The lateral collateral ligament is also called the fibular collateral ligament. It is a strong, cord-like tissue found on the lateral or outer side of the knee and connects the thigh bone (called femur) to the small bone in the lower leg (called fibula).
The LCL is responsible for resisting various stresses placed on the inner side of the knee and prevents outside rotation of the lower leg. It provides stability, especially on the outer side of the knee. Together with the medial collateral ligament (MCL), they control side-to-side and rotational knee movements.
LCL injuries are less frequent than MCL injuries. Because of its location, the lateral collateral ligament is seldom injured alone. It is usually accompanied by injuries to the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and other knee soft tissues.
An LCL injury can be classified as follows:
- Mild or grade I: LCL is slightly stretched, but the knee is stable.
- Moderate or grade II: LCL is partially torn, and there is possible knee instability.
- Severe or grade III: LCL is completely torn, and there is difficulty putting weight on the affected leg.
LCL Injury Symptoms
Symptoms of LCL injury depend on the extent of the damage and whether other structures of the knee are injured as well. One or more of the following symptoms may be experienced:
- Pain and tenderness on the outer edge of the knee
- Swelling on the outer side of the knee.
- Bruising on or around the knee
- Knee instability or feeling that the knee may give way during walking or standing.
- Difficulty putting weight on the injured leg.
- Locking of the knee during movement.
- Limited range of motion
- Weakness of thigh muscles or difficulty straightening the knee
- Weakness or numbness felt on foot, which occurs when the peroneal nerve that runs near the LCL is stretched or compressed due to swelling.
Causes of LCL Tear
The most common cause of LCL injury is an external blow to the inner side of the knee, which pushes the knee outwards. If the force is too great, it may cause the LCL to tear and damage other structures in the knee joint completely.
LCL injuries are usually contact injuries, but non-contact injuries may also occur. This type of injury is usual in sports such as
- That require frequent and sudden stops and turns such as skiing
- Those that involve jumping and twisting, such as basketball
- Those in which violent impacts occur, such as in football and hockey.
- Also, wrestlers may injure their LCL during sudden outward twisting while lifting.
- Lastly, the LCL may be injured due to repeated stress, which reduces the normal elasticity of the ligament, preventing it from stabilizing the knee.
A comprehensive physical examination and patient history are necessary to obtain vital information to diagnose the knee injury. The injured knee will be visually observed and palpated, and compared to the uninjured knee. The range of movement of the knee and the gait pattern will be thoroughly assessed to determine the severity of the injury.
Further, since isolated LCL injury is unusual, special tests may be done to examine if there is associated damage to other ligaments, menisci, and soft tissues.
Although an X-ray will not determine damage to the LCL, the doctor may require this to check for the presence of any bone fractures. Also, a magnetic resonance imaging (MRI) scan may be ordered to accurately determine the LCL tear severity and assess if there is damage to other structures in the knee.
A mild or grade I (slight stretch) injury to the LCL may only require rest, application of ice to the injured area [for 15 to 20 minutes ] every 2 hours, elevating the knee above the heart, and over-the-counter pain relievers to reduce the pain; however, it is still best to consult a physician to treat and manage the injury effectively.
The doctor may require the patient to wear a brace for approximately 72 hours, depending on the pain and swelling and how effective it will be to reduce them. The brace will allow forward and backward movements of the knee, but it will prevent side-to-side and rotational movements.
Once the pain and swelling are minimal, physical therapy may begin. A rehabilitative program developed by a physical therapist provides the patient with exercises to help restore the strength and range of motion of the injured knee. Flexibility training, strengthening exercises, and general body conditioning such as aerobic exercises are some of the exercises that may be given. Soreness and swelling may ensue with exercise; to prevent this, lower the intensity and gradually progress the exercise.
LCL tear is not as good as MCL tear in terms of healing; thus, it may require surgical intervention for repair. Arthroscopic surgery, which is less invasive and allows faster recovery, may be needed for mild tears. The LCL that is torn on its attachment to the bone (either on the thigh bone or fibula bone) will be reattached by the surgeon using large stitches or a metal bone staple. If the tear occurred in the middle or near the middle of the ligament, the ends would simply be sewn together.
Severely damaged LCL tears that are difficult to repair and involve damage to other soft tissues will require reconstruction surgery which is more invasive and requires longer recovery time. An “open-knee procedure” may be done in which a graft from a thigh tendon (quadriceps or hamstrings) will be collected by the surgeon and will be used to reconstruct the LCL.
Healing of LCL injury is usually within four to six weeks, depending on the extent of the damage, but it may take up to months for severe cases that require surgery. Once completely healed, there is no more pain, and the range of motion and strength of leg muscles are back to normal, the patient can return to regular activities and sports.
The best thing to do at home for an LCL injury is rest and avoid placing weight on the injured leg. Mild or grade I injuries can be easily managed at home through application of ice to the injured area [for 15 to 20 minutes ] every 2 hours, placing an elastic band and elevating the injured leg to prevent further swelling, use of crutches to limit the weight placed on the injured leg, and pain medications such as Ibuprofen.
Previous injury to the knee predisposes one to re-injury; therefore, precautionary steps must be taken to prevent tearing the LCL again or damaging other structures of the knee. The following can be done to prevent LCL injury:
- A knee brace could be worn during sports-related activities to provide additional support to the knee and prevent excessive side to side and rotational knee movements.
- Always practice correct techniques such as proper positioning and leg alignment during jumping, turning, and lifting, which are common in sports and recreational activities.
- Perform warm-up activities such as stretching and conditioning exercises before participating in sports activities. This will help in preparing the muscles and joints before engaging in movements.
- For athletes, ensure that related training and conditioning are routinely done to ensure that the body is accustomed to the stress it receives during sports activities.
- American Academy of Physical Medicine and Rehabilitation: “Medial and lateral collateral ligament injuries.”
- Herzog MM, et al. (2019). Epidemiology of ankle sprains and chronic ankle instability.
- Sampsell E. (2021). Personal interview.
- Sandow E. (2021). Personal interview.
- Schiftan GS, et al. (2014). The effectiveness of proprioceptive training in preventing ankle sprains in sporting populations: A systematic review and meta-analysis.
- Sports Health: “Lateral Collateral Ligament (LCL) Injuries,” “The LCL Injury Grading System,” “Nonsurgical Treatment for LCL (Lateral Collateral Ligament) Tears,” “Surgical Treatment for LCL (Lateral Collateral Ligament) Tears,” “LCL Tear Prevention.”
- Sprained ankle. (2016).