Lateral collateral ligament (LCL) injury

Expert reviewer, Mr Damian McClelland, Trauma and Orthopaedic Consultant, and Clinical Director for Musculoskeletal Services at Bupa
Next review due November 2023

The lateral collateral ligament (LCL) is one of the ligaments inside your knee. The LCL lies on the outer side of your knee joint, and connects your thigh bone (femur) to the small bone in your lower leg (fibula). An LCL injury can be a partial or complete tear, or a stretched ligament.

An image showing the different parts of the knee

About lateral collateral ligament injury

The LCL is sometimes called the fibular collateral ligament. Along with the other ligaments in your knee, your LCL keeps your knee stable. Your LCL and your medial collateral ligament (MCL) control the sideways movement of your knee.

When the knee ligament is stretched but not torn, this is called a sprain. Sprains are given different grades depending on how severe they are. If your LCL injury is severe, it may be associated with injuries to the ligaments and tendons in your knee. For example, your anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), as well as other parts of your knee.

Causes of lateral collateral ligament injury

A lateral collateral ligament (LCL) injury is usually caused by your knee being pushed outwards (away from your other knee). This may happen if you have a blow to the inside of your leg, which can happen during contact sports such as football. You can also injure your LCL by twisting on the side of your foot, or extending your knee beyond its normal range of movement.

You may also injure your LCL along with other ligaments in your knee if you have a major accident. For example, if you fall from a height or have a car accident.

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Symptoms of lateral collateral ligament injury

The symptoms of an LCL injury may depend on whether you also damage other parts of your knee. You’ll probably have some pain on the outside of your knee. And you may have some bruising and swelling in the area of your injury.

Depending on the severity of your injury, your knee may also feel a little unstable when you move it from side to side, and feel as if it’s going to give way. You might find it difficult to walk on uneven ground or up and down stairs.

It’s common to damage a nerve in your knee at the same time as your LCL. If this happens, you may have some numbness and weakness around your foot and ankle.

Self-help for lateral collateral ligament injury

If you injure your knee, you should follow the POLICE procedure to manage any type of soft tissue injury to your knee. POLICE stands for protect, optimal loading, ice, compression and elevation.

Additionally, there are certain things you should avoid in the first three days after your injury so you don’t damage your knee further. These can be remembered as HARM, which stands for heat, alcohol, running and massage.

To find out more about POLICE and HARM, you can visit our page on what to do if you injure your knee.

If you’re having difficulty bearing weight on your knee, you may need to use crutches or wear a brace to support you for a while. Your doctor or physio will explain how long you’ll need to use these for.

Treatment for lateral collateral ligament injury

You’ll usually need to go to A&E with this kind of injury, where they’ll examine you and take some X-rays of your knee. They may then refer you to an acute knee clinic, which will organise any investigations and treatment you need.

The treatment you’re offered for your LCL injury will depend on how severe the damage is, and if you’ve injured any other parts of your knee. The initial treatment will be to control your pain and swelling using the POLICE and HARM self-help measures (see above). Further treatments include knee bracing, physiotherapy, medicines, and sometimes, surgery.

You may see an orthopaedic surgeon (a doctor who specialises in bone surgery) or a sports medicine professional, such as a sports doctor or a physiotherapist. There are different treatments that your doctor or physiotherapist may suggest, and a lot that you can do yourself to help your recovery.

Medicines for lateral collateral ligament injury

You can take over-the-counter painkillers, such as paracetamol or ibuprofen, to help relieve any pain. Your doctor may prescribe stronger painkillers if your pain is really bad. As well as easing your pain, non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen may help to reduce inflammation and swelling. Always read the patient information that comes with your medicine, and if you have questions, ask your pharmacist or GP for advice.

Physiotherapy for lateral collateral ligament injury

Your physiotherapist will carefully assess your knee and then plan a programme of rehabilitation exercises to suit your individual needs. The physiotherapy programme will be designed to help your knee recover its full range of movement and its strength and stability. This should help you get full function back in your knee and return to your usual sports and activities. Make sure you do the exercises as this is an important part of your recovery. Often, treatment with physiotherapy and leg bracing will be all you need if you have a LCL injury. You may recover and get back to your usual activities and sports after about four to six weeks but ask your physiotherapist for specific advice for you.

Surgery for lateral collateral ligament injury

Most people with a mild or moderate LCL injury won’t need surgery. If your LCL injury is more severe, it’s likely that you’ll have damaged other parts of your knee too. If this happens to you, surgery is likely the best option to repair your LCL and help to restore stability in your knee.

It can take about a month to recover from surgery and to be able to put weight on your knee. Ask your doctor about the pros and cons of surgery, and how it might help you.

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Related information

    • Acute knee injuries. Brukner & Khan’s Clinical Sports Medicine: Injuries, Volume 1, 5th ed (online). McGraw-Hill Medical., published 2017
    • Collateral ligament injuries. American Academy of Orthopaedic Surgeons., last reviewed March 2014
    • Knee ligament injuries. PatientPro., last edited 15 February 2017
    • Lateral collateral knee ligament injury. Medscape., updated 9 March 2015
    • Treatment of sports injuries. Brukner & Khan’s Clinical Sports Medicine: Injuries, Volume 1, 5th ed (online). McGraw-Hill Medical., published 2017
    • Knee pain – assessment. NICE Clinical Knowledge Summaries., last revised July 2017
    • Sprains and strains. NICE Clinical Knowledge Summaries., last revised April 2020
    • Treatment for knee pain. Chartered Society of Physiotherapy., last reviewed 26 March 2020
  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, November 2020
    Expert reviewer, Mr Damian McClelland, Trauma and Orthopaedic Consultant, and Clinical Director for Musculoskeletal Services at Bupa
    Next review due November 2023