The lateral collateral ligament (LCL) may be injured or torn during contact sports, such as football and hockey, or sports that involve quickly turning or changing direction, such as soccer and basketball. LCL injuries are commonly reported after the following instances:
- Direct blow to the inside of the knee, such as during a football tackle
- Quickly changing directions or pivoting on one foot, such as in soccer or basketball
- Landing awkwardly from a jump, such as during volleyball or basketball
People may also note instability in their knee, particularly with side-to-side or pivoting activities.
Isolated LCL tears are less common than other ligament injuries, such as medial collateral ligament (MCL) or anterior cruciate ligament (ACL) tears. They are most often seen in athletes and alongside other injuries, such as knee dislocations.
What Is the Lateral Collateral Ligament?
The LCL is one of the 4 main stabilizing ligaments of the knee. Ligaments are strong fibrous bands that connect bone to other bone. The LCL is located on the outside of the knee and connects the femur (thighbone) to the fibula (a slim bone that runs down the outside of the calf and forms part of the ankle joint).
While the LCL is located on the outside of the knee, the medial collateral ligament (MCL) is located on the inside. Together, the LCL and MCL limit the knee’s side-to-side movement.
The other two main ligaments, the anterior cruciate ligament (ACL) and posterior collateral ligament (PCL), limit the tibia’s (shin bone) and femur’s back-and-fourth movement.
The LCL Injury Grading System
An LCL injury may be diagnosed when the ligament is overstretched or torn. Ligament injures are referred to as sprains or tears. A doctor may refer to an LCL injury by its grade, which is based on severity:
- Grade I tears refer to a slightly or mildly overstretched LCL and does not usually affect knee stability.
- Grade II tears refer to a ligament that has been severely stretched or partially torn and may cause some joint instability.
- Grade III tears refer to a complete tear of the LCL. A completely torn LCL may make it difficult to put weight on the affected knee.
Generally, the grade of the tear will affect symptoms.