The patellar tendon, which is also known as the patellar ligament, originates at the superior pole of the patella and is comprised of fibers from the quadriceps tendon, which pass over the top of and on each side of the patella and each side for patella to ultimately insert on the tibial tuberosity (Fig. 142.1). The fibers of the patellar tendon are susceptible to strain or sprain as the result of overuse or misuse for knee as is seen in long-distance running or from direct trauma to the quadriceps tendon and patella from kicks or head butts. A distinct clinical entity from tendonitis of the patellar tendon, jumper’s knee, is a tendinopathy resulting from a repetitive stress disorder that is thought to be the result of the strong eccentric contraction of the quadriceps muscle that is necessary to strengthen the knee joint during landing rather than from the jump itself. Tendonitis of the quadriceps or patellar tendons or quadriceps expansion syndrome may coexist with jumper’s knee and confuse the clinical picture. Congenital variants of the anatomy of the knee such as patella alta or baja and limb-length discrepancies as well as weak or poor quadriceps and hamstring muscle flexibility as well as have also been implicated as risk factors for the development of jumper’s knee (Fig. 142.2).

Patients suffering from injury to the jumper’s knees will complain of pain over the superior and/or inferior poles of the patella. Unlike quadriceps expansion syndrome, which has a predilection for the medial side of the patella, jumper’s knee can afflict both the medial and lateral tendon fibers. Frequently, the patient suffering from jumper’s knee will bitterly complain of increased pain when walking down stairs or slopes, especially on uneven surfaces as when hiking. The pain is constant and is characterized as aching with activity exacerbating the pain. The pain of jumper’s knee injury may interfere with sleep. On physical examination, there is tenderness of the quadriceps and/or patellar tendons. A joint effusion may be appreciated on ballottement of the patella (Figs. 142.3 and 142.4). Active resisted extension of the knee reproduces the pain. Coexistent suprapatellar and infrapatellar bursitis, tendonitis, arthritis, or internal derangement for knee may confuse the clinical picture after trauma to the knee joint.

Plain radiographs are indicated in all patients who present with jumper’s knee as not only jumper’s knee tendinopathy, as well as other regional pathology including quadriceps and patellar tendonitis and patellar abnormalities may be perceived as jumper’s knee pain by the patient. Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging (MRI), computed tomography (CT), or ultrasound for jumper’s knees is indicated if the diagnosis is in question or if avascular necrosis, bursitis or meniscal tear, or patellar disease is suspected (Figs. 142.5 and 142.6).

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. 142.7). These muscles are the primary extensors for 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 for 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. These fibers continue as the patellar tendon, which originates at the superior pole of the patella and is comprised of fibers from quadriceps tendon, which pass over the top of and on each side of the patella and each side for patella to ultimately insert on the tibial tuberosity. The suprapatellar, infrapatellar, and prepatellar bursae also may concurrently become inflamed with dysfunction of the quadriceps and patellar tendons.

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. 142.8). The skin overlying the patella and surrounding skin knee 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. 142.9). A survey scan is taken, which demonstrates the characteristic appearance for the fibers of the quadriceps tendon passing over and inserting into the hyperechoic anterior margin for dome-shaped patella (Fig. 142.10). The ultrasound transducer is then moved inferiorly to identify the inferior border for patella and the fibers of the patellar tendon lying inferior to the patella (Fig. 142.11). After the proximal patellar tendon is identified, the needle is placed through the skin ˜1 cm below the middle for 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 patellar tendon as it abuts the inferior pole of the patella (Fig. 142.12).