Abstract
The suprapatellar bursa extends superiorly from beneath the patella under the quadriceps femoris muscle and its tendon. The bursa is held in place by a small portion of the vastus intermedius muscle called the articularis genus muscle. The suprapatellar bursa may exist as a single bursal sac or, in some patients, as a multisegmented series of loculated sacs. The suprapatellar bursa is vulnerable to injury from both acute trauma and repeated microtrauma. Acute injuries may be caused by direct trauma to the bursa during falls onto the knee or patellar fractures. Overuse injuries may result from running on soft or uneven surfaces or from jobs that require crawling on the knees, such as carpet laying. If inflammation of the suprapatellar bursa becomes chronic, calcification may occur.
Patients suffering from suprapatellar bursitis complain of pain in the anterior knee above the patella that may radiate superiorly into the distal anterior thigh. Often, patients are unable to kneel or walk down stairs. Patients may also complain of a sharp “catching” sensation with range of motion of the knee, especially on first arising. Suprapatellar bursitis often coexists with arthritis and tendinitis of the knee, thus confusing the clinical picture.
Keywords
suprapatellar bursitis, knee pain, quadriceps femoris muscle, overuse injury, diagnostic sonography, ultrasound guided procedure, magnetic resonance imaging, nonsteroidal anti-inflammatory drugs, septic arthritis, Rice bodies
ICD-10 CODE M70.50
Keywords
suprapatellar bursitis, knee pain, quadriceps femoris muscle, overuse injury, diagnostic sonography, ultrasound guided procedure, magnetic resonance imaging, nonsteroidal anti-inflammatory drugs, septic arthritis, Rice bodies
ICD-10 CODE M70.50
The Clinical Syndrome
The suprapatellar bursa extends superiorly from beneath the patella under the quadriceps femoris muscle and its tendon. The bursa is held in place by a small portion of the vastus intermedius muscle called the articularis genus muscle. The suprapatellar bursa may exist as a single bursal sac or, in some patients, as a multisegmented series of loculated sacs. The suprapatellar bursa is vulnerable to injury from both acute trauma and repeated microtrauma. Acute injuries may be caused by direct trauma to the bursa during falls onto the knee or patellar fractures. Overuse injuries may result from running on soft or uneven surfaces or from jobs that require crawling on the knees, such as carpet laying. If inflammation of the suprapatellar bursa becomes chronic, calcification may occur.
Signs and Symptoms
Patients suffering from suprapatellar bursitis complain of pain in the anterior knee above the patella that may radiate superiorly into the distal anterior thigh. Often, patients are unable to kneel or walk down stairs ( Fig. 112.1 ). Patients may also complain of a sharp “catching” sensation with range of motion of the knee, especially on first arising. Suprapatellar bursitis often coexists with arthritis and tendinitis of the knee, thus confusing the clinical picture.
Physical examination may reveal point tenderness in the anterior knee just above the patella. Passive flexion and active resisted extension of the knee reproduce the pain. Sudden release of resistance during this maneuver causes a marked increase in pain. The patient may have swelling in the suprapatellar region, with a boggy feeling on palpation. Occasionally, the suprapatellar bursa becomes infected, with systemic symptoms such as fever and malaise, as well as local symptoms such as rubor, color, and dolor.
Testing
Plain radiographs, ultrasound imaging, and magnetic resonance imaging (MRI) of the knee may reveal calcification of the bursa and associated structures, including the quadriceps tendon, findings consistent with chronic inflammation ( Figs. 112.2 and 112.3 ). MRI and ultrasound imaging are indicated if internal derangement, an occult mass, or a tumor of the knee is suspected. Positron emission tomography may help identify infection of the suprapatellar bursa ( Fig. 112.4 ). Electromyography can distinguish suprapatellar bursitis from femoral neuropathy, lumbar radiculopathy, and plexopathy. The injection technique described later serves as both a diagnostic and a therapeutic maneuver. A complete blood count, automated chemistry profile including uric acid level, erythrocyte sedimentation rate, and antinuclear antibody testing are indicated if collagen vascular disease is suspected. If infection is a possibility, aspiration, Gram stain, and culture of bursal fluid should be performed on an emergency basis.
