Septic arthritis
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2008-07-14T11:23:44Z
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{{Infobox_Disease
| Name = Septic arthritis
| Image =
| Caption =
| DiseasesDB = 29523
| ICD10 = {{ICD10|M|00||m|00}}-{{ICD10|M|03||m|00}}
| ICD9 = {{ICD9|711.0}}
| ICDO =
| OMIM =
| MedlinePlus =
| eMedicineSubj = med
| eMedicineTopic = 3394
| MeshID = D001170
}}
'''Septic arthritis''' is the invasion of a [[joint]] by an [[infectious]] agent which produces [[arthritis]]. The usual [[etiology]] is [[bacteria|bacterial]], but [[virus|viral]], [[mycobacteria|mycobacterial]], and [[fungus|fungal]] arthritis occur occasionally. Bacteria are carried by the bloodstream from an infectious focus elsewhere, introduced by a [[skin]] [[lesion]] that penetrates the joint, or by extension from adjacent tissue (e.g. bone or bursae).
==Etiology==
Micro-organisms must reach the [[synovial membrane]] of a joint. This can happen in any of the following ways:
* dissemination of [[pathogen|pathogens]] via the blood, from [[abscess|abscesses]] or wound infections,
* dissemination from an [[osteomyelitis|acute osteomyelitic focus]],
* dissemination from adjacent [[soft tissue]] infection,
* entry via [[penetrating trauma]]
* entry via [[iatrogenic]] means.<ref>Axford J, O'Callaghan C, (eds). 2004. Medicine. Oxford. Blackwell Publishing.</ref>
Bacteria that are commonly found to cause septic arthritis are:
* [[Staphylococcus aureus]] - the most common cause in adults
* [[Haemophilus influenzae]] - the most common cause in children
* [[gonorrhea|Neisseria gonorrhoea]] - in young adults
* [[Escherichia coli]] - in the elderly, IV drug users and the seriously ill
* [[M. tuberculosis]], [[Salmonella]] spp. and [[Brucella]] spp. - cause septic spinal arthritis <ref>Axford J, O'Callaghan C, (eds). 2004. Medicine. Oxford. Blackwell Publishing.</ref>
In bacterial infection, [[Pseudomonas aeruginosa]] has been found to infect joints, especially in children who have sustained a puncture wound. This bacteria also causes [[endocarditis]].<ref>[http://wordnet.com.au/Products/topics_in_infectious_diseases_Aug01.htm Topics in Infectious Diseases Newsletter, August 2001, Pseudomonas aeruginosa.]</ref>
== Indications ==
Septic arthritis should be suspected when '''one''' joint ([[monoarthritis]]) is affected and the patient is [[fever|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 [[microbiological culture|culture]] of fluid from the joint, as well as tell-tale signs in laboratory testing (such as a highly elevated [[neutrophils]] (approx. 90%), [[Erythrocyte sedimentation rate|ESR]] or [[CRP]]).
==Treatment==
Therapy is usually with [[intravenous]] [[antibiotic]]s, [[analgesia]] and washout/aspiration of the joint to dryness.
==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 concomitant 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]]
* [[Human biting injuries]]
* [[Transient synovitis]]
* [[Arthritis Care]]
==References==
<references/>
*[http://uwmsk.org/moodle/mod/resource/view.php?id=368 Septic arthritis] by William Brinkman, M.D., University of Washington Department of Radiology
* {{cite journal |author=Karchevsky M, Schweitzer ME, Morrison WB, Parellada JA |title=MRI findings of septic arthritis and associated osteomyelitis in adults |journal=AJR Am J Roentgenol |volume=182 |issue=1 |pages=119–22 |year=2004 |pmid=14684523 |doi= |url=http://www.ajronline.org/cgi/pmidlookup?view=long&pmid=14684523}}
* {{cite book |author=Resnick, Donald |title=Bone and joint imaging |publisher=Saunders |location=Philadelphia |year=1989 |pages=744-749 |isbn=0721622151 |oclc= |doi=}}
* {{cite book |author=Bredella, Miriam A.; Stoller, David W.; Tirman, Phillip F. J. |title=Diagnostic imaging |publisher=Amirsys |location=Salt Lake City, Utah |year=2004 |pages=4-99 |isbn=0-7216-2920-2 |oclc= |doi=}}
*Edwards MS. "Osteomyelitis and Septic Arthritis"
{{Diseases of the musculoskeletal system and connective tissue}}
[[Category:Arthritis]]
[[Category:Rheumatology]]
[[Category:Medical emergencies]]
[[it:Artrite settica]]
[[zh:敗血病關節炎]]