What Is LCL Injury?

The lateral collateral ligament (LCL) is on the outer side of your knee and runs from the top part of the fibula (the bone on the outside of the lower leg) to the outside part of the lower thigh bone. The ligament helps keep the outer side of your knee joint stable.

A lateral collateral ligament (LCL) injury is usually caused by pressure or an injury that pushes the knee joint from the inside, which results in stress on the outside part of the joint.

The symptoms of a tear in the lateral collateral ligament can include:

  • Knee swelling
  • Locking or catching of your knee with movement
  • Pain or tenderness along the outside of your knee
  • A knee that gives way, or feels like it is going to give way, when it is active or stressed in a certain way

Diagnosis of LCL Injury

Your health care provider will first conduct a lateral collateral ligament test to reveal any looseness in the ligament. This test involves bending the knee to 25 degrees and placing pressure on the inside surface of the knee.

Other tests may include:

  • Knee joint x-rays
  • Knee MRI

Treatment at Penn

LCL injuries require prompt first aid, including applying ice, using pain relievers and elevating the knee above heart level. It is rare that the LCL is the only ligament injured, which is why it’s important to seek medical help immediately. When injuries to other ligaments also occur, surgery is needed to prevent future instability of the knee.

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