Iliotibial band (IT band) syndrome is an overuse problem that is often seen in bicyclists, runners, and long-distance walkers. It causes pain on the outside of the knee just above the joint. It rarely gets so bad that it requires surgery, but it can be very bothersome. The discomfort may keep athletes and other active people from participating in the activities they enjoy.

Anatomy of IT band syndrome

The IT band is actually a long tendon. (Tendons connect muscles to bone.) It attaches to a short muscle at the top of the pelvis called the tensor fascia lata. The IT band runs down the side of the thigh and connects to the outside edge of the tibia (shinbone) just below the middle of the knee joint. You can feel the tendon on the outside of your thigh when you tighten your leg muscles. The IT band crosses over the side of the knee joint, giving added stability to the knee.

The lower end of the IT band passes over the outer edge of lateral femoral condyle, the area where the lower part of the femur (thighbone) bulges out above the knee joint. When the knee is bent and straightened, the tendon glides across the edge of the femoral condyle.

A bursa is a fluid-filled sac that cushions body tissues from friction. These sacs are present where

muscles or tendons glide against one another. A bursa rests between the femoral condyle and the IT band.

Normally, this bursa lets the tendon glide smoothly back and forth over the edge of the femoral condyle as the knee bends and straightens.

The IT band glides back and forth over the lateral femoral condyle as the knee bends and straightens. Normally, this isn’t a problem. But the bursa between the lateral femoral condyle and the IT band can become irritated and inflamed if the IT band starts to snap over the condyle with repeated knee motions such as those from walking, running, or biking. This leads to IT band syndrome.

People often end up with ilio tibial band syndrome from overdoing their activity. They try to push themselves too far, too fast, and they end up running, walking, or biking more than their body can handle. The repeated strain causes the bursa on the side of the knee to become inflamed.

Some experts believe that IT band syndrome happens when the knee bows outward. This can happen in runners if their shoes are worn on the outside edge, or if they run on slanted terrain. Others feel that certain foot abnormalities, such as foot pronation, causes ilito tibial band syndrome syndrome. (Pronation of the foot occurs when the arch flattens.)

Recently, health experts have found that runners with a weakened or fatigued gluteus medius muscle in the hip are more likely to end up with IT band syndrome. This muscle controls outward movements of the hip. If the gluteus medius isn’t doing its job, the thigh tends to turn inward. This makes the knee angle into a knock-kneed position. The IT band becomes tightened against the bursa on the side of the knee. This is also called a valgus deformity of the knee.

People with bowed legs may also be at risk of developing IT band syndrome. The outward angle of the bowed knee makes the lateral femoral condyle more prominent and can make the snapping worse. This condition is also called a varus deformity of the knee.

The symptoms of IT band syndrome commonly begin with pain over the outside of the knee, just above the knee joint. Tenderness in this area is usually worse after activity. As the bursitis grows worse, pain may radiate up the side of the thigh and down the side of the leg. Patients sometimes report a snapping or popping sensation on the outside of the knee.