Medial Collateral Ligament (MCL) Injury
What is the Anatomy and Function of the MCL?
The medial collateral ligament (MCL) is one of the four main ligaments that stabilize the knee joint. It is located on the inner side (medial aspect) of the knee and connects the femur (thigh bone) to the tibia (shin bone).
The MCL is composed of superficial and deep fibres, which blend with the joint capsule and medial meniscus.
Its main functions are to:
Provide medial stability, preventing the knee from collapsing inward (valgus movement)
Support rotational control of the knee
Work in coordination with the ACL, PLC, and PCL to maintain joint stability during dynamic motion
The MCL is one of the most commonly injured ligaments in the knee, especially in contact or pivoting sports.
How Does the MCL Tear?
An MCL injury typically occurs when a force pushes the knee inward while the foot is planted — this is called a valgus stress. Common mechanisms include:
A direct blow to the outside of the knee (e.g., in football, rugby, or skiing)
Twisting or pivoting injuries during sports
Depending on the severity, the MCL may sustain a mild sprain (Grade I), a partial tear (Grade II), or a complete tear (Grade III).
What Other Concomitant Injuries Occur with an MCL Tear?
Although isolated MCL tears are common, they may also occur in combination with other knee injuries, including:
Anterior cruciate ligament (ACL) tears and other forms of multiligament knee injuries
Medial meniscus tears
Cartilage injuries and bone bruising
Identifying associated injuries is essential, as they can significantly affect treatment decisions and recovery.
How Do You Diagnose an MCL Tear?
Diagnosis is based on history, clinical examination, and imaging.
History:
A history of a blow to the outer knee or valgus stress.
Localized pain or tenderness on the inner side of the knee.
Physical Examination:
Valgus stress test – performed with the knee at 30° flexion to assess medial laxity.
Tenderness along the course of the MCL
Assessment for stability and other ligament injuries (ACL, PCL).
Imaging:
MRI scan – confirms the grade and location of the tear, and identifies any associated ligament, meniscal, or cartilage damage.
X-rays –exclude associated fractures or avulsions.
What are the Indications for Conservative Management of MCL Tears?
The majority of isolated MCL injuries can be managed non-surgically, with excellent outcomes.
Indications for conservative treatment include:
Grade I (mild sprain) or Grade II (partial tear) injuries
Isolated MCL injury without associated ligament or meniscus damage
Relatively stable knee joint on valgus stress testing
Low- to moderate-demand patients
Conservative management typically involves:
Short-term use of a knee brace for support and stability
Early physiotherapy focusing on quadriceps and hamstring strengthening.
Gradual return to activity over 4–8 weeks, depending on injury severity
Avoidance of valgus stress and twisting during recovery
Most patients return to normal activity within 6–12 weeks with full function.
What are the Indications for Surgical Management of MCL Tears?
Surgical intervention is uncommon but may be required in certain cases.
Indications include:
Grade III (complete) MCL tear with persistent valgus instability
Combined injuries, such as MCL + multi-ligament injuries
Distal avulsion of the MCL from the tibia (“Stener-like lesion”) or femur with tissue retraction or displacement
Failure of non-operative management, with ongoing instability or functional limitation
Surgical repair or reconstruction of the MCL restores the ligament’s anatomy and prevents long-term instability.
MELBOURNE ORTHOPAEDIC SURGERY