Iliotibial band syndrome

Iliotibial band syndrome, also called ITB syndrome or Iliotibial Band Syndrome (ITBS), is an overuse condition that causes pain on the outer side of the knee. It is one of the main causes of lateral knee pain in runners, but it also affects cyclists and athletes whose sports involve repeated knee flexion-extension movements. Its incidence is estimated at between 5 and 14% of running-related injuries.

The historical term “iliotibial band friction syndrome” is based on the idea that the band rubs repeatedly against the lateral femoral condyle. However, current biomechanical data suggest that the mechanism is probably more complex: the iliotibial band is a relatively stiff fibrous structure which, during repeated flexion-extension movements, would mainly increase the compression of the tissues lying between it and the lateral femoral condyle, particularly at around 20 to 30° of knee flexion.

The syndrome is therefore probably more a matter of mechanical and compressive overload of the lateral knee tissues than a simple friction phenomenon. It is generally linked to an increase in training load, combined with biomechanical and neuromuscular factors that can increase the stresses on the lateral compartment of the knee.

The iliotibial band is a longitudinal fibrous structure on the lateral side of the thigh. It is the thickened part of the fascia lata and receives fibres from the tensor fasciae latae and the gluteus maximus. It runs down the outer side of the thigh and inserts on the anterolateral part of the tibia, at Gerdy’s tubercle, contributing to the lateral stability of the hip and knee.

At the knee, it is closely related to the lateral femoral condyle, the lateral retinaculum, the joint capsule, the vastus lateralis, and the fatty and connective tissue structures beneath the band. This anatomy explains why a repeated increase in compression in this region can become painful.

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Biomechanics of the iliotibial band

The iliotibial band helps control the position of the lower limb in the frontal and transverse planes: it contributes to lateral knee stability, to the transmission of forces between the pelvis and the lower limb, to hip stabilisation and to limiting certain excessive movements of the lower limb.

During running, the knee passes several times per cycle through a range of flexion in which the stresses on the lateral tissues can be considerable. The repetition of thousands of cycles can become a problem when the load increases faster than the tissues’ capacity to adapt. However, the mechanism is not purely local: the biomechanics of the pelvis, hip, knee and foot all play a part in how the stresses are distributed.

The role of the hip and pelvis

Hip control plays an important role in running biomechanics. Reduced frontal-plane control of the pelvis or an increase in certain hip movements can alter the relative position of the knee and increase the stresses on the lateral structures. In some studies, runners with iliotibial band syndrome show differences in hip, knee and ankle kinematics compared with asymptomatic runners.

However, the findings in the literature remain heterogeneous: hip abductor weakness may be a contributing factor in some runners, but on its own it is not a universal explanation for the syndrome.

Iliotibial band syndrome is particularly common in distance runners. It accounts for a significant proportion of running-related injuries and is one of the most common causes of pain in the lateral compartment of the knee. It also affects cyclists, triathletes, hikers, endurance athletes and players of some team sports.

In runners, it frequently occurs during periods of increasing training load. Preparing for a half marathon, marathon or trail race can be a period of particular risk when volume or elevation gain increases rapidly.

Iliotibial band syndrome is multifactorial. It is generally linked to a combination of high mechanical load, insufficient recovery, biomechanical factors and insufficient muscle capacity of the pelvic chain.

Training load and terrain

The main trigger is often a recent increase in load: more mileage, more frequent sessions, a return after a break, higher speed, the introduction of interval training, a large increase in elevation gain, more descents or a sudden increase in the length of runs. Downhill running is particularly likely to increase the repeated stresses on the knee.

Terrain can also influence the stresses: prolonged running on a camber, on strongly cambered roads, on technical trails or downhill can alter lower limb kinematics. Repeated changes of direction can also increase lateral stresses.

Neuromuscular factors

Control of the pelvis and hip is an important part of the assessment: weakness of the hip abductors, deficits in the gluteus medius or gluteus maximus, reduced pelvic control, poor single-leg stability or insufficient knee control during running. Hip abductor strengthening is one of the most frequently studied management strategies: a systematic review published in 2024 found it to be a strategy common to the various studies, with improvements in pain and function over periods of 2 to 8 weeks. However, the syndrome should not be reduced to simple “gluteus medius weakness”.

Biomechanical factors

Biomechanical studies have found some differences between runners with and without iliotibial band syndrome in hip kinematics, lower limb rotation, knee movements and foot kinematics. One systematic review found differences in lower limb kinematics in runners with iliotibial band syndrome, but the results vary from study to study: there is therefore no single biomechanical profile of the affected runner, and the assessment must be individualised.

The main symptom is pain on the outer side of the knee, usually very well localised around the lateral femoral condyle. Runners often describe pain at a precise point, a burning sensation that is sometimes very sharp, appearing after a certain amount of time running.

A particularly characteristic feature is the predictable nature of symptom onset — for example, “the pain always starts after 25 minutes of running”. At first, the pain appears only during running and usually disappears quickly after stopping: the athlete may be completely symptom-free at rest, when walking and in daily life. As the condition progresses, the time before pain appears gradually shortens; in more severe forms, it can persist after the session and cause difficulty on stairs or with some daily activities.

Clinical examination

The diagnosis is mainly clinical. The examination looks for precise pain over the lateral femoral condyle, brought on by repeated knee flexion-extension, by running or by single-leg movements, as well as impaired pelvic control, weakness of the abductors or gluteus maximus and any abnormalities in running mechanics. Palpation of the lateral femoral condyle usually reproduces the pain precisely.

Two clinical tests are classically used: Noble’s test (pressure applied to the lateral part of the femoral condyle while the knee is gradually flexed, with reproduction of the pain being suggestive) and Ober’s test (looking for limited hip adduction with the lower limb extended). Its diagnostic value should, however, be interpreted with caution: a positive Ober’s test does not necessarily mean that the band is “too short” or that it needs to be stretched, as modern biomechanical data call into question the idea that simple stretching can significantly change its mechanical length.

Functional assessment completes the examination: the single-leg squat allows observation of pelvic stability, hip control, knee position and foot control; the step-down test (controlled stepping down from a step) looks at pelvic control, hip adduction and movement quality; running analysis can look at cadence, stride length, pelvic position, vertical oscillation and any asymmetries.

Surgery is rarely necessary. It may be discussed in chronic resistant forms after failure of properly conducted conservative management. Historical procedures include release of the band, resection of a pathological portion, bursectomy, or arthroscopic or open procedures depending on the situation.

The reported results are generally favourable in surgical series — one recent systematic review reported return-to-sport rates of 81 to 100% — but these data should be interpreted with caution because of the heterogeneity of the studies and the low level of evidence. Surgery should therefore only be considered after failure of properly conducted conservative treatment.

Recovery time depends mainly on how long the symptoms have been present, the sporting load, how quickly training is adjusted, muscle deficits, biomechanical factors and adherence to rehabilitation. Recent forms can often improve within a few weeks, whereas chronic forms may require several months.

In studies of conservative treatment, improvements in pain and function have been observed over periods ranging from 2 to 8 weeks, but the protocols remain very heterogeneous. A full return to the previous level of sport can take longer than the mere disappearance of pain.

Prevention is mainly based on good training load management: increasing mileage gradually, limiting sudden increases in elevation gain, introducing interval training gradually and varying terrain gradually.

Maintaining good hip abductor strength and good pelvic control, and avoiding sudden changes in shoes or running technique, also help limit the risk. In runners who have already had iliotibial band syndrome, regular strengthening of the pelvic chain can be built into the training programme.