Lateral Collateral Ligament (LCL) Injury

The Lateral Collateral Ligament (LCL), also known as the fibular collateral ligament, is on the outer side of your knee joint and connects the thigh bone (femur) to the shin (tibia). Its function, along with the Medial Collateral Ligament, is to provide stability to the knee joint, by preventing too much sideways movement. The LCL itself prevents excessive outward movement of the knee (known as “Varus” stress). It also helps with stabilising the knee to prevent excessive forward/backward movement, alongside the cruciate ligaments.

Injury to the LCL is rare in relation to other knee ligament injuries and accounts for only 6% of all knee injuries. If it is injured, it is typically accompanied with other structural/ligament injuries, rather than in isolation.

Injury can occur due to a direct force/blow to the inside of the knee, forcing the knee outward (Varus) and putting excessive load on the LCL. This is more common if the foot is planted at the time of impact, and this can also occur without contact e.g. studs caught in turf/excessive movement skiing. Injury can also occur due to hyper-extension of the knee.

If you have injured your LCL, you may present with some of the following:

• Pain on the outside aspect of the knee.

• Tenderness to touch on the outside of the knee.

• Swelling on the outside of the knee.

• Instability of the knee joint (feelings of it “giving way”).

• Stiffness of the knee/reduced movement.

• Possible limp.

• Hearing a ‘pop’ sound at the time of injury.

Grade of LCL sprains, as with any other ligament injury, are divided into 3 categories of severity:

Grade 1: The least severe. A mild sprain involving less than 10% of the ligament fibres. You are likely to feel discomfort and possibly mild swelling, but will not have laxity/instability of the joint, and may even feel able to continue most normal activities. Typically return to full sport is within 4-6 weeks.

Grade 2: An increased portion of the ligament fibres will be ruptured compared to grade 2, and you will have pain, with possible swelling, and some instability. Typically return to sport is around 8-12 weeks.

Grade 3: Most severe. Full rupture (tear) of the ligament. Severe pain. Likely to involve instability of the knee joint. Difficulty moving the knee. Return to sports can be 3 months +.

Physiotherapist examination can help ascertain the degree of injury, and therefore the next suitable course of action.

Initial treatment for this type of injury will depend of the extent of damage. Initially ice and rest are used to control the swelling and help pain management. Some lesser injuries may simply require a short period of relative rest, and phased return to activity with some exercises, with little more concern. A more extensively damaged ligament may require bracing, and the use of crutches in the beginning, to help healing.

Physiotherapy treatment is then essential for the rehabilitation of more severe LCL injuries. It is important to regain full movement of the knee joint via stretching exercises, regaining power around the knee, particularly the quadriceps muscles, and improving stability/proprioception at the knee joint; all to help to return to full function, and help prevent future issues.

Surgery is rarely required for LCL injuries in isolation but can be an option particularly if more than one ligament of the knee is affected, and if the knee joint is still particularly unstable after a period of physiotherapy. It will also be dependent on the desired level of function/sport.