MCL Injury

The knee is the most complex joint in your body and uses a delicately balanced system of bones, ligaments, and other structures to allow you to run, jump, perform cutting movements, and other advanced activities. The knee is made up of three bones: the femur (thigh bone), the tibia (shin bone), and the patella (kneecap). The two joints of the knee are the tibiofemoral joint (between the femur and tibia bones, this is the main knee joint) and the patellofemoral joint (between the kneecap and the trochlea, a groove on the front of the femur). The fibula bone is a thin bone on the outside of your lower leg that does not contribute to the knee joint, but is important to ankle stability. 

Due to the geometry of the knee joint, it is inherently unstable and relies on ligaments, tendons, and other soft tissue (non-bony) structures for stability. 

• Ligaments: The knee ligaments support the knee through range of motion

  • Anterior cruciate ligament: This ligament is the most commonly discussed ligament, as it is commonly injured. It is located in the middle of the knee and runs from the back of the femur to the tibia. The ACL prevents the tibia from moving too far forward.

  • Posterior cruciate ligament: This ligament is also located in the middle of the knee and runs from the front of the femur to the back of the tibia. The PCL prevents the tibia from sliding too far backward.

  • Medial collateral ligament: This ligament is located along the inside of the knee and runs from a bony prominence on the inside of the femur to the inside of the tibia. It prevents the knee from collapsing inward.

  • Lateral collateral ligament: This ligament is located along the outside of the knee and runs from a bony prominence on the outside of the femur to the top of the fibula bone. This ligament works in concert with other soft tissue structures to prevent the knee from collapsing outward.

MCL injuries are very common and occur when the knee sustains a direct blow to the outside of the knee. The MCL can be injured as a partial tear, or a portion of the ligament is torn, or a complete tear. MCL tears can occur in isolation, but are often seen with ACL tears or other injuries.

Types of MCL Injuries

Ligaments are graded based on the amount of injury and looseness that is noted on physical examination. MCL injuries can occur in isolation or in combination with other ligament injuries (multi-ligament knee injuries). There are three types of MCL injuries:

• Grade 1: Mild stretch or partial injury of the MCL, no change in knee stability

• Grade 2: Partial tear of the MCL with a mild change in knee stability

• Grade 3: Complete tear of the MCL leading to an unstable knee.

Symptoms & Diagnosis

Patients with a MCL tear with note swelling of the inside of the knee after the injury with pain and bruising to the inside of the knee. Patients may have difficulty bending the knee as well. Patients with a severe injury may also feel that the knee is unstable with walking. MCL injuries are diagnosed using physical examination and imaging studies to confirm the diagnosis. The physical examination is used to identify areas of pain, swelling, change in range of motion, and laxity (or looseness) of the knee. X-rays are used to look at the bones of the knee. MRI (magnetic resonance imaging) is an important part of the diagnosis and will allow evaluation of all the knee ligaments, meniscus, cartilage, and any other structures that may have been injured.

Treatment

MCL injuries can be treated with non-surgical or surgical means, however, the majority of MCL injuries improve without surgery. Non-surgical treatment options allow patients to return to sports between 2-8 weeks after injury, depending on severity, and include:

• Rest and activity modification: All sports and active pursuits should be stopped until the knee inflammation resolves. Occasionally, patients require several weeks of crutch use to regain a normal gait.

• Non-steroidal anti-inflammatory medications (NSAIDs) can help decrease inflammation

• Brace: Use of a knee brace can help the patient feel more confident and secure when walking

• Physical therapy: This is an important tool to help you strengthen and retrain the muscles of the knee to work better together. Physical therapy is critical to the non-surgical treatment of a PCL injury and involves early quadriceps strengthening exercises and regaining normal knee range of motion

Surgical treatment of MCL injuries is used in patients who have a severe/complete MCL injury or those who have tried a prolonged course of non-surgical treatment and continue to have pain or a sense that the knee is unstable. Patients are able to return to sports at 6-12 months after surgery.

• MCL repair: This procedure uses stitches and anchors to hold the MCL in place to allow it to heal. It can only be performed in certain situations and injury patterns

• MCL reconstruction: This procedure is used in severe injuries to the MCL and uses autograft or allograft tissue to reconstruct the MCL and secure it in place with stitches and metal buttons.