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Lateral (outer) knee pain

Expert reviewer, Mr Damian McClelland, Trauma and Orthopaedic Consultant, and Clinical Director for Musculoskeletal Services at Bupa
Next review due July 2024

Outer knee pain or lateral knee pain is pain on the outer side of your knee. That is, on the right side of your right knee or the left side of your left knee. It might just affect your knee or the pain may spread up your thigh.

A diagram by Bupa of where outer knee pain is located

Types of outer knee pain

There are several health conditions that may cause outer knee pain.

Iliotibial band syndrome develops if a band of connective tissue rubs on the outside of your knee. The iliotibial band is a thick band of fibrous tissue that runs from your hip to below your knee on the outside of your leg. If you bend and straighten your leg a lot, it can cause this tissue to become sore and inflamed where it passes over the bottom of your thigh bone and meets your knee. This type of problem is most common in runners and cyclists.

Lateral collateral ligament injury is caused by a blow to the inside of your knee, which stretches the outside (lateral side) of your knee and injures the ligament. A ligament is a band of tissue that connects one bone to another. The lateral collateral ligament runs down the outer side of your knee.

Meniscal injury is damage to the meniscal cartilages inside your knee. These cartilages act like shock absorbers and may tear when you twist your knee with your foot still on the ground. This type of injury is common in sports where you have to change direction suddenly – for example, football and skiing. It can also happen in jobs that involve lifting and twisting – for example, construction or manual labour. The meniscus can tear without any particular injury as you get older because of wear and tear.

Anterior cruciate ligament injury is overstretching or tearing a ligament that runs across your knee from your thigh to your shin bone. A tear may be either complete or partial. The injury happens suddenly if you twist or rotate your knee. It can happen if you suddenly slow down, stop or change direction and is nearly always linked with sports.

Osteoarthritis of the knee is a common cause of knee pain. The smooth, shiny cartilage that lines your knee joint becomes worn and rough. This causes pain and damages your knee over time. It mostly affects people over 50. The older you are, the more likely you are to get it.

Causes of outer knee pain

Outer knee pain may be caused by a number of things. For example, you may have some damage inside your knee or swelling of a band of fibrous tissue that runs down from your hip to your knee. These things may happen because you:

  • have a sports injury
  • overused your knee during exercise
  • get older

Outer knee pain is more common if:

  • you’re a distance runner or run a long distance each week
  • you’re an inexperienced runner or suddenly increase the distance and frequency of your runs
  • you cycle
  • you have an injury that pushes your knee outwards (away from your other leg)
  • you do activities that involve twisting your knees or squatting
  • you’re ‘knock-kneed’ or ‘bow-legged’, both of which place a strain on your outer knee
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Symptoms of outer knee pain

The symptoms of outer knee pain will vary depending on the type of injury you have. Outer knee pain may feel dull and your knee may ache, or the pain can be sharp and limited to one area. You may have swelling from fluid that collects, or your knee may click or lock (get stuck in one position).

If you have iliotibial band syndrome, you may have pain all over the outside of your knee or the pain may be sharp and in one area. If your injury is mild, you might notice the pain come on after a certain time or distance when you’re running, for example. And it may get better when you stop. If your injury is more severe, it might be painful to walk or even sit with your knee bent.

If you have a lateral collateral ligament injury, the outside of your knee will be painful. This ligament helps to keep your knee stable, so you may feel as if your knee is going to give way. You may have swelling around your knee, or pins and needles in your foot. You might find the pain is worse when you walk or run on uneven ground.

Symptoms of a torn meniscal cartilage include pain and your knee may also feel stiff, and lock or catch. There may be some swelling that may gradually get worse and you may find it difficult to fully straighten your leg. Pain can come and go, as can the swelling.

Pain from an anterior cruciate ligament injury will be sudden and you may hear a pop. Your knee is likely to swell from internal bleeding and may feel as if it’s going to give way.

Osteoarthritis usually causes pain when you bear weight on it, and gets better when you rest. Your knee may be stiff and you might not be able to move it as well first thing in the morning or after you sit for a while. This usually eases once you start moving around. You may also have some swelling in your knee.

Diagnosis of outer knee pain

Your doctor will examine your knee and ask about your medical history and symptoms, including:

  • the type of pain you have, when it started and if it comes and goes
  • how active you are
  • any activity, accident or injury that could have caused it

They may suggest an X-ray or a magnetic resonance imaging (MRI) scan, but this isn’t always necessary. Your doctor may be able to diagnose the injury from examining you and asking about your symptoms.

If you have cartilage or ligament damage, your doctor may suggest a procedure to look inside your knee. This is called an arthroscopy (keyhole surgery). Your doctor will make a small cut in your knee and pass a thin tube with a camera on the end through the cut. As well as diagnosing the problem, your doctor can also repair or remove damaged tissue.

Self-help for outer knee pain

If you injure your knee, you should follow the POLICE and HARM procedures. POLICE stands for protect, optimal loading, ice, compression and elevation – things you should consider doing if you have injured your knee. And HARM stands for heat, alcohol, running and massage – things that you should avoid for a bit so you don’t damage your knee further.

If you can’t put weight on your leg, you may need crutches. Try to keep your joints moving unless it is painful to do so.

If your injury is mild, you may not need to see a doctor or physiotherapist. But do go and see a doctor or physio if:

  • you cannot put weight on your leg
  • you have severe pain even when you don’t put any weight on it
  • your knee buckles or clicks or locks
  • your knee looks deformed or misshapen
  • your knee is hot, red, very swollen or you have a fever
  • you have pain, swelling, numbness, tingling or your calf looks blue
  • your pain doesn’t settle over a few days

Treatment of outer knee pain

Treatment for outer knee pain will depend on what condition is causing the pain.

For information on how to treat outer knee pain, please see the relevant page for each type of knee condition. For example, treatments for:

Frequently asked questions



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  • Discover other helpful health information websites.

    • Soft tissue knee injury. Medscape. emedicine.medscape.com, updated 20 February 2016
    • Iliotibial band syndrome. BMJ Best Practice. bestpractice.bmj.com, last reviewed 3 May 2021
    • Assessment of knee injury. BMJ Best Practice. bestpractice.bmj.com, last reviewed 20 April 2021
    • Lateral collateral knee ligament injury. Medscape. emedicine.medscape.com, updated 30 November 2020
    • Personal communication, Mr Damian McClelland, Trauma and Orthopaedic Consultant and Clinical Director for Musculoskeletal Services at Bupa, 6 July 2021
    • Knee sprains and meniscal injuries. MSD Manuals. msdmanuals.com, last full review/revision March 2021
    • Meniscal tear. BMJ Best Practice. bestpractice.bmj.com, last reviewed 21 April 2021
    • Anterior cruciate ligament injury. BMJ Best Practice. bestpractice.bmj.com, last reviewed 3 May 2021
    • Knee ligament injuries. Patient. patient.info, last edited 15 February 2017
    • Anterior cruciate ligament injury. Medscape. emedicine.medscape.com, updated 26 February 2021
    • Osteoarthritis. BMJ Best Practice. bestpractice.bmj.com, last reviewed 3 May 2021
    • Osteoarthritis. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised June 2018
    • Meniscus injuries. Medscape. emedicine.medscape.com, updated 12 October 2018
    • Soft tissue knee injury. Medscape. emedicine.medscape.com, updated 20 February 2016
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    • Meniscal tears and other knee cartilage injuries. Patient. patient.info, last edited 1 February 2017
    • Preparing for a knee arthroscopy. Royal College of Anaesthetists. www.rcoa.ac.uk, accessed 3 June 2021
    • Knee surgery. American Society of Anesthesiologists. www.asahq.org, accessed 3 June 2021
    • Bleakley CM, Glasgow P, and MacAuley DC. PRICE needs updating, should we call the POLICE? British Journal of Sports Medicine 2012; 46:220–21. doi: 10.1136/bjsports-2011-090297
    • First aid in general practice. Patient. patient.info, last edited 15 February 2017
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    • Iliotibial band friction syndrome. Medscape. emedicine.medscape.com, updated 26 May 2020
  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, July 2021
    Expert reviewer, Mr Damian McClelland, Trauma and Orthopaedic Consultant, and Clinical Director for Musculoskeletal Services at Bupa
    Next review due July 2024

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