Lateral (outer) knee pain


Expert reviewer, Mr Damian McClelland, Consultant Trauma and Orthopaedic Surgeon
Next review due March 2022

Outer knee pain may also be called lateral knee pain (LKP). Lateral simply means outer side. It refers to pain on the outer side of your knee (so the right side of your right knee, and the left side of your left knee).

You may have pain on the outside of your leg just around your knee or pain that spreads up your thigh. The pain may come from damage inside the knee itself, or from swelling of a band of fibrous tissue that runs down from the hip to the knee.

A diagram by Bupa of where outer knee pain is located

Causes of outer knee pain

There is no single cause, but there are several reasons why you may have outer knee pain. It’s more common:

  • in distance runners or people who run a long distance each week
  • in runners who are inexperienced or suddenly increase the distance and frequency of their runs
  • in cyclists
  • after an injury that pushes the knee outwards (away from the other leg)
  • in those who do activities that involve twisting or pivoting of the knees
  • in people who tend towards being ‘knock-kneed’ or ‘bow-legged’, placing a strain on the outer knee

Conditions associated with outer knee pain

There are several medical conditions linked to outer knee pain. Generally, they are caused by damage from a sports injury, from overusing the knee during exercise or from getting older.

Iliotibial band syndrome is caused by a band of connective tissue rubbing on the outside of the knee. The iliotibial band is a thick band of fibrous tissue that runs from the hip to below the knee on the outside of the leg. Frequent bending and straightening of the leg can cause this tissue to become sore and inflamed where it passes over the bottom of the thigh bone, where it meets the knee. This type of problem is most common in runners and cyclists.

Lateral collateral ligament injury is caused by stretching or tearing of the band of tissue that connects the thigh bone to the shin bone (a ligament is a band of tissue that connects one bone to another). The lateral collateral ligament runs down the outer side of the knee. This injury can be seen in skiers, footballers or basketball players.

Meniscal injury is damage to the meniscal cartilages inside the knee. The meniscus cartilages act like shock absorbers and may tear when you twist your knee with your foot still on the ground. So, this type of injury is common in sports where you have to change direction suddenly, such as football and skiing. It can happen in occupations involving lifting and twisting, such as construction or manual labouring. The meniscus can also tear in older people because of wear and tear and without any particular injury.

Anterior cruciate ligament injury is overstretching or tearing of this ligament, which runs across the knee from the thigh to the shin bone. A tear may be either complete or partial. The injury occurs suddenly, caused by twisting or rotating the knee. It can happen if you suddenly slow down, stop or change direction and is nearly always associated with sports.

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

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Symptoms of outer knee pain

Pain may be dull and aching, or sharp and localised. You may have swelling from fluid collecting or your knee may click or lock (get stuck in one position).

With iliotibial band syndrome, you may have pain all over the outside of your knee or the pain may be sharp and in one area. You may get pain when running and when doing anything that causes you to bend and straighten your leg repeatedly, such as cycling or going up and down stairs.

Lateral collateral ligament injury causes pain over the outside of the knee, which may focus on the mid-point of the knee joint. This ligament helps to keep the knee stable, so you may feel as if your knee is going to give way. You may have swelling around the knee or pins and needles in the foot. Some people find the pain worse when walking or running on uneven ground.

Symptoms of a torn meniscus cartilage generally come on up to a day after the initial injury. Pain and swelling may increase and you may have difficulty fully straightening your leg. Pain can come and go. Swelling may improve over days or weeks but get worse again after exercise. The knee may also feel stiff and lock or catch.

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

Osteoarthritis usually causes pain when you’re bearing weight, which is relieved by rest. You may have stiffness and loss of movement first thing in the morning or after sitting for a while. This usually eases once you start moving around. You may also have some swelling over your knee.

Diagnosis of outer knee pain

Your doctor will examine your knee and take a history, asking about:

  • the type of pain you have, when it started and whether 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 is not always necessary. The examination and your history may be enough to diagnose you.

If you have cartilage or ligament damage, your doctor may suggest a procedure to look inside your knee, called an arthroscopy (often referred to as ‘keyhole surgery’). This involves making a small cut in your knee and inserting a thin tube with a camera on the end. As well as diagnosing the problem, the procedure can also be used to repair or remove damaged tissue. Most knee operations (apart from joint replacement) are now done using keyhole surgery.

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Managing outer knee pain

Immediately after an injury, you can help yourself by resting your leg, using an ice pack and taking painkillers, such as ibuprofen. If you can’t put weight on your leg, you may need crutches. Avoid twisting or bending the knee as far as possible.

If your injury is mild, you may not need to see a doctor or physiotherapist, but you should if:

  • you cannot put weight on the affected leg
  • you have severe pain, even when not bearing weight
  • your knee buckles, clicks or locks
  • your knee is deformed or misshapen
  • your knee is hot, red or very swollen or you have a fever
  • you have pain, swelling, numbness, tingling, or a bluish discoloration in your calf
  • you’re still in pain after three days

Treatment of outer knee pain

The treatment that you have for your outer knee pain will depend on what condition is causing the pain.

For information on treatments, please see the relevant knee condition page.


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  • Reviewed by Alice Windsor, Specialist Health Editor, Bupa UK Health Content Team, March 2019
    Expert reviewer, Mr Damian McClelland, Consultant Trauma and Orthopaedic Surgeon
    Next review due March 2022



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