Abstract
The deep infrapatellar bursa lies between the patellar ligament and the tibia. This bursa may exist as a single bursal sac or, in some patients, as a multisegmented series of loculated sacs. The deep 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 jobs that require crawling and kneeling, such as carpet laying or scrubbing floors. If inflammation of the deep infrapatellar bursa becomes chronic, calcification may occur.
Patients with deep infrapatellar bursitis complain of pain and swelling in the anterior knee below the patella that can radiate inferiorly into the surrounding area. Often, patients are unable to kneel or walk down stairs. They may also complain of a sharp “catching” sensation with range of motion of the knee, especially on first arising. Infrapatellar bursitis often coexists with arthritis and tendinitis of the knee, which can confuse the clinical picture.
Keywords
deep infrapatellar patellar bursitis, 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 deep infrapatellar bursa lies between the patellar ligament and the tibia. This bursa may exist as a single bursal sac or, in some patients, as a multisegmented series of loculated sacs. The deep 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 ( Fig. 115.1 ) or patellar fracture. Overuse injuries are caused by running on soft or uneven surfaces or jobs that require crawling and kneeling, such as carpet laying or scrubbing floors. If inflammation of the deep infrapatellar bursa becomes chronic, calcification may occur.
Signs and Symptoms
Patients with deep infrapatellar bursitis complain of pain and swelling in the anterior knee below the patella that can radiate inferiorly into the surrounding area. Often, patients are unable to kneel or walk down stairs. They may also complain of a sharp “catching” sensation with range of motion of the knee, especially on first arising. Infrapatellar bursitis often coexists with arthritis and tendinitis of the knee, which can confuse the clinical picture.
Physical examination may reveal point tenderness in the anterior knee just below the patella. Swelling and fluid accumulation surrounding the lower patella are often present ( Fig. 115.2 ). 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 deep infrapatellar bursa is not as susceptible to infection as is the superficial infrapatellar bursa.
Testing
Plain radiographs, ultrasound, 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. 115.3 and 115.4 ). MRI and ultrasound imaging is indicated if internal derangement, an occult mass, or a tumor of the knee is suspected as well as to identify other causes of the patient’s knee pain ( Fig. 115.5 ). Electromyography can distinguish deep 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.
