Acute inflammation of one or more joints caused by infection. Suppurative arthritis may follow certain bacterial infections; joints become swollen, hot, sore, and filled with pus, which erodes their cartilage, causing permanent damage if not promptly treated by giving antibiotics, draining the pus, and resting the joint. Nonsuppurative arthritis can accompany several diseases caused by bacteria, viruses, or fungi; joints become stiff, swollen, and painful to move. Treatment includes rest, drugs, and, in the case of tuberculosis, orthopedic care to prevent skeletal deformity.
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Bacteria that are commonly found to cause septic arthritis are:
Septic arthritis should be suspected when one joint (monoarthritis) is affected and the patient is febrile. In seeding arthritis, several joints can be affected simultaneously; this is especially the case when the infection is caused by staphylococcus or gonococcus bacteria.
Diagnosis is by aspiration (giving a turbid, non-viscous fluid), Gram stain and culture of fluid from the joint, as well as tell-tale signs in laboratory testing (such as a highly elevated neutrophils (approx. 90%), ESR or CRP).
Plain film findings of septic arthritis include: joint effusion, soft tissue swelling, periarticular osteoporosis, loss of joint space, marginal and central erosions and bone ankylosis. CT is more sensitive than plain films for the detection of early bone destruction and effusion.
The role of MRI in the diagnosis of septic arthritis has been increasing in recent years in an effort to detect this entity earlier. Findings are usually evident within 24 hours following the onset of infection and include: synovial enhancement, perisynovial edema and joint effusion. Signal abnormalities in the bone marrow can indicate a concomitant osteomyelitis. The sensitivity and specificity of MRI for the detection of septic arthritis has been reported to be 100% and 77% respectively.