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LCL (FCL) Tears and Treatment

Description of LCL Tear (FCL Tear)
The lateral collateral ligament (LCL), also called the fibular collateral ligament (FCL), is the main structure on the lateral (outside) portion of the knee to prevent the knee from gapping open (varus gapping). The term fibular collateral ligament (FCL) is more anatomically correct, but this ligament is more commonly referred to as lateral collateral ligament (LCL). It is a thin, round, stout ligament, which courses from the femur down to the lateral aspect of the fibular head.

An FCL injury can occur with sudden stops and starts, a blow to the inside of the knee, or a contact or noncontact hyperextension injury. Sometimes, a FCL tear can go undiagnosed for a few weeks before an athlete notices instability. Oftentimes, there is not significant knee swelling when occurring in isolation without other ligament injury. More commonly, an FCL tear occurs in conjunction with a ACL or PCL injury, but can occur in isolation.

Symptoms of LCL Tear (FCL Tear)

  • Mild swelling and pain – no obvious deep swelling within the knee

  • Difficulty stopping and cutting

  • Instability of the knee shifting side-to-side

  • Many athletes note that they cannot stop and cut towards the side where they have the LCL tear, due to a feeling of instability of the knee shifting side-to-side. Unfortunately, due to the unstable nature of the lateral compartment of the knee with two convex surfaces opposing each other, grade III lateral collateral ligament tears usually do not heal, and can lead to further instability.


Diagnosis of LCL Tear (FCL Tear)
The diagnosis of an FCL tear is made through a combination of physical examination and X-rays. In most circumstances, the athletes will complain of a feeling of side-to-side instability and have varus gapping on the physical exam. Varus stress x-rays are very useful to determine the amount of gapping to determine if it is a complete or partial tear and are highly recommended to be performed. Studies have reported that greater than 2.7 millimeters of side-to-side gapping is consistent with a complete tear of the FCL and a reconstruction should be considered. It is important to note that an MRI scan can be inaccurate – especially in cases of a chronic situation where the LCL heals improperly – that is why it is important to properly analyze the pathology.


Treatment for LCL Tear (FCL Tear)
In the acute situation, an FCL reconstruction is recommended using a tendon autograft or allograft. Dr. Ziegler utilizes an anatomic technique that has been developed and biomechanically and clinically validated. In patients with a chronic injury, it is important to assess their overall alignment. If they are in varus alignment (bow legged), there is a very high risk that the FCL reconstruction would stretch out if the varus alignment is not concurrently fixed. Thus, a proximal tibial opening wedge osteotomy would be indicated.


The outcomes of FCL reconstructions are excellent. Patients should not place weight on the injured leg for 6 weeks and then may progress off of crutches and start the use of a stationary bike starting at week 6. They should avoid side-to-side activities or step-up activities for 6 months. Those who follow the rehabilitation program demonstrate excellent return of stability and can usually return to full function within 6-7 months after surgery.

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