Description of an LCL Injury (FCL Injury)
The lateral collateral ligament (LCL), also called the fibular collateral ligament (FCL), is the main structure on the lateral, or outside, portion of the knee to prevent the knee from gapping open. The term fibular collateral ligament (FCL) is more anatomically correct, but this ligament is more commonly referred to as lateral collateral ligament (LCL). In clinical terms, this is noted as varus gapping. It is a thin, round, stout ligament, which courses from the femur down to the lateral aspect of the fibular head.
An LCL injury can occur with sudden stops and starts, a blow to the inside of their knee, or a contact or noncontact hyperextension injury. Sometimes a LCL tear of the knee can go undiagnosed for a few weeks before an athlete notices problems with instability.