Abstract
The prepatellar bursa lies between the subcutaneous tissues and the patella. This bursa is held in place by the patellar ligament. The prepatellar bursa may exist as a single bursal sac or, in some patients, as a multisegmented series of loculated sacs. The prepatellar 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 may be caused by running on soft or uneven surfaces or jobs that require crawling or kneeling, such as carpet laying or scrubbing floors, hence the other name for prepatellar bursitis: housemaid’s knee. If inflammation of the prepatellar bursa becomes chronic, calcification may occur.
Patients suffering from prepatellar 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. Prepatellar bursitis often coexists with arthritis and tendinitis of the knee, which can confuse the clinical picture.
Keywords
prepatellar bursitis, Housemaid’s knee pain, quadriceps femoris muscle, overuse injury, diagnostic sonography, ultrasound guided procedure, magnetic resonance imaging, nonsteroidal antiinflammatory drugs, septic arthritis, Rice bodies
ICD-10 CODE M70.40
The Clinical Syndrome
The prepatellar bursa lies between the subcutaneous tissues and the patella. This bursa is held in place by the patellar ligament. The prepatellar bursa may exist as a single bursal sac or, in some patients, as a multisegmented series of loculated sacs ( Fig. 113.1 ). The prepatellar 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 may be caused by running on soft or uneven surfaces or jobs that require crawling or kneeling, such as carpet laying or scrubbing floors, hence the other name for prepatellar bursitis: housemaid’s knee ( Fig. 113.2 ). If inflammation of the prepatellar bursa becomes chronic, calcification may occur.
Signs and Symptoms
Patients suffering from prepatellar bursitis complain of pain and swelling in the anterior knee over the patella that can radiate superiorly and inferiorly into the surrounding area ( Fig. 113.3 ). 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. Prepatellar bursitis often coexists with arthritis and tendinitis of the knee, which can confuse the clinical picture.
Testing
Plain radiographs and magnetic resonance imaging (MRI) of the knee may reveal calcification of the bursa and associated structures, including the quadriceps tendon, consistent with chronic inflammation ( Fig. 113.4 ). MRI is indicated if internal derangement, an occult mass, infection, or a tumor of the knee is suspected ( Fig. 113.5 ). Ultrasound imaging can also help clarify the diagnosis ( Figs. 113.6 and 113.7 ). Electromyography can distinguish prepatellar 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.
