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 knees 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. Signs and symptoms
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.: p. 608  Unlike arthritis, except in severe cases  prepatellar bursitis generally does not affect the range of motion of the knee, though it may cause some discomfort in complete flexion of the joint.: p.
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.: p. 359  It is highly unusual for septic bursitis to be caused by anaerobes, fungi, or Gram-negative bacteria.: p. 608  In very rare cases, the infection can be caused by tuberculosis. Diagnosis
There are several types of inflammation that can cause knee pain, including sprains, bursitis, and injuries to the meniscus. A diagnosis of prepatellar bursitis can be made based on a physical examination and the presence of risk factors in the persons medical history; swelling and tenderness at the front of the knee, combined with a profession that requires frequent kneeling, suggest prepatellar bursitis. Swelling of multiple joints along with restricted range of motion may indicate arthritis instead.: p. 608 A physical examination and medical history are generally not enough to distinguish between infectious and non-infectious bursitis; aspiration of the bursal fluid is often required for this, along with a cell culture and Gram stain of the aspirated fluid.: p. 360  Septic prepatellar bursitis may be diagnosed if the fluid is found to have a neutrophil count above 1500 per microliter,: p. 608  a threshold significantly lower than that of septic arthritis (50,000 cells per microliter).: p. 360  A tuberculosis infection can be confirmed using a radiograph of the knee and urinalysis.