The knee joint contains two cruciate ligaments (ACL and PCL), the medial collateral ligament (MCL) and the lateral collateral ligament (LCL). The LCL is also called the fibular collateral ligament (FCL). The FCL is a thick band of tissue on the outside of the knee that provide side-to-side knee stability. The FCL runs along the outside of the knee and connects the thighbone (femur) to one of the leg bones (fibula).
The MCL and FCL work together during flexion and extension of the knee to stabilize the knee. Damage to the FCL causes instability during side-to-side motion.
What causes tears to the FCL?
Significant force is usually necessary to tear this ligament. It is often injured during a fall, during recreational activities or a direct blow to the inside of the leg. All of these mechanisms can cause the knee to bow outward (a varus force). The force of the fall or blow pushes the knee from the medial or inner side of the joint, thereby damaging the outside (lateral) knee structures, including the FCL. The FCL can also be injured by hyperextension of the knee, when the knee is forced backward. The FCL most commonly tears in conjunction with an injury to the ACL and/or PCL. An FCL injury could be a partial or complete tear.
What are the symptoms of an FCL tear?
- Swelling, bruising and pain on the outside of the knee
- Knee stiffness
- Knee instability
- Knee buckling
- Difficulty walking
- Damage to the peroneal nerve can cause foot drop or numbness and tingling on top of the foot.
Who is at risk?
Anyone with a prior injury to a knee ligament who has chronic instability is at risk for additional damage to the FCL. All athletes, especially those who participate in sports involving cutting/pivoting (skiing, soccer, basketball, lacrosse), are at risk as well.
How is it diagnosed?
Dr. Godin will ask about your medical history, how the injury occurred and your symptoms. He will conduct a thorough physical examination to test the FCL. X-rays will be ordered to rule out fractures. Stress x-rays are very important to identify damage to the collateral ligaments. An MRI may be ordered, especially when there are multiple injuries.
What are the treatment options?
An isolated tear and low grade sprains can be treated with non-operative measures including rest, ice, compression, elevation, bracing, over the counter pain management, and physical therapy. Recovery usually takes 6 – 8 weeks. Once full knee range of motion is restored, and the knee is stable, you may need to wear a functional brace if you intend to return to sports activities. Continued pain and swelling indicate a need for surgical repair or reconstruction.
A significant tear of the FCL and injury to other knee structures will require surgery. Surgery to reconstruct the FCL will involve rebuilding the ligament using a graft. The tissue will be taken from either a cadaver (an allograft) or from your own body (an autograft) often by using one of the hamstring tendons. Weight bearing after surgery will be restricted for about 6 weeks .
Rehabilitation after surgery is intended to control pain, ensure safe weight bearing, and improving range of motion and strength. Return to sport typically takes 6 months.
Dr. Jonathan Godin whose specialty is complex knee injuries. He is an internationally renowned orthopedic surgeon at Vail Orthopedic Surgery. When you or a loved one suffers with an orthopedic injury, contact Dr. Godin at to schedule a consultation where you will receive the correct diagnosis and state-of-the-art treatments.