Prepatellar bursitis, also known as Housemaid's knee, is a common cause of swelling and pain above the patella (kneecap), and is due to inflammation of the prepatellar bursa

Prepatellar bursa

The prepatellar bursa is a frontal bursa of the knee joint. It is a superficial bursa with a thin synovial lining located between the skin and the patella.-Pathology:...

. This structure is a superficial bursa

Bursa (anatomy)

A bursa is a small fluid-filled sac lined by synovial membrane with an inner capillary layer of slimy fluid . It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce friction between the bones and allows free movement...

 with a thin synovial

Synovium

Synovial membrane is the soft tissue found between the articular capsule and the joint cavity of synovial joints....

 lining located between the skin and the patella. The bursa develops within the first years of life as a result of mechanical pressure and friction, and it serves the purpose of reducing friction on underlying structures and allowing maximal range of motion in the knee.
Aseptic prepatellar bursitis is commonly caused by repetitive work in a kneeling position, hence the name "housemaid's knee".

Inflammation of the prepatellar bursa may be aseptic (most common) or septic (e.g. bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

l infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

), the septic variants being most common in children and immunocompromised

Immunodeficiency

Immunodeficiency is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Immunodeficiency may also decrease cancer immunosurveillance. Most cases of immunodeficiency are acquired but some people are born with defects in their immune system,...

 individuals. Prepatellar bursitis is more common in men than women.

Treatment

Aseptic bursitis is usually managed conservatively, but complicated cases may be treated with oral NSAIDs

Non-steroidal anti-inflammatory drug

Nonsteroidal anti-inflammatory drugs, usually abbreviated to NSAIDs or NAIDs, but also referred to as nonsteroidal anti-inflammatory agents/analgesics or nonsteroidal Anti-inflammatory medicines , are drugs with analgesic and antipyretic effects and which have, in higher doses, anti-inflammatory...

 or corticosteroid

Corticosteroid

Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...

 injections when infection has been ruled out. Surgical excision

Excision

Excision is the alias of Jeff Abel, a dubstep DJ and music boss from British Columbia, Canada. He frequently works with fellow Canadian dubstep producers Datsik and Downlink. As one of the first dubstep producers and DJs in North America, he has played a significant role in the genre's growth in...

 is seldom necessary. Acute bursitis can develop into a chronic issue if the cause is not identified and addressed.