The medial collateral ligament (MCL) and the lateral collateral ligament complex (LCL) provide support along the inner and outer sides of the knee and keep the tibia from bending inward (medially) or outward (laterally) relative to the femur.
MCL and LCL injuries frequently occur alongside other knee ligament injuries. The combination of an MCL tear with an ACL Tear and Meniscus Tear is so common it is referred to as the "unhappy triad." Significant valgus or varus forces that injure the collateral ligaments can also damage the PCL, particularly in high-energy trauma.
Medial and Lateral Knee Ligament Injuries
Classification of collateral ligament injuries:
- Grade I: Low grade injury (sprain) with stretching or microtearing of the ligament fibers.
- Grade II: Intermediate grade injury with macroscopic partial tearing and stretching of ligament fibers. Some intact fibers maintain function.
- Grade III: Completely torn/ruptured ligament with lost function.
Diagnosis
A physical exam is performed to assess medial and lateral knee stability with valgus and varus stress testing. When the diagnosis is uncertain or additional injury is suspected, imaging is essential.
A knee MRI is the definitive study for evaluating collateral ligament injuries — it precisely grades the degree of tearing, identifies associated injuries to the ACL, PCL, or meniscus, and detects bone bruising patterns that help confirm the mechanism of injury.
Treatments:
A. Grade I or Grade II Injuries:
- R.I.C.E. (rest, ice, compression, and elevation) in the acute phase of injury.
- Anti-inflammatory drugs (NSAIDs) to help with pain.
- Knee brace to allow healing.
B. Grade III Injury:
- R.I.C.E.
- NSAIDs
- Physical therapy exercises
- Even grade III MCL tears may heal without surgery. In certain circumstances, your surgeon may recommend surgical repair to restore function.
Healing of collateral ligament sprains typically takes from four to six weeks, depending on the severity of injury.
Related Knee Conditions
Get an MRI to Confirm Your Diagnosis
Before surgical planning or starting treatment, a clear MRI diagnosis ensures the right path forward. First Look MRI offers self-pay Knee MRI scans — no doctor's order or insurance required — at our locations in Georgia, Texas, and Colorado.