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Knee

LCL/PCL Tear

What is the lateral collateral ligament (LCL) of the knee?

The LCL is a ligament on the outer (lateral) side of the knee that connects the femur (thigh bone) to the fibula (outer shin bone). It helps stabilize the knee and prevents it from buckling outward.

The PLC is a complex group of structures on the back and outer side of the knee. It includes the LCL, popliteus tendon, and other soft tissues that work together to provide stability, especially during twisting and side-to-side movements.

Together, the LCL and PLC prevent the knee from shifting outward (varus instability) and protect it during rotation or sudden directional changes. They are essential for knee stability during walking, running, and pivoting.

These injuries involve sprains or tears to the LCL and/or PLC structures. They may occur in isolation or along with other ligament injuries (like ACL or PCL tears). Severe injuries can lead to significant instability and difficulty with walking.

Symptoms include pain on the outer side of the knee, swelling, instability, and difficulty walking—especially when turning or going downhill. Patients may also feel their knee shift or “give way.”

These injuries often occur from a direct blow to the inner knee, twisting injuries, or falls. High-energy trauma, such as from sports or car accidents, can also damage the PLC and are frequently part of multi-ligament knee injuries.

Diagnosis involves a physical exam to test side-to-side and rotational knee stability. X-rays rule out bone injury, while MRI is used to assess soft tissue damage. In high-energy injuries, vascular studies may also be needed to rule out artery injury.

Mild LCL sprains may be treated with rest, bracing, and physical therapy. More severe or complete tears — especially involving the PLC — often require surgical repair or reconstruction to restore stability and prevent long-term joint damage.

Recovery typically takes 6 to 12 months, depending on the severity of the injury and whether other ligaments were involved. Bracing and limited weight-bearing are needed early on. Physical therapy focuses on gradually restoring motion, strength, and stability.

At a Glance

Sachin Allahabadi, MD

  • Board-Certified & Fellowship-Trained Sports Medicine Surgeon
  • Expertise in Minimally Invasive Knee & Shoulder Surgeries
  • Assistant Professor of Clinical Orthopaedic Surgery, Houston Methodist Hospital & Weill Cornell Medical College
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