Knee injury - lateral collateral ligament (LCL)

Alternative names
LCL injury; Lateral collateral ligament (LCL) injury of the knee

LCL injury is a stretch, partial tear, or complete tear of the lateral collateral ligament (LCL) of the knee. (The term “lateral” means the ligament is on the outside of the knee.)

A lateral collateral ligament test may reveal a looseness in the ligament. This involves bending the knee to 25 degrees and placing pressure on the inside surface of the knee.

Other tests may include:

  • a knee MRI  
  • a knee joint X-ray  
  • a knee joint X-ray with stress applied

The lateral collateral ligament (LCL) extends from the top-outside surface of the fibula (the bone on the outside of the lower leg) to the bottom-outside surface of the femur (the thigh bone). The ligament stabilizes the knee on the outside of the joint.

The LCL is usually injured by pressure placed on the knee-joint from the inside, resulting in stress on the outside of the joint (varus stress).


  • knee pain or tenderness along the outside of the kneecap  
  • knee swelling may be present  
  • knee instability (giving way)

First Aid

Initial treatment of an LCL injury includes ice to the area, elevation of the joint (above the level of the heart), nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibruprofen or aspirin, and limited physical activity until the pain and swelling subside.

Immobilization for a period of time is generally necessary for pain relief and healing. Physical therapy is usually helpful to regain knee strength and flexibility.

Surgery for isolated LCL injuries is not generally necessary. However, this ligament is commonly injured during significant trauma, including knee dislocations. When injuries to the LCL occur with other ligament injuries, repair is necessary to prevent future instability of the knee.

Call immediately for emergency medical assistance if
Call your health care provider if you injure your knee and symptoms of LCL injury occur.

Call your health care provider if you are being treated for an LCL injury and you notice increased instability in your knee, if pain or swelling return after they initially subsided, or if your injury does not resolve with time.

Also call if you reinjure your knee.

Use proper technique when exercising or playing sports. Many cases may not be preventable.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.