Diagnostic Radiology/Musculoskeletal Imaging/Trauma/Medial Collateral Ligament Injury

Anatomy

The medial collateral ligament is typically divided into the superficial and deep bands. The superficial portion of the ligament typically arises from the medial femoral condyle and passes distally to insert approx. 5 cm below the joint line and posterior to the pes anserinus on the medial aspect of the proximal tibia. Superficial fibers are separated from the deep fibers by a bursa.

The deep ligament is firmly attached to the capsule and the midportion of the medial meniscus and attaches to the femur and tibia adjacent to the joint. The medial collateral ligament is a stabilizer that resists external rotation and anterior forces and is more often injured than its lateral counterpart.

Click here for anatomy link for Medial Collateral Ligament anatomy from Wheeless' Textbook of Orthopaedics.

Pathophysiology

This injury usually occurs when a blow to the outer side of the knee causes stretching or tearing of the medial collateral ligament. It can also be caused by twisting the knee. Specifically, the ligament is injured due to a valgus stress with the knee in flexion.

Grading Injury

TYPES OF MEDIAL COLLATERAL LIGAMENT INJURY(GRADE I-III):

Three appearances of the MCL with T2 Weighted Images.

I. A sprain, shows high T2 signal in the soft tissues medial to the MCL.

II. A severe sprain or partial tear, shows high signal in the soft tissues medial to the MCL, but also has high signal or partial disruption of the MCL itself. As well, there can be thinning of the MCl itself.

III. A complete tear, shows complete disruption of the MCL.

Associated Injuries

Associated injuries of the capsule specifically meniscocapsular separation, and can be diagnosed by noting fluid between the MCL and the medial meniscus. Additionally, injuries of the anterior cruciate ligament are also commonly seen with these injuries.

Commonly seen injury is so named the UNHAPPY TRIAD:

ANTERIOR CRUCIATE LIGAMENT TEAR
MEDIAL COLLATERAL LIGAMENT INJURY
MEDIAL MENISCUS TEAR

Treatment

Treatment of a medial collateral ligament injury rarely requires surgical intervention. Grade I sprains of the MCL usually resolve within a few weeks. Resting from activity, icing the injury and the use of anti-inflammatories will usually be all the treatment that is needed.

When a grade II MCL sprain occurs, use of a hinged knee brace is common in early treatment. Athletes with a grade II injury can return to activity once they are not having pain over the MCL. When a grade III injury occurs, patients usually wear a hinged knee brace and protect weight-bearing with a gradual return to normal activities. Patients with more severe injuries usually require physical therapy and will not return to their full level of activity for 3 to 4 months.

References

Medial Collateral Ligament Injury by Juan Millan, M.D., University of Washington Department of Radiology
Agranoff AB, Kaplan RJ. Medial Collateral and Lateral Collateral Ligament Injury. EMedicine online.
Medial Collateral Ligament. Wheeless' Textbook of Orthopaedics online.