Patellofemoral syndrome (Runners knee)

What is Patellofemoral syndrome (Runners knee)

Runners knee is more correctly called patellofemoral syndrome. It presents as anterior knee pain, generally worsened by stairs and caused by dynamic valgus rather than any structural pathology of the cartilage.

It is common in runners and more often found in women than men. Pain is caused by compression of nerve fibers in the retinaculum or in the subchondral bone of the patella or from a synovitis.

The Clinical Syndrome

Runner’s knee is a relatively uncommon cause of lateral knee pain encountered in clinical practice. Also known as iliotibial band friction syndrome, runner’s knee is an overuse syndrome caused by friction injury to the iliotibial band as it rubs back and forth across the lateral epicondyle of the femur during running.

Runners knee is a clinical entity distinct from iliotibial bursitis, although these two painful conditions frequently coexist. This painful condition occurs more commonly in patients with genu varum and planus feet, although worn-out jogging shoes also have been implicated in the evolution of this disease.

What are the Symptoms of Patellofemoral syndrome

Physical examination may reveal point tenderness over the lateral epicondyle of the femur just above the tendinous insertion of the iliotibial band. If coexistent iliotibial bursitis is present, swelling and fluid accumulation that surrounds the bursa often is present.

Palpation of this area while having the patient flex and extend the knee may result in a creaking or “catching” sensation. Active resisted abduction of the lower extremity and passive adduction reproduce the pain. Sudden release of resistance during this maneuver markedly increases the pain. Pain is exacerbated by having the patient stand with all the weight on the affected extremity and then flexing the affected knee 30 to 40 degrees.

How is Runners knee diagnosed?

Plain radiographs of the knee may reveal calcification of the bursa and associated structures, including the iliotibial band tendon, consistent with chronic inflammation.

Magnetic resonance imaging (MRI) and ultrasound are indicated if runner’s knee, iliotibial band bursitis, internal derangement, occult mass, or tumor of the knee is suspected.

Electromyography helps distinguish iliotibial band bursitis from neuropathy, lumbar radiculopathy, and plexopathy. Injection of the iliotibial band at the friction point may serve as a diagnostic and therapeutic maneuver.

Differential Diagnosis

The most common cause of lateral knee pain is degenerative arthritis of the knee. Other pathological processes may mimic the pain and functional disability of runner’s knee. Lumbar radiculopathy may cause pain and disability similar to that of runner’s knee. In such patients, back pain is usually present, and the knee examination should be negative.

Entrapment neuropathies of the lower extremity, such as meralgia paresthetica, and bursitis of the knee also may confuse the diagnosis; both conditions may coexist with runner’s knee. Primary and metastatic tumors of the femur and proximal tibia and fibula may manifest in a manner analogous to runner’s knee.


Initial treatment of the pain and functional disability associated with runner’s knee should include a combination of nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and physical therapy. Local application of heat and cold may be beneficial. For patients who do not respond to these treatment modalities, injection of the iliotibial band at its friction point with a local anesthetic and steroid may be a reasonable next step.

The iliotibial band is injected by placing the patient in the supine position with a rolled blanket underneath the knee to flex the joint gently. The skin over the lateral epicondyle of the femur is prepared with antiseptic solution. A sterile syringe containing 2 mL of 0.25% preservative-free bupivacaine and 40 mg of methylprednisolone is attached to a 25-gauge, 11⁄2-inch needle using strict aseptic technique.

With strict aseptic technique, the iliotibial band bursa is located by identifying the point of maximal tenderness over the lateral condyle of the femur. The bursa usually is identified by point tenderness at that spot. At this point, the needle is inserted at a 45-degree angle to the femoral condyle to pass through the skin, subcutaneous tissues, and iliotibial band into the iliotibial band bursa. If the needle strikes the femur, it is withdrawn slightly into the substance of the bursa.

When the needle is in position in proximity to the iliotibial band bursa, the contents of the syringe are gently injected. Little resistance to injection should be noted. If resistance is encountered, the needle is probably in a ligament or tendon and should be advanced or withdrawn slightly until the injection proceeds without significant resistance.

The needle is removed, and a sterile pressure dressing and ice pack are placed at the injection site. Ultrasound guidance may increase the accuracy of needle placement and decrease the incidence of needle-related complications.

Complications and Pitfalls

Failure to identify primary or metastatic tumor of the knee or spine that is responsible for the patient’s pain may yield disastrous results. The major complication of injection of the iliotibial band bursa is infection.

This complication should be exceedingly rare if strict aseptic technique is followed. Approximately 25% of patients report a transient increase in pain after injection of the iliotibial band, and patients should be warned of this possibility.

Clinical Pearls

Coexistent bursitis and tendinitis may contribute to knee pain and may require additional treatment with more localized injection of a local anesthetic and depot steroid. Injection of the iliotibial band is extremely effective in the treatment of pain secondary to runner’s knee. This technique is a safe procedure if careful attention is paid to the clinically relevant anatomy in the areas to be injected. The use of physical modalities, including local heat and gentle range-of-motion exercises, should be introduced several days after the patient undergoes this injection technique for knee pain. Vigorous exercises should be avoided because they would exacerbate the patient’s symptoms.


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