MCL INJURY

Medial Collateral Ligament (MCL) Injury: A Comprehensive Overview

Definition:

  • An MCL injury refers to damage to the medial collateral ligament, a key stabilizing structure on the inner side of the knee. This ligament connects the femur (thigh bone) to the tibia (shin bone) and prevents excessive inward movement (valgus stress) of the knee joint. 

  • Injuries can range from mild sprains to complete tears, with varying degrees of severity and functional impairment. 

Cause:

  • Direct Impact: A blow to the outer side of the knee, commonly seen in contact sports like football and hockey.

  • Non-Contact Mechanisms: Twisting motions or sudden changes in direction, especially when the foot is planted. 

  • Valgus Stress: Excessive inward bending of the knee, often combined with external rotation forces. 

  • Anatomical Factors: Pre-existing knee alignment issues or muscle imbalances may predispose individuals to MCL injuries.

Classification:

  • Grade I (Mild): Stretching of the ligament without significant tearing; mild pain and swelling.

  • Grade II (Moderate): Partial tear with moderate pain, swelling, and some instability. 

  • Grade III (Severe): Complete rupture of the ligament leading to significant instability and functional impairment. 

  • Anatomical Variants: Involvement of superficial (sMCL) and deep (dMCL) fibers, with potential for combined injuries affecting other structures like the posterior oblique ligament (POL).

Signs and Symptoms:

  • Pain: Localized on the inner side of the knee, often exacerbated by valgus stress or twisting motions.

  • Swelling: May develop within hours post-injury, indicating inflammation. 

  • Instability: A feeling of the knee "giving way," especially during weight-bearing activities. 

  • Bruising: Discoloration on the inner knee surface due to blood vessel rupture. 

  • Limited Range of Motion: Difficulty fully extending or flexing the knee.

  • Positive Physical Tests: Lachman test and valgus stress test may elicit pain or increased joint laxity.

Conclusion:

MCL injuries are prevalent, particularly among athletes involved in contact and pivoting sports. Understanding the etiology, classification, and clinical presentation is crucial for effective management and rehabilitation. Most MCL injuries can be managed conservatively, with surgical intervention reserved for severe cases or when associated with other ligamentous injuries.