Superficial Infrapatellar Bursitis

Abstract

The superficial infrapatellar bursa lies between the subcutaneous tissues and the upper part of the patellar ligament. This bursa may exist as a single bursal sac or, in some patients, as a multisegmented series of loculated sacs. The superficial infrapatellar bursa is vulnerable to injury from both acute trauma and repeated microtrauma. Acute injuries are caused by direct trauma to the bursa during falls onto the knee or patellar fracture. Overuse injuries are caused by running on soft or uneven surfaces or doing jobs that require crawling or kneeling, such as carpet laying or scrubbing floors. If inflammation of the superficial infrapatellar bursa becomes chronic, calcification may occur.

Patients with superficial infrapatellar bursitis complain of pain and swelling in the anterior knee over the patella that can radiate superiorly and inferiorly into the surrounding area. 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. Superficial infrapatellar bursitis often coexists with arthritis and tendinitis of the knee, which can confuse the clinical picture.

Keywords

superficial infrapatellat patellar bursitis, Housemaid’s knee pain, patellar tendon, overuse injury, diagnostic sonography, ultrasound guided procedure, magnetic resonance imaging, nonsteroidal antiinflammatory drugs, septic arthritis, Rice bodies

ICD-10 CODE M76.899

The Clinical Syndrome

The superficial infrapatellar bursa lies between the subcutaneous tissues and the upper part of the patellar ligament. This bursa may exist as a single bursal sac or, in some patients, as a multisegmented series of loculated sacs. The superficial infrapatellar bursa is vulnerable to injury from both acute trauma and repeated microtrauma. Acute injuries are caused by direct trauma to the bursa during falls onto the knee or patellar fracture. Overuse injuries are caused by running on soft or uneven surfaces or doing jobs that require crawling or kneeling, such as carpet laying or scrubbing floors ( Fig. 114.1 ). If inflammation of the superficial infrapatellar bursa becomes chronic, calcification may occur.

Signs and Symptoms

Patients with superficial infrapatellar bursitis complain of pain and swelling in the anterior knee over the patella that can radiate superiorly and inferiorly into the surrounding area. 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. Superficial infrapatellar bursitis often coexists with arthritis and tendinitis of the knee, which can confuse the clinical picture.

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 and patellar tendons, findings consistent with chronic inflammation ( Figs. 114.2 and 114.3 ). Other occult abnormalities may also be identified that may mimic the pain of infrapatellar bursitis ( Fig. 114.4 ). MRI is indicated if internal derangement, an occult mass, or a tumor of the knee is suspected. Electromyography can distinguish superficial infrapatellar bursitis from femoral neuropathy, lumbar radiculopathy, and plexopathy. The injection technique described later serves as both a diagnostic and a therapeutic maneuver. Antinuclear antibody testing is 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.