Iliotibial Band Friction Syndrome 

Iliotibial band friction syndrome (ITBFS) is a common cause of lateral knee pain, particularly among runners, military personnel, and cyclists.^{[1, 2]} It is considered an overuse syndrome that usually is treated successfully with a conservative approach. Biomechanical and training factors play a large role in the development of ITBFS, but its exact etiology is somewhat elusive.^{[3, 4]}

Conservative therapy is successful in most persons with ITBFS. When conservative therapy does not resolve the pain, surgery may be indicated. Conservative therapy should be employed for 3 months before surgery, but most patients for whom surgery is necessary have had symptoms for more than 9 months.

Surgery is rarely indicated, but the most common procedure for ITBFS is resection of the posterior portion of the iliotibial band (ITB) and, if desired, the adventitial bursa deep to the band. Surgery is performed with the knee held in 30° of flexion and consists of a limited resection of a small triangular or elliptical piece of the posterior part of the ITB covering the lateral femoral epicondyle. The bursa may be removed in certain cases as well.

Iliotibial band friction syndrome (ITBFS) typically is observed in people who exercise vigorously. The overuse creates stress that the body cannot repair, and soft tissue breakdown occurs.^[5] When the knee flexes, the ITB moves posteriorly along the lateral femoral epicondyle. Contact against the condyle is highest between 20° and 30° (average 21°), so when the band is excessively tight or stressed, the ITB rubs more vigorously. The space deep to the ITB is believed to have an adventitial bursal extension from the synovial capsule. This space was coined the lateral synovial recess (LSR). The LSR lies underneath the ITB and acts as an interface between the ITB and the lateral femoral epicondyle, as in the image below.

In runners, friction occurs near or just after foot strike during the contact phase of the gait cycle. Downhill running reduces the knee flexion angle and can aggravate ITBFS, while sprinting and fast running increase the knee flexion angle and are less likely to cause the syndrome.^{[2, 6, 7, 8, 9]} The friction point at the lateral epicondyle prominence is illustrated in the image below.

Frequency

Overall incidence of iliotibial band friction syndrome (ITBFS) in the general population is not well reported. Depending on which population is examined, the incidence ranges from 1.6-52%. Incidence varies with the target population's type and intensity of activity. For instance, Linenger et al reported that in 12 weeks of Marine basic training, ITBFS was the most common specific injury and accounted for 22.2% of all lower extremity injuries. Runners experience 12% of all running-related overuse injuries from ITBFS.^[10]

The etiology of iliotibial band friction syndrome (ITBFS) is multifactorial. Many factors have been postulated, few with overwhelming evidence supporting them.

ITBFS usually is caused by overuse, mostly due to errors in training. Single session errors cause ITBFS as often as repetitive deficiencies. Sudden changes in surface (ie, soft to hard, flat to uneven or decline), speed, distance, shoes, and frequency can break down the body faster than it can heal, causing injury. Other factors frequently reported are the following:

• Limb length discrepancy
• Genu varum
• Overpronation
• Hip adductor weakness
• Myofascial restriction

Studies examining limb length discrepancies provide conflicting conclusions regarding whether a direct correlation exists. Limb length inequalities cause changes in hip abduction during the gait cycle, sacral leveling, and pelvic tilt, which is believed to increase tension on the ITB and tensor fascia lata. However, other studies did not find a direct correlation between limb length inequality and ITBFS. Still, the postulate merits consideration when examining the hip and pelvis.^{[11, 12]}

Genu varum is considered a risk factor because of increased tension on the ITB as it is stretched more over the lateral femoral epicondyle. This concept is widely accepted, though with little empirical support.

Overpronation is controversial as well. In the running cycle, the lower limb strikes the ground with a rigid supinated foot. As the leg moves forward, the tibia internally rotates over the planted foot, "unlocking" it into a pronated-everted position, which allows for weightbearing. Pronation and internal rotation stress the ITB. Excessive pronation causes quicker tibial internal rotation and increased hip adduction, stressing the ITB over the lateral femoral condyle.

James implicated a combination of genu varum, heel varus, forefoot supination, and compensatory pronation with ITBFS, but further videography studies led to dispute of that claim. Most studies support overpronation as a potential cause.^[7]

Hip abductor weakness is an important factor as well. Several studies support this claim. When the foot strikes the ground, the femur adducts against the eccentric load of the abductors (gluteus medius and tensor fascia lata). These muscles move from eccentric to concentric through the support phase and into the propulsive phase of gait. The gluteus medius also externally rotates the hip, while the tensor fascia lata internally rotates.

When the hip abductors are weakened or fatigued, runners have increased adduction and internal rotation at midstance. This generates more valgus force at the knee, which Fredericson postulates as increasing tension and friction on the ITB.^{[13, 14]}

Myofascial restrictions and inflexibility can increase stress in the posterior ITB, particularly with the tensor fascia lata. Tightness in the hip flexors (iliopsoas), extensors (gluteal muscles), and rotators (particularly piriformis) can shift more load to the abductors and adductors. Weaker hip abductors eventually fail under continuous stress.

A small recess is formed between the lateral femoral epicondyle and the ITB as it travels along the lateral thigh to the tibial plateau. This space was believed to have a separate bursa lying deep to the band, but studies have revealed it to be synovium that is a lateral extension and invagination of the actual knee joint capsule (lateral synovial recess). Histologic analysis demonstrates inflammation and hyperplasia in the synovium, while MRI studies have demonstrated diffuse signal abnormality below the band and in the synovium but not in the ITB. This suggests that this syndrome is not a tendinopathy. Variance is observed in the congenital thickness of the band, so patients with thicker bands may be predisposed to ITBFS.

While pain is localized along the lateral knee, it also can include the hip, as in the image below. Pain is worse with downhill running and becomes worse with activity after a pain-free start. Pain may radiate from knee proximally or distally. Most individuals experience pain only during activities; however, individuals may experience pain with walking as the syndrome progresses.

Tenderness is over the lateral knee, with a tender point at the lateral femoral condyle, approximately 1-2 cm proximal to the lateral joint line. Pain can be elicited with active flexion-extension of the knee within the first 30° while the thumb presses over the epicondyle and ITB. Crepitation may be felt.

Restriction in hip adduction indicates tightness in the ITB and tensor fascia lata. In evaluating for iliotibial band friction syndrome (ITBFS), also look for restrictions in iliopsoas, rectus femoris, gastrocnemius, and soleus function. Examination usually reveals restriction of hip adduction and weakness of the hip abductors, specifically the gluteus medius.

Myofascial restrictions can mimic ITBFS, and these restrictions can be identified with a careful examination. Trigger points along the vastus lateralis, biceps femoris, and gluteus minimus can refer pain to the lateral knee, while fascial adhesions of the posterior ITB can generate pain as well. Careful palpation of these points can differentiate ITBFS from myofascial trigger points.

The following provocative tests may be helpful:

• Ober test: This test is performed with patient lying on the unaffected side with that hip flexed enough to straighten the lumbar lordosis. The down leg is flexed 90° at the knee, while the operator's hands stabilize the greater trochanter and hold up the ankle. The thigh is abducted passively and extended to catch the ITB over the greater trochanter. The thigh is then adducted passively. If the thigh remains suspended off the table, this indicates a shortened ITB, as in the image below. Iliotibial band noted prominently along the lateral thigh.
• Noble test: Place the patient supine with the knee at approximately 90° flexion and apply firm digital pressure on or around the lateral femoral epicondyle while passively extending the knee. A positive result is pain elicited at approximately 30° of flexion over the lateral femoral epicondyle, similar to what occurs when the patient is active.
• Renee creak test: Place patients on a step stool and have them support all of their weight on the affected leg. The operator's thumb is placed over the lateral femoral condyle and pressure is applied while the patient bends the knee into 30-40° of flexion. Here, the posterior fibers of the ITB are directly over the lateral epicondyle, as in the image below; reproduction of pain with pressure is considered a positive test result for ITBFS. Some literature lists separately the creak test. This is the same as the Renee test, but the operator thumb is not placed on the patient. Pain when the patient bends the knee 30° is considered a positive test result. Iliotibial band at the lateral femoral epicondyle, with the posterior fibers denoted.
• Thomas test: The patient sits on the end of the table and then rolls back into a supine position, holding both knees to the chest but not so that the pelvis has excessive posterior tilt. This flattens the lumbar spine. The patient holds the leg of the asymptomatic hip and slowly lowers the other to the floor. The Thomas test result is considered positive if the patient cannot achieve 90° of knee flexion, a neutral angle of the hip (if the hip hovers above the table), or 15° of hip abduction relative to the pelvis. This test is used to evaluate the iliopsoas, rectus femoris, and tensor fascia lata and/or ITB, as in the image below. The Thomas test can be used to evaluate restriction in the iliotibial band, hip flexors, and rectus femoris.

Failure of conservative therapy is an indication for surgery. Conservative therapy includes rest, stretching and strengthening exercises, anti-inflammatory medication, other therapy modalities, and biomechanical correction of limb length discrepancies and pes planus. A minimum trial of 3 months should be given before considering surgery. Even then, surgery is best withheld for highly motivated people who want to return to their sport or activity.

The iliotibial band (ITB) originates from the outer lip of the anterior iliac crest, anterior border of the ilium, and outer surface of anterior superior iliac spine. The tensor fascia lata originates here also, and its fascia blends with the ITB at the lateroanterior thigh one third of the way distally. The intermuscular septum connects the ITB to the linea aspera femoris until inserting just proximal to the lateral femoral condyle.

From there, it passes in its broad expansion between lateral aspect of patella and biceps femoris to insert into the Gerdy tubercle, off the lateral tibial plateau. This expanse helps the lateral collateral ligament and posterolateral capsule to stabilize the knee.

The primary synergistic muscles are the hip abductors. These muscles are the gluteus medius, gluteus minimus, and upper fibers of the gluteus maximus. Their nerve supply comes from the superior gluteal nerve, which is a branch off of the L4, L5, and S1 nerve roots.^[15]

Active infection and coagulopathy are contraindications to surgery.