Bursitis is an inflammation or degeneration of the sac-like structures that protect the soft tissues from underlying bony prominences . Septic bursitis refers to inflammation of the bursa that is due to infection, typically resulting from bacterial inoculation that is direct (eg, puncture wound), spread from nearby soft tissues (eg, cellulitis), or hematogenous (eg, bacterial endocarditis).
Nonseptic bursitis due to trauma, repetitive injury, crystal diseases, and other systemic disorders is discussed separately. (See "Bursitis: An overview of clinical manifestations, diagnosis, and management".)
ETIOLOGY AND PATHOGENESIS
There are more than 150 bursae in the human body. Bursae may be divided by location into those that are superficial or deep. Superficial bursae are subcutaneous and separate skin from deeper tissues such as periosteum or ligaments. Deep bursae serve to reduce friction between fibrous structures, such as tendons, from adjacent bone. Bursae are lined by synovial cells, which under ordinary circumstances produce a small amount of lubricating fluid.
Factors that increase the risk of septic bursitis include loss of skin integrity, impaired response to infection (eg, diabetes mellitus, alcohol abuse), and host factors that lead to an increased amount of bursal fluid or tissue (such as rheumatoid arthritis or tophaceous gout) [2-4]. One study of septic olecranon bursitis found that one-third of patients had at least one comorbid illness . It is unclear whether immunosuppressed states such as HIV/AIDS increase the risk of septic bursitis [6,7].
Superficial bursae — The superficial or subcutaneous bursae are predisposed to infection as a result of skin trauma. The most common mechanisms involved in septic superficial bursitis consist of direct inoculation due to puncture of the overlying skin or contiguous spread from cellulitis [2,6]. The majority of reported cases have been in men [5,8-10]. Trauma to the skin and bursa may be occupational, due to recreational activities, or related to concomitant disease. Among these the following are notable [6,11-13]: