The lateral collateral ligament of the knee is a cord-like structure connecting the lateral femoral epicondyle to the fibular head, the primary component of the posterolateral corner complex that resists varus forces and external tibial rotation. Unlike the MCL, the LCL has no attachment to the lateral meniscus, which explains why isolated lateral meniscus tears rarely accompany LCL injuries. The common peroneal nerve courses immediately posterior to the LCL fibular insertion.
| Origin | Lateral femoral epicondyle |
|---|---|
| Insertion | Head of the fibula |
| Actions | Primary restraint against varus stress at the knee; part of the posterolateral corner complex |
|---|
LCL injuries are less common than MCL injuries but more complex because they are rarely isolated — LCL disruption typically accompanies injury to the entire posterolateral corner complex including the popliteus tendon and popliteofibular ligament. The common peroneal nerve wraps around the fibular neck immediately distal to the LCL insertion and is injured in approximately 25 percent of posterolateral corner injuries, producing foot drop.
LCL and popliteofibular ligament complex disruption from varus contact force producing combined posterolateral knee instability, often with common peroneal nerve injury requiring careful surgical reconstruction.
