Iliotibial Band Syndrome

Pain at the outside of the knee could be a symptom of iliotibial (IT) band syndrome. Pain starts when there is too much tension in the IT band, a wide strip of soft tissue that runs down the outer thigh and ends just below the knee. 

Runners, cyclists, and other athletes whose sports require repetitive movements are most likely to develop this condition.

Exactly how the IT band causes knee pain is not well understood. Experts have proposed possible types of iliotibial band syndrome with different explanation. 

Iliotibial Band Friction Syndrome

When the knee bends about 30 degrees,¹Pegrum J, Self A, Hall N. Iliotibial band syndrome. BMJ. 2019;364:l980. doi:10.1136/bmj.l980^,2Fairclough J, Hayashi K, Toumi H, et al. The functional anatomy of the iliotibial band during flexion and extension of the knee: implications for understanding iliotibial band syndrome. J Anat. 2006;208(3):309-316. doi:10.1111/j.1469-7580.2006.00531.x the bottom of the IT band slides over the outside of the knee joint. It passes over the knobby end of the femur (thigh bone), called the femoral epicondyle. 

See Guide to Knee Joint Anatomy

If the IT band is tight, it will rub against this area rather than glide over it. Over time, the friction causes the IT band to become inflamed and painful.³Mellinger S, Neurohr GA. Evidence based treatment options for common knee injuries in runners. Ann Transl Med. 2019;7(Suppl 7):S249. doi:10.21037/atm.2019.04.08^,4Walbron P, Jacquot A, Geoffroy JM, Sirveaux F, Molé D. Iliotibial band friction syndrome: An original technique of digastric release of the iliotibial band from Gerdy’s tubercle. Orthopaedics & Traumatology: Surgery & Research. 2018;104(8):1209-1213. doi: 10.1016/j.otsr.2018.08.013

Friction is the most widely accepted explanation for how the IT band causes knee pain.³Mellinger S, Neurohr GA. Evidence based treatment options for common knee injuries in runners. Ann Transl Med. 2019;7(Suppl 7):S249. doi:10.21037/atm.2019.04.08^,4Walbron P, Jacquot A, Geoffroy JM, Sirveaux F, Molé D. Iliotibial band friction syndrome: An original technique of digastric release of the iliotibial band from Gerdy’s tubercle. Orthopaedics & Traumatology: Surgery & Research. 2018;104(8):1209-1213. doi: 10.1016/j.otsr.2018.08.013

Iliotibial Band Compression Syndrome

Not all experts believe the IT band slides over the femur when the knee bends. Iliotibial band compression syndrome suggests the IT band is anchored in place and squeezes soft tissues when the knee is bent about 30 degrees. Repeated squeezing of these tissues causes leads to irritation and pain.³Mellinger S, Neurohr GA. Evidence based treatment options for common knee injuries in runners. Ann Transl Med. 2019;7(Suppl 7):S249. doi:10.21037/atm.2019.04.08

Iliotibial band compression syndrome suggests the soft tissues, including fat deposits, nerves, and blood vessels—not the IT band itself—are the source of pain.³Mellinger S, Neurohr GA. Evidence based treatment options for common knee injuries in runners. Ann Transl Med. 2019;7(Suppl 7):S249. doi:10.21037/atm.2019.04.08

Iliotibial Band Enthesopathy

A less commonly discussed cause of IT band related knee pain is called enthesopathy.⁴Walbron P, Jacquot A, Geoffroy JM, Sirveaux F, Molé D. Iliotibial band friction syndrome: An original technique of digastric release of the iliotibial band from Gerdy’s tubercle. Orthopaedics & Traumatology: Surgery & Research. 2018;104(8):1209-1213. doi: 10.1016/j.otsr.2018.08.013^,5Hegde G, Subramanian A, Azzopardi C, Patel A, James SL, Botchu R. Iliotibial band enthesopathy: an unusual cause of lateral knee pain post total knee replacement. J Ultrasound. 2021;25(1):83-87. doi:10.1007/s40477-021-00565-z The IT band becomes inflamed, injured, or damaged at a point where it attaches to bone. 

• The IT band has several points of attachment, called entheses.
• One entheses is located near the top of the outer tibia.
• Enthesopathy at this point would cause pain in the outer knee.
• Pain from this condition may be felt a little lower on the outer knee than pain caused by iliotibial band friction or compression.

No matter how IT band syndrome causes pain, doctors generally agree on its symptoms and how to diagnose it. Most people heal without needing surgery.

IT Band Anatomy

Unlike many other parts of the body that get injured, the IT band is not a distinct piece of anatomy. Learning about its structure and how it works can help with understanding IT band syndrome symptoms, diagnosis, and treatment. 

What is the IT band?

Sometimes called Maissiat band⁶Hyland S, Graefe SB, Varacallo M. Anatomy, Bony Pelvis and Lower Limb, Iliotibial Band (Tract). In: StatPearls. StatPearls Publishing; 2023. Accessed September 21, 2023 http://www.ncbi.nlm.nih.gov/books/NBK537097/    or iliotibial tract,⁷Iliotibial tract | Stedman’s Online | Wolters Kluwer. Accessed September 18, 2023. https://stedmansonline.com/lww/term/mlrI1200000935/649775/iliotibial-tract  the IT band runs from the outer hip to the knee.  It is made of fascia, a tough, flexible tissue that surrounds muscles and organs throughout the body. 

The top of the IT band is formed where the fascia connected to 3 hip muscles blends together. Those hip muscles include the:

• Tensor fascia latae
• Gluteus maximus
• Gluteus medius muscles

The IT band is part of a larger layer of fascia that surrounds muscles in the thigh. The fascia of the IT band is thicker and stronger than the rest of this layer. 

• The fascia that surrounds muscles is typically less than 1 mm thick.⁸Wilke J, Macchi V, De Caro R, Stecco C. Fascia thickness, aging and flexibility: is there an association? J Anat. 2019;234(1):43-49.  doi:10.1111/joa.12902
• Near the knee joint, the fascia of the IT band is 1 mm to 4 mm thick⁵Hegde G, Subramanian A, Azzopardi C, Patel A, James SL, Botchu R. Iliotibial band enthesopathy: an unusual cause of lateral knee pain post total knee replacement. J Ultrasound. 2021;25(1):83-87. doi:10.1007/s40477-021-00565-z^,9Agridag Ucpinar B, Bankaoglu M, Eren OT, Erturk SM. Measurement of iliotibial band diameter in iliotibial band friction syndrome and comparison with an asymptomatic population. Acta Radiol. 2021;62(9):1188-1192. doi:10.1177/0284185120958407 and about 4 cm wide.¹⁰Orchard JW, Fricker PA, Abud AT, Mason BR. Biomechanics of iliotibial band friction syndrome in runners. Am J Sports Med. 1996;24(3):375-379. doi:10.1177/036354659602400321   

About 1½ ft (44 cm)¹⁰Orchard JW, Fricker PA, Abud AT, Mason BR. Biomechanics of iliotibial band friction syndrome in runners. Am J Sports Med. 1996;24(3):375-379. doi:10.1177/036354659602400321 long, the IT band attaches to several bones. 

• The top of the IT band attaches to an area of the pelvic bone called the iliac crest. 
• It travels down, over the outer hip and down the thigh, where it attaches to different points on the femur. 
• It then passes the outer knee joint, where the femur and tibia meet, and connects with the kneecap.²Fairclough J, Hayashi K, Toumi H, et al. The functional anatomy of the iliotibial band during flexion and extension of the knee: implications for understanding iliotibial band syndrome. J Anat. 2006;208(3):309-316. doi:10.1111/j.1469-7580.2006.00531.x^,11Hutchinson LA, Lichtwark GA, Willy RW, Kelly LA. The Iliotibial Band: A Complex Structure with Versatile Functions. Sports Med. 2022;52(5):995-1008. doi:10.1007/s40279-021-01634-3
• The bottom of the IT band attaches to an area at the top of the tibia called Gerdy tubercle, near the front and outside of the knee. 

Fascia is found throughout the body. The fascial membrane that surrounds and separates muscles and groups of muscles is called muscle fascia, deep fascia, or visceral fasci viscera.¹²Subcutaneous tissue | Stedman’s Online | Wolters Kluwer. Accessed September 18, 2023. https://stedmansonline.com/lww/term/mlrS2100001249/610688/subcutaneous-tissue 

What does the IT band do?

Knee and hip joint stability rely on the IT band. A tight, injured, or inflamed IT band can affect joint strength and alignment. 

The IT band also serves as a tendon, connecting the gluteus maximus and tensor fasciae latae muscles to the pelvis.¹¹Hutchinson LA, Lichtwark GA, Willy RW, Kelly LA. The Iliotibial Band: A Complex Structure with Versatile Functions. Sports Med. 2022;52(5):995-1008. doi:10.1007/s40279-021-01634-3 It supports certain movements, such as raising the leg at the hip (hip flexion) and rotating the thigh inward and outward (internal and external hip rotation).

Is the IT band a tendon or a ligament?¹³Geisler PR. Current Clinical Concepts: Synthesizing the Available Evidence for Improved Clinical Outcomes in Iliotibial Band Impingement Syndrome. Journal of Athletic Training. 2020;56(8):805-815. doi:10.4085/1062-6050-548-19

Tendons, ligaments, normal muscle fascia, and the IT band are all made of the same type of fiber-dense tissue. The IT band connects muscle to bone, like tendons. It also connects bone to bone, like ligaments. However, the IT band is usually described as an area of thick or reinforced muscle fascia.⁷Iliotibial tract | Stedman’s Online | Wolters Kluwer. Accessed September 18, 2023. https://stedmansonline.com/lww/term/mlrI1200000935/649775/iliotibial-tract 

To prevent confusion, use the terms iliotibial band and IT band and avoid other labels. 

A Common Cause of Knee Pain

Researchers who looked at the results of 42 research studies reported that nearly 8% of runners have symptoms of IT band syndrome.¹⁴Kakouris N, Yener N, Fong DTP. A systematic review of running-related musculoskeletal injuries in runners. J Sport Health Sci. 2021;10(5):513-522. doi:10.1016/j.jshs.2021.04.001 It is one of the most common causes of knee pain among athletes and other active people.   

Is IT band syndrome serious?

Without rest and treatment, IT band syndrome can get worse and pain will become more frequent and severe. Over time, damage to the IT band can lead to other problems, such as patellofemoral pain syndrome.¹⁵Hadeed A, Tapscott D. Iliotibial Band Friction Syndrome. StatPearls Publishing; 2022. Accessed September 21, 2023. https://europepmc.org/article/NBK/nbk542185 

Most people who get IT band syndrome recover with rest and treatment. Finding a treatment or combination of treatments that work requires getting an accurate diagnosis first.

The IT Band and Hip Pain

It is possible for the IT band to cause hip pain instead of—or in addition to—knee pain. The formal medical name for this condition is proximal iliotibial band syndrome. It is linked to greater trochanteric pain syndrome, an umbrella term for many conditions that cause tenderness and pain at the outside of the hip. 

In addition to IT band syndrome, greater trochanteric pain syndrome can be caused by hip bursitis, external snapping hip syndrome, and injury to tendon tissue that connects the gluteus medius muscle to the pelvis.¹⁶Chamberlain R. Hip Pain in Adults: Evaluation and Differential Diagnosis. Am Fam Physician. 2021;1 103(2):81-89.