Medial Collateral Ligament (MCL) Injury

What are the different types of medial collateral ligament (MCL) injuries?

An injury to a ligament is called a sprain. Like any other sprain, MCL injuries are graded by their severity. When the fibers of the ligament are stretched but not torn, this is referred to as a Grade 1 sprain. Grade 2 sprains are when the ligament fibers are partially torn. When the ligament is completely torn or disrupted, this is a grade 3 sprain.

Because of the anatomy and how the MCL is related to the medial meniscus (cartilage) and the ACL (anterior cruciate ligament), these two structures may also be damaged in association with an MCL injury.

What are causes and risk factors of medial collateral ligament (MCL) injuries?

MCL injuries are the most common ligament sprain of the knee. They are often sports-related and can occur in any age group. Contact sports are the most common risks, including football, hockey, wrestling, and martial arts. Males tend to be more at risk than females.

MCL injuries occur usually from a sudden impact to the outer part of knee. The injury may be either due to contact, being hit on the outside part of the knee, or non contact due to twisting, cutting, or stopping suddenly (deceleration).

What are medial collateral ligament (MCL) injury symptoms and signs?

Pain is the first symptom of an MCL injury. It typically occurs almost immediately and is located along the course of the ligament. Sometimes this is associated with swelling within the knee joint. Occasionally, swelling develops in a matter of minutes. The Pain of an MCL sprain will also cause the person to limp in order to protect the knee joint.

What tests are used to diagnose and assess medial collateral ligament (MCL) injuries?

The diagnosis of an MCL sprain is usually made by history and physical examination. The patient often knows the mechanism of injury, that is precisely what they were doing and what position their body was in when the injury occurred. 

This helps the health-care professional understand the stresses that were put on the knee joint. Other questions might include whether the patient was able to walk, whether the knee began to swell, and how long it took for that to happen after the injury.

The physical examination includes looking at the knee to see whether or not it is swollen and touching the knee in various places to find places of tenderness and pain. With MCL sprains, there is tenderness along the course of the ligament on the inner aspect of the knee.

The ligament can also be stressed on physical examination. By pushing on the outer side of the knee, the examiner can determine if the MCL is stable or unstable. This can be a rough assessment of the grade of sprain, where a grade 1 sprain is stable and a grade 3 sprain is unstable.

Physical examination concentrates on the knee joint and the hip and ankle to identify any other associated injuries.

Plain X-rays of the knee can be used to identify fractures of the femur and tibia bones. An MRI is the best way to actually visualize the MCL and determine the grade of sprain, but it is not always necessary. If there is concern that there is also a tear of the medial meniscus or anterior cruciate ligament, an MRI may be appropriate.