There is a fluid-filled sac, called a bursa, between the bone and the tendon on the outside part of your leg. The sac provides lubrication between the tendon and the bone. The rubbing of the tendon can cause pain and swelling of the bursa, the tendon, or both.

This injury often affects runners and cyclists. Bending the knee over and over during these activities can create irritation and swelling of the tendon.

Other causes include:

• Being in poor physical condition
• Having a tight ITB
• Poor form with your activities
• Not warming up before exercising
• Having bowed legs
• Changes in activity levels
• Imbalance of the core muscles
• Injury to the area like a contusion or bruise

If you have ITB syndrome you may notice:

• Mild pain on the outside of your knee or hip when you begin to exercise, which goes away as you warm up.
• Over time, the pain feels worse and doesn't go away during exercise.
• Running down hills or sitting for a long time with your knee bent may make pain worse.

Your health care provider will examine your knee and move your leg in different positions to see if your ITB is tight. Usually, ITB syndrome can be diagnosed from the exam and your description of the symptoms.

If imaging tests are needed, they may include any of the following:

• Ultrasound
• MRI

If you have ITB syndrome, treatment may involve any of the following:

• Medicines or applying ice to relieve pain
• Stretching and strengthening exercises
• A shot of medicine called cortisone in the painful area to relieve pain and swelling

Most people do not need surgery. But if other treatments do not work, surgery may be recommended. During surgery, part of your ITB, the bursa, or both will be removed. Or, the ITB will be lengthened. This prevents the ITB from rubbing against the bone at the side of your knee.

At home, follow these measures to help reduce pain and swelling:

• Apply ice to the painful area for 15 minutes every 2 to 3 hours. Do not apply ice directly to your skin. Wrap the ice in a clean cloth first.
• Apply mild heat before stretching or doing strengthening exercises.
• Take pain medicine if you need to.

For pain, you can use ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn), or acetaminophen (Tylenol). You can buy these pain medicines at the store.

• Talk with your provider before using any pain medicines if you have heart disease, high blood pressure, kidney disease, or have had stomach ulcers or internal bleeding in the past.
• Do not take more than the amount recommended on the bottle or by your provider.

Try running or cycling shorter distances than you usually do. If you still have pain, avoid these activities completely. You may need to do other exercises that do not irritate your ITB, such as swimming.

Try wearing a knee sleeve to keep the bursa and ITB warm while you exercise.

Your provider may recommend a physical therapist (PT) to work with your specific injury so you can return to normal activity as soon as possible.

Your PT may recommend ways to change how you exercise to prevent problems. Exercises are aimed at strengthening your core and hip muscles. It will also focus on stretching your tissue to allow less irritation. You may also be fitted for arch supports (orthotics) to wear in your shoes.

Once you can do stretching and strengthening exercises without pain, you can gradually begin running or cycling again. Slowly build up distance and speed.

Your PT may give you exercises to do to help stretch your ITB and strengthen your leg muscles. Before and after activity:

• Use a heating pad on your knee to warm the area up. Make sure the pad's setting is on low or medium.
• Ice your knee and take pain medicine after activity if you feel pain.

The best way for the tendons to heal is to stick to a care plan. The more you rest and practice physical therapy, the quicker and better your injury will heal.

Call your provider if pain gets worse or does not get better in a few weeks.

IT band syndrome - aftercare; ITB syndrome - aftercare; Iliotibial band friction syndrome - aftercare

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Huntoon E, Dec KL, Caldwell M. Lower limb pain and dysfunction. In: Cifu DX, ed. Braddom's Physical Medicine & Rehabilitation. 6th ed. Philadelphia, PA: Elsevier; 2021:chap 36.

Riff AJ, Chalmers PN, Bach BR. Knee diagnosis and decision-making. In: Miller MD, Thompson SR, eds. DeLee, Drez, & Miller's Orthopaedic Sports Medicine: Principles and Practice. 5th ed. Philadelphia, PA: Elsevier; 2020:chap 90.

Updated by: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.