Prepatellar bursitis

Inflammation of the prepatellar bursa at the front of the knee

Prepatellar bursitis is an inflammation of the prepatellar bursa at the front of the knee. It is marked by swelling at the knee, which can be tender to the touch and which generally does not restrict the knee's range of motion. It can be extremely painful and disabling as long as the underlying condition persists. Prepatellar bursitis is most commonly caused by trauma to the knee, either by a single acute instance or by chronic trauma over time. As such, the condition commonly occurs among individuals whose professions require frequent kneeling. A definitive diagnosis can usually be made once a clinical history and physical examination have been obtained, though determining whether or not the inflammation is septic is not as straightforward. Treatment depends on the severity of the symptoms, with mild cases possibly only requiring rest and localized icing. Options for presentations with severe sepsis include intravenous antibiotics, surgical irrigation of the bursa, and bursectomy.

The primary symptom of prepatellar bursitis is swelling of the area around the kneecap. It generally does not produce a significant amount of pain unless pressure is applied directly. The area may be red (erythema), warm to the touch, or surrounded by cellulitis, particularly if infection is present, often accompanied by fever. Flexion and extension of the knee may be accompanied by crepitus, the audible grating of bones, ligaments, or particles within the excess synovial fluid.

In human anatomy, a bursa is a small pouch filled with synovial fluid. Its purpose is to reduce friction between adjacent structures. The prepatellar bursa is one of several bursae of the knee joint, and is located between the patella and the skin. Prepatellar bursitis is an inflammation of this bursa. Bursae are readily inflamed when irritated, as their walls are very thin. Prepatellar bursitis is caused by either a single instance of acute trauma to the knee, or repeated minor trauma to the knee. The trauma can cause extravasation of nearby fluids into the bursa, which stimulates an inflammatory response. This response occurs in two phases: The vascular phase, in which the blood flow to the surrounding area increases, and the cellular phase, in which leukocytes migrate from the blood to the affected area. The prepatellar bursa and the olecranon bursa are the two bursae that are most likely to become infected, or septic. Septic bursitis typically occurs when the trauma to the knee causes an abrasion, though it is also possible for the infection to be caused by bacteria traveling through the blood from a pre existing infection site. In approximately 80% of septic cases, the infection is caused by Staphylococcus aureus; other common infections are Streptococcus, Mycobacterium, and Brucella.

There are several types of inflammation that can cause knee pain, including sprains, bursitis, and injuries to the meniscus. Severe cases may require fine needle aspiration of the bursa fluid, sometimes coupled with cortisone injections. After the bursitis has been treated, rehabilitative exercise may help improve joint mechanics and reduce chronic pain. Opinions vary as to which treatment options are most effective for septic prepatellar bursitis. Some authors suggest surgical irrigation of the bursa by means of a subcutaneous tube. Others suggest that bursectomy may be necessary for intractable cases; the operation is an outpatient procedure that can be performed in less than half an hour.

The various nicknames associated with prepatellar bursitis arise from the fact that it commonly occurs among those individuals whose professions require frequent kneeling, such as carpenters, carpet layers, gardeners, housemaids, mechanics, miners, plumbers, and roofers.