IT band syndrome

What is IT band syndrome?

Iliotibial band syndrome (ITBS) is an overuse injury that causes pain on the outer side of the knee and the lower thigh¹. The iliotibial band is a thick strip of fibrous tissue that runs down the outside of your leg². You may also see it called ITB syndrome or IT band friction syndrome.

It's one of the most common running injuries³. Most of what's known comes from adult runners, so the figures shouldn't be applied to children, people who don't run, or the general population.

What causes it, and who gets it?

The cause isn't fully settled. Older theories blamed the band rubbing over the bony bump on the outer thigh bone at the knee (the lateral femoral epicondyle). More recent thinking is that the band is pinched or compressed against that bump when the knee is slightly bent³⁴.

Several things probably combine. These include how your joints move, and training and equipment factors such as a sudden rise in running distance, hill running and unsuitable footwear⁴. Links between weekly distance, intensity or recent training changes and running injuries in general are mixed, so no particular amount of running is known to bring ITBS on⁵. Small differences in how the hip and knee move have been seen in female runners with ITBS, but they are small and not yet clear enough to guide advice³.

Runners are most at risk, and women runners are about twice as likely as men to be affected⁶. The pain can also come on during cycling¹.

What does it feel like, and what can make knee pain serious?

ITBS usually causes a sharp or burning pain on the outer side of the knee when the knee is slightly bent, and it increases during running⁴. It comes on gradually during long activity such as running or cycling¹. It tends to worsen with continued movement and settle with rest, and some people notice swelling at the sore spot².

Diagnosis is mainly made from your story and a physical examination. Imaging is kept for pain that persists or for ruling out other problems⁷¹. Single knee tests rarely settle the diagnosis on their own⁸, and knee pain has many possible causes, so it isn't something to self-diagnose⁹.

Outer knee pain can also come from a tear in the cartilage cushion at the outer knee (the lateral meniscus), ligament problems, cartilage damage, swelling within the bone, a tendon problem at the back of the outer knee (biceps femoris tendinopathy), or pain referred from elsewhere¹⁰. Ligament injuries and sudden meniscus injuries are other possibilities after a fall, twist or high-impact injury, and pain after those shouldn't be assumed to be ITBS¹¹.

Some features point away from ITBS:

• A hot, red, swollen, painful knee with fever or feeling unwell can mean an infection in the joint (septic arthritis), which is an emergency¹¹.
• A knee that has slipped out of place, changed shape or points at an odd angle, or tingling or numbness in the knee, leg or toes¹².
• Locking, giving way or painful clicking can point to an internal knee injury such as a meniscus tear. Painless clicking is normal⁹¹².
• Severe pain, marked swelling or being unable to move or put weight on the knee, especially after a sudden injury¹³¹⁴¹⁵.
• Night pain, or constant severe pain that's worse on weight bearing with little or no injury, can be a sign of a bone problem called spontaneous osteonecrosis of the knee. Night pain most commonly affects women over 55¹¹.

What helps first?

Treatment starts without surgery⁷. Self-care and exercise come first. Early care usually means easing back from the activity that sets the pain off, changing equipment where that applies, and sometimes anti-inflammatory tablets, with physiotherapy alongside¹⁶¹⁷. A physiotherapist can guide stretches and correction of muscle imbalances¹⁶. Active rehabilitation that builds strength and manages how much load you put through the leg is suggested as the first approach for a new diagnosis¹⁰.

Strengthening the hip abductors (the muscles at the side of the hip that lift your leg outwards) is the best-supported single part of rehabilitation. It can reduce pain and improve function in runners with ITBS, especially alongside shockwave or manual therapy⁴. The evidence overall is weak: most studies are small, short and low quality, so firm recommendations aren't yet possible³. Once the sharp pain has settled, the aim is to build flexibility and strength in both the hip and the knee².

Exercises shouldn't cause pain, and they're not suited to anyone who already has a knee injury¹⁸.

What if that isn't enough?

There isn't much good evidence on what works when first-line care doesn't settle things. Pain that is getting worse, or hasn't improved after three to four weeks of self-help, can be a sign the cause isn't ITBS and the diagnosis needs another look¹⁹.

Gait retraining (coaching to change how you run) looked promising in one small study, but better trials are needed⁴. Hip strengthening combined with shockwave or manual therapy has also been reported to help⁴.

Surgery is kept for persistent or chronic cases that haven't responded to conservative care⁷²⁰. A keyhole (arthroscopic) operation has been described for these cases¹⁷. How well surgery works compared with other care isn't clear yet.

How long does it take to get better, and can it come back?

There's no clear timeline for ITBS. With conservative care, pain and function in runners with ITBS tend to improve over 2–8 weeks⁴. Among recreational runners with knee injuries in general (not ITBS alone), about one-third hadn't recovered at follow-up²¹.

How often ITBS returns, and what stops it coming back, isn't clear yet. The one step suggested for recovery is building flexibility and strength in the hip and knee once the acute symptoms have settled². Returning to activity gradually, rather than all at once, is a sensible way to go about it.