Quadriceps Tendon Injection

Indications and Clinical Considerations

Patients suffering from injury to the quadriceps tendon will complain of pain over the superior pole of the patella, 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 stairs. The pain of quadriceps tendon injury may interfere with sleep. Activity using the knee makes the pain worse; rest and heat provide some relief. On physical examination, there is tenderness of the quadriceps tendon, and a joint effusion may be present. Active resisted extension of the knee reproduces the pain. To perform the quadriceps tendon 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 extension against resistance reproduces the patient’s pain ( Fig. 156.1 ). Coexistent suprapatellar and infrapatellar bursitis, tendinitis, arthritis, or internal derange-ment of the knee may confuse the clinical picture after trauma to the knee joint. The quadriceps tendon also is subject to acute calcific tendinitis, which may coexist with acute strain injuries as well as the more chronic changes of tendinosis. Calcific tendinitis of the quadriceps has a characteristic radiographic appearance of “whiskers” on the anterior superior patella ( Fig. 156.2 ).

FIG. 156.1, Patients suffering from quadriceps expansion syndrome will exhibit a positive quadriceps expansion knee extension test. A, To perform the quadriceps expansion knee extension test knee, the clinician displaces the superior pole of the patella medially and then has the patient maximally flex his or her knee. B, The clinician then has the patient actively extend the affected knee against resistance. The test is positive if the pain is reproduced.

FIG. 156.2, Lateral radiograph of the knee showing amorphous whisker-like calcifications at the superior pole of patella.

Plain radiographs are indicated for all patients with knee pain. On the basis of the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging and/or ultrasound imaging of the knee is indicated if there is a suspicion of rupture of the quadriceps tendon and to identify other pathology that may be responsible for the patient’s pain symptomatology ( Figs. 156.3 and 156.4 ). Bone scan may be useful for identifying occult stress fractures involving the joint, especially if trauma has occurred.

FIG. 156.3, Magnetic resonance imaging is useful for distinguishing between partial and complete quadriceps tendon ruptures. Findings often include a gap in the quadriceps tendon with a wavy patella tendon suggesting laxity.

FIG. 156.4, Longitudinal ultrasound image demonstrating suprapatellar bursitis in a patient with anterior knee pain.

Clinically Relevant Anatomy

The quadriceps tendon is made up of fibers from the 4 muscles that constitute the quadriceps muscle: the vastus lateralis, the vastus intermedius, the vastus medialis, and the rectus femoris ( Fig. 156.5 ). 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 ( Figs. 156.6 and 156.7 ). 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 patellar 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 tendinitis. The suprapatellar, infrapatellar, and prepatellar bursae also may concurrently become inflamed with dysfunction of the quadriceps tendon. The patellar tendon extends from the patella to the tibial tuberosity. It is also called the patellar ligament (see Figs. 156.6 and 156.7 ).