The quadriceps expansion is comprised of fibers of the quadriceps tendon, which pass on each side of the patella to form the medial and lateral patellar retinaculum (Fig. 141.1). These expansion fibers are susceptible to strain or sprain as the result of overuse or misuse of the knee as is seen in longdistance running or from direct trauma to the quadriceps tendon and patella from kicks or head butts. Often seen in conjunction with quadriceps expansion strains and sprains is acute calcific tendonitis of the quadriceps tendon. Calcific tendonitis of the quadriceps has a characteristic radiographic appearance of “whiskers” on the anterosuperior patella on both plain radiographs and magnetic resonance imaging (MRI) (Fig. 141.2).

Patients suffering from injury to the quadriceps expansions will complain of pain over the superior pole of the sesamoid, more commonly on the medial side. The pain is constant and is characterized as aching. The patient will note increased pain on walking down slopes or down stairs. The pain of quadriceps expansion injury may interfere with sleep. On physical examination, there is tenderness under the superior edge of the patella, occurring more commonly on the medial side. Patients suffering from damage of quadriceps expansion will exhibit a positive quadriceps expansion knee extension test. To perform the quadriceps expansion knee extension test, the clinician displaces the superior pole of the patella medially and then has the patient maximally flex his or her knee. The clinician then has the patient actively extend the affected knee against resistance. The test is considered positive if it reproduces the patient’s pain (Fig. 141.3). Coexistent suprapatellar and infrapatellar bursitis, tendonitis, arthritis, or internal derangement of the knee may confuse the clinical picture after trauma to the knee joint.

Plain radiographs are indicated in all patients who present with quadriceps expansion injury as not only quadriceps expansion pathology as well as other regional pathology including patellar abnormalities may be perceived as quadriceps expansion pain by the patient (Fig. 141.4). Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. MRI, computed tomography (CT), or ultrasound of the quadriceps expansions is indicated if the diagnosis is in question or if avascular necrosis, bursitis or meniscal tear, or patellar disease is suspected (Fig. 141.5).

The quadriceps tendon is made up of fibers from the four muscles that comprise the quadriceps muscle: the vastus lateralis, the vastus intermedius, the vastus medialis, and the rectus femoris (Fig. 141.6). These muscles are the primary extensors of the lower extremity at the knee. The tendons of these muscles converge and unite to form a single, exceedingly strong tendon. The patella functions as a sesamoid bone within the quadriceps tendon, with fibers of the tendon expanding around the patella and forming the medial and lateral patella retinacula, which help strengthen the knee joint. These fibers are called expansions and are subject to strain; the tendon proper is subject to the development of tendonitis. The suprapatellar, infrapatellar, and prepatellar bursae also may concurrently become inflamed with dysfunction of the quadriceps tendon.

The benefits, risks, and alternative treatments are explained to the patient and informed consent is obtained. The patient is then placed in the supine position with the lower extremity in neutral position and the arms crossed across the chest (Fig. 141.7). The skin overlying the patella and surrounding skin is then prepped with antiseptic solution. A sterile syringe containing 4.0 mL of 0.25% preservative-free bupivacaine and 40 mg of methylprednisolone is attached to a 1½-inch, 22-gauge needle using strict aseptic technique. A high-frequency linear ultrasound transducer is placed over the center of


the patella in the transverse plane (Fig. 141.8). A survey scan is taken, which demonstrates the characteristic appearance of the fibers of the quadriceps tendon passing over and inserting into the hyperechoic anterior margin of the dome-shaped patella (Fig. 141.9). The ultrasound transducer is then moved medially to identify the medial border of the patella and the quadriceps expansion lying adjacent to it (Figs. 141.10 and 141.11). After the medial quadriceps expansion is identified, the needle is placed through the skin ˜1 cm above the middle of the transversely placed ultrasound transducer and is then advanced using an out-of-plane approach with the needle trajectory adjusted under real-time ultrasound guidance until the needle tip lies in proximity to the medial quadriceps expansion as it abuts the medial border of the tibia (Fig. 141.12).