Septic arthritis

Septic arthritis is the proliferation of bacteria in joints and resultant inflammation. Bacteria are either carried by the bloodstream from an infectious focus elsewhere or are introduced by a skinlesionthat penetrates the joint.

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 staphylococcusor gonococcusbacteria.

Diagnosis is by aspiration, Gram stainand cultureof fluid from the joint, as well as telltale signs in laboratory testing (such as a highly elevated ESRor CRP).

Therapy is usually with intravenousantibiotics.

Radiologic Findings

Traditionally, the diagnosis of septic arthritis was based on clinical assessment and prompt arthrocentesis. However, the clinical picture may be obscured by multiple confounding factors and a paucity of specific findings especially for the deep joints, ie. the hip or shoulder. Imaging can be used to confirm the diagnosis of septic arthritis and more importantly, imaging findings suggestive of septic arthritis can direct the clinician to a diagnosis that may not have been considered.

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 concomittant osteomyelitis. The sensitivity and specificity of MRI for the detection of septic arthritis has been reported to be 100% and 77% respectively.

See also

• Arthritis

References

• Septic arthritisby William Brinkman, M.D., University of Washington Department of Radiology
• Karchevsky M, Schweitzer ME, Morrison WB, Parellada JA. MRI findings of septic arthritis and associated osteomyelitis in adults. AJR 2004; 182:119-122.
• Resnick D. Bone and joint imaging. Philadelphia, PA: WB Saunders Co; 1989; 744-749
• Stoller DW, Tirman P, Bredella MA. Diagnostic imaging orthopaedics. Salt Lake City, UT: Amirsys; 2004; 4-99.

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It uses material from the http://en.wikipedia.org/wiki/Septic+arthritis Wikipedia article Septic arthritis.