Iliotibial band syndrome

Iliotibial band (friction) syndrome is a common cause of lateral knee pain related to intense physical activity resulting in chronic inflammation of the fat adjacent to the iliotibial band (ITB). Alternatively, the same pathology can occur over the greater trochanter and is considered the same diagnosis.

Epidemiology

Iliotibial band syndrome commonly affects young patients who are physically active, most often long-distance runners or cyclists. The exact prevalence is unknown, but one study has found the prevalence among actively-training marines to be higher than 20% ⁵.  Iliotibial band syndrome accounts for 12% of running-related overuse injuries ⁴.

Associations

The following physical factors are reported to be associated with the development of iliotibial band syndrome ⁴:

• limb length discrepancy
• genu varum
• overpronation
• hip adductor weakness
• myofascial restriction

Clinical presentation

Classically, iliotibial band syndrome is diagnosed by history and physical examination. Pain over the greater trochanter or at the lateral knee joint is the presenting symptom with point tenderness 1-2 cm above the lateral joint line. Pain is usually worse with downhill running and increases throughout an episode of activity ⁴.

Pathology

When the knee flexes, the iliotibial band moves posteriorly over the lateral femoral epicondyle. When the band is excessively tight or stressed, the iliotibial band rubs against the epicondyle irritating the lateral synovial recess. 

With hip flexion, the iliotibial band slides anteriorly over the greater trochanter and may cause a painful clunking sensation or audible snap.

Microscopic appearance

In iliotibial band syndrome, histologic analysis demonstrates inflammation and hyperplasia in the synovium. 

Radiographic features

Ultrasound

Allows visualisation of the impingement by assessing dynamic motion of the iliotibial band through knee flexion and extension.

MRI

MRI is reserved for when the diagnosis is unclear and to exclude other aetiologies of lateral knee pain such as a meniscal tear or lateral collateral ligament injury.

MR findings of iliotibial band syndrome include ill-defined signal abnormality within the fatty soft tissues interposed between the iliotibial band and bone. In the knee, the soft tissues lateral to the lateral femoral condyle show low T1 and high on T2 signal, in keeping with oedema/fluid. In the hip, similar soft tissue changes are present and there may also be tendinopathy or tear of the gluteus medius or minimus tendons. There may also be marrow oedema in the affected bone.

Cystic areas representing primary or secondary (adventitious) bursae may be identified.

Chronic MR findings include thickening of the iliotibial band and increased T2 signal intensity superficial to the ITBiliotibial band are occasionally seen. Soft tissue fibrosis and bony proliferation may be present.

Treatment and prognosis

Initial treatment of iliotibial band syndrome is conservative, consisting of physical therapy, anti-inflammatory medication, and steroid injections ³.

Surgical treatment is reserved only for those who fail conservative treatment and includes resection of the posterior aspect of the iliotibial band ³.

Differential diagnosis

General imaging differential considerations of lateral knee pain include:

• lateral meniscal tear
• lateral collateral ligament injury

See also

• proximal iliotibial band syndrome