Your knee is a complex system of ligaments, tendons, bones, and cartilage that make up the largest joint in the body.
The medial collateral ligament (MCL) keeps your knee from bending inward. But it is susceptible to injury, especially during activities that involve bending, twisting, or a quick change of direction.
Read on to learn more about MCL injuries and treatment.
What Is an MCL?
The MCL — found on the inside of the knee — connects the femur (thighbone) to the tibia (shinbone). Its job is to stabilize side-to-side movements.
“The MCL’s function is to prevent what we call valgus stress,” says Volker Musahl, MD, chief, Division of Sports Medicine, UPMC. “That can happen when the tibia bone moves away from your body and the femur bone moves toward your body.”
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What Causes MCL Injuries?
An MCL injury is the most common type of knee ligament injury. It occurs when force is applied to the outside of the knee and moves it sideways.
MCL injuries are most common in sports — including football, soccer, skiing, and hockey — when direct force to the outside of the knee pushes it inward. They also can occur when your knee twists violently inward while it’s bent.
“Let’s say you’re playing football and someone runs into the outside of your knee with their helmet,” says Dr. Musahl. “The inside of the knee may experience stress and the MCL can tear.”
Types of MCL Injuries
MCL injuries —classified as sprains — have different levels of severity.
- Grade I sprains occur when the MCL is stretched but not torn. It still provides stability to the knee.
- Grade II sprains occur when there is a partial tear of the ligament. The MCL is loose and some instability is possible.
- Grade III sprains occur when there is a complete tear of the MCL. When you have a complete tear, the knee joint is unstable.
Symptoms and Diagnosis of MCL Injuries
The severity of symptoms people experience from an MCL injury can vary depending on its grade. Common symptoms include:
- A “popping” sound or sensation in the knee at the time of the injury
- Pain on the inside of your knee
- Unstable feeling in the knee
- Noticeable looseness when you walk
To diagnose an MCL injury, the doctor will ask how the injury occurred and assess your symptoms. A physical examination will help the doctor determine the stability of the ligaments. Imaging tests, such as x-rays and magnetic resonance imaging (MRI) scans, can help with the diagnosis.
MCL Treatment and Recovery
Treatment depends on the severity of the MCL injury.
Most MCL injuries don’t require surgery. The doctor will likely recommend nonsurgical treatment including:
- The R.I.C.E. method (rest, ice, compression, elevation)
- Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, for pain
- Wearing a knee brace for a short time
- Using crutches
A severe MCL tear may need a surgical fix. Doctors can reattach the torn ligament or reconstruct it using tissue grafted from elsewhere in the body.
Recovery time from an MCL injury depends on the severity of the injury. Recovery from a grade 1 sprain can take a few weeks, while severe tears can take three or four months.
Recovery often involves physical therapy to regain strength and flexibility in the injured knee.
MCL Injury Prevention
MCL injuries can’t be fully prevented. Wearing a knee brace may help provide stability and lower the risk of an MCL injury. For competitive athletes, there is a risk of re-injuring the ligament or injuring the other knee.
One risk factor for an MCL injury involves the way you move and jump — the balance between your knees and other body parts like your feet and ankles. Working with a sports performance trainer can help correct imbalances that may increase your risk for injury.
MCL Care at UPMC
UPMC Sports Medicine provides world-class care for a wide variety of athletic injuries. At the Freddie Fu Sports Medicine Center, you’ll find experts in a range of specialties — including surgeons, primary care sports medicine doctors, athletic trainers, physical therapists, and more — all under one roof.
“Everything is here, so it’s a pretty phenomenal place,” says Dr. Musahl. “Everyone here loves what they do and it shows in every aspect of patient care.”
To contact UPMC Sports Medicine, call 1-855-937-7678 or visit us online.
Editor's Note: This article was originally published on , and was last reviewed on .
About Sports Medicine
An athletic lifestyle carries the potential for injury. Whether you’re an elite athlete or a weekend warrior, UPMC Sports Medicine can help. If you are looking to prevent, treat, or rehabilitate a sports injury, our multidisciplinary team of experts can help you get back into the game. If you are seeking to improve your athletic performance, we can work with you to meet your goals. We serve athletes and active people of all ages and experience levels. Our goal is to help you keep doing what you love. Visit our website to find a specialist near you.