”Runner’s knee”, scientifically known as iliotibial bundle friction syndrome, also known as lateral knee pain syndrome, iliotibial bundle syndrome, is a condition caused by injury or strain to the iliotibial bundle due to repetitive knee flexion and extension activities. It is a bursitis or tendonitis caused by friction between the posterior aspect of the iliotibial bundle and the lateral epicondyle of the femur during knee flexion. It is also known as “runner’s knee” because it occurs in long-distance runners and cyclists who ride long distances.
The iliotibial bundle is a connective tissue tendon that extends from the hip and covers the lateral surface of the knee joint to the lateral surface of the tibia, above which muscles such as the gluteus maximus and vastus medialis are attached. Its function is to prevent internal rotation of the tibia, to straighten the knee joint and to abduct the hip joint.
The iliotibial bundle can be felt on the outside of the thigh when the thigh muscles are tightened with force. There is a bursa between the iliotibial bundle and the lateral epicondyle of the femur (the lateral projection of the knee), which is used to lubricate the gliding of the iliotibial bundle and reduce friction with the femur.
Iliotibial bundle abrasion syndrome is often seen in cyclists, long-distance runners and race walkers and is primarily caused by excessive friction between the iliotibial bundle and the lateral epicondyle of the femur, resulting in inflammation of the ligament or bursa. The main symptoms are swelling and pain. Because the iliotibial bundle passes through the femur, it is susceptible to contact with the lateral epicondyle of the femur. When the knee is extended and flexed, the iliotibial bundle slips outside the upper femoral ankle, with the greatest friction on the iliotibial bundle occurring at approximately 20-30 degrees of flexion. Excessive friction can lead to inflammation, which prevents the iliotibial bundle from sliding and causes pain during activity.
1, iliotibial bundle friction syndrome is mainly due to poor training habits and/or anatomical abnormalities and some other factors that together cause excessive pressure on the iliotibial bundle.
2, Inadequate warm-up and finishing exercises.
3, Overly rapid increase in training distance and duration.
4, anatomical abnormalities, such as “o-shaped” legs, flat feet, heel or foot inversion, bilateral lower limb unequal length, internal rotation of the tibia, overdeveloped thigh muscles or too tight iliotibial bundle, etc.
5. Excessive exercise shortens the iliotibial bundle.
6.Weak adductor muscles such as gluteus medius.
For long-distance runners.
Long-distance runners have a higher incidence of iliotibial bundle abrasion syndrome than sprinters, probably because long-distance runners have a more pronounced and prolonged foot-following period and upright period. When the foot is on the ground, the knee is usually flexed approximately 20 degrees, which makes the iliotibial bundle most susceptible to abrasion with the external superior femoral ankle. Running on stacked, protruding or bucket-sloping surfaces, such as sand dunes, causes the leg to bend slightly inward, causing the iliotibial bundle to hyperextend and press against the femur. Also, wearing running shoes with excessive wear on the outside of the heel can be a cause.
For cyclists.
The main cause is increased friction caused by continuous high frequency pedaling and inversion of the knee in high position. Also, improper bike fit such as too high a seat, incorrect frame angle, and pedals placed too far in or rotated inward can increase pressure on the iliotibial bundle.
The typical symptom is localized pain at the outermost prominence of the knee joint during activity, in a well-defined location, which is relieved after rest. Some athletes can present with widespread pain on the lateral side of the knee because of the severity of the inflammation, which can even occur at rest.
Symptoms of iliotibial tract abrasion syndrome include
Pain in or around the lateral superior femoral ankle, predominantly tingling. Pain that increases during running, especially when going downhill. This is because the quadriceps (anterior thigh muscles) are in a state of centrifugal contraction during downhill running, increasing the muscle load and the tension placed on the fascia near the knee joint. The pain is most pronounced when the knee joint is flexed 20-30 degrees or straightened. The strength of the hip joint is reduced during abduction. In severe inflammation of the bursa, the pain may even radiate to the lateral aspect of the thigh and calf and may occur with a popping sound.
Physical examination of iliotibial tract abrasion syndrome.
A detailed history is taken, followed by a physical examination to analyze the location of pressure pain, swelling, tension of the iliotibial bundle, and the anatomy of the lower extremity, usually with an Ober’s test. Imaging tests such as X-rays and magnetic resonance imaging are performed when necessary.
The chronic inflammatory stage is the stage when the pain is stable and persistent. It is best to control the pain and eliminate the inflammation as soon as possible through physical therapy such as medium frequency electricity, ultrasound and short wave. After this stage, the pain can be controlled by physiotherapy such as MF, ultrasound and short wave. Iliotibial bands can be used to help reduce the pressure on the rubbing area during exercise. The main purpose is to improve the flexibility of the hip abductor muscles and the iliotibial band, thus reducing the pressure on the iliotibial band and reducing the friction between the iliotibial band and the lateral femoral condyle.
The following are some of the rehabilitative exercises that can be prevented or to be performed after an injury occurs.
1.Standing position iliotibial band extension
2.Lateral leaning iliotibial extension
Have the healthy leg cross in front of the affected leg, bend the body down and try to touch the toes of the affected leg. Hold for 30 seconds, return to the original position and repeat 3 times.
3.Stand sideways against the wall with the affected leg on the inside. Hands on the wall for support. Cross the leg on the healthy side in front of the injured leg, keeping the foot of the injured lower limb stable. Make the hip lean against the wall. Hold for 30 seconds, return to the original position and repeat 3 times.
4, quadriceps extension
The hand on the healthy side holds a more fixed object or stands by the wall for support, the affected hand grasps the ankle of the affected lower limb and pulls it toward the hip, do not bend or twist the waist and back. Hold for 30 seconds, return to the original position and repeat 3 times.
5.Hip inversion training (lateral recumbent position)
Lie on the affected side, flex the knee on the healthy side and put the foot flat in front of the affected limb while the affected limb is straightened, lift the affected limb as high as possible without discomfort, hold it in the highest position for 6-10 seconds, then slowly lower the affected limb back to the original position and repeat 20-30 times.
6.Hand X treatment
Iliotibial tract abrasion syndrome usually does not require surgical treatment, but when various conservative treatments are ineffective, surgical treatment needs to be considered. Hand X includes bursa removal, release or lengthening of the iliotibial bundle to reduce its friction on the femur. Postoperative rehabilitation continues.