body and can show a tear in the MCL. An X-ray can provide more information if a doctor suspects a broken bone in or around the knee.
Putting ice on the injury will help to reduce swelling and relieve pain. Hold some crushed ice against the side of the injured knee for 15 to 20 minutes and repeat as necessary, leaving a 1-hour interval between treatments. Raising the knee on a chair or stool can help to ease discomfort.
Protect the MCL while it is healing to prevent further injury and speed up recovery time. A knee brace can help to prevent any sideways movement of the knee joint and protect the MCL from strain and pressure.
If an MCL tear is severe, a doctor may recommend that a person use crutches to avoid putting weight on the knee joint.
Resting the knee after an MCL tear can help speed up healing. People should avoid contact sports and movement that puts too much strain on the MCL until the injury heals fully. This can help to prevent further damage.
In some cases, surgery may be necessary. If the location of an MCL tear means that it is unlikely to heal, or if a person has torn more than one ligament, a doctor may recommend surgery. Surgery involves reconnecting the ends of the ligament or reattaching it to the bone if necessary.
Physical therapy can help a person regain normal movement in the knee. Doing gentle exercises recommended by a physical therapist can also help to strengthen the muscles around the knee, which will support healing.
A physical therapist will be able to advise on strengthening exercises to aid recovery after an MCL tear. Some possible exercises may include:
1. Hamstring curl
- Stand up straight, engaging the stomach muscles.
- Stand on one leg and slowly bend the opposite knee by bringing the heel up toward the buttocks.
- Hold for 30 seconds before repeating on the other side of the body.
- A person can hold on to a chair or table for support if needed.
2. Wall slide
- Standing up straight, with both feet flat on the ground, place the back firmly against a wall.
- Slowly slide down, keeping the back against the wall until reaching a squatting position.
- Hold for 30 seconds.
- Push up from the feet to stand up, keeping the back flat against the wall.
- Repeat 10 to 15 times.
3. Chair squat
- Standing on one leg, slowly squat toward sitting down onto a chair.
- Return to a standing position, again standing on one leg.
- Bend at the waist and keep the body in a straight line when standing.
- A person may need to build up to sitting fully on the chair