Ver el código de «Septic arthritis»

==Background==
*Bacterial infection of a joint space — a '''true orthopedic emergency'''
*Rapid cartilage destruction occurs within hours if untreated<ref name="mathews">Mathews CJ, et al. Bacterial septic arthritis in adults. ''Lancet''. 2010;375(9717):846-855. PMID 20206778.</ref>
*Staphylococcus aureus is the most common pathogen in adults (~50%)
*Neisseria gonorrhoeae is the most common cause in sexually active young adults
*Knee is the most commonly affected joint (~50%)
*Mortality: 5-15% overall; higher in elderly and prosthetic joints

==Risk Factors==
*Pre-existing joint disease (rheumatoid arthritis, osteoarthritis)
*Prosthetic joint
*Recent joint surgery or injection
*IV drug use
*Immunosuppression (diabetes, HIV, steroids)
*Skin infection or bacteremia
*Advanced age

==Clinical Features==
*Acute monoarticular joint pain, swelling, warmth, erythema
*Pain with both active and passive range of motion (distinguishes from periarticular pathology)
*Effusion
*Fever (present in ~60%, absence does not exclude)
*In gonococcal arthritis: migratory polyarthralgias, tenosynovitis, dermatitis (pustular skin lesions), may involve multiple joints
*Prosthetic joint infection: may have subtle presentation with chronic pain and loosening

==Differential Diagnosis==
*[[Gout]] / [[Pseudogout]] (crystal arthropathy)
*[[Reactive arthritis]]
*[[Rheumatoid arthritis]] flare
*Hemarthrosis
*[[Lyme disease]] (Lyme arthritis)
*Viral arthritis
*[[Osteomyelitis]] with joint extension
*Periarticular abscess or [[Bursitis|bursitis]]

==Evaluation==
*'''Arthrocentesis''' — '''must be performed''' in any suspected septic joint<ref name="long">Long B, et al. Evaluation and Management of Septic Arthritis and its Mimics in the Emergency Department. ''West J Emerg Med''. 2019;20(2):331-341. PMID 30881554.</ref>
**Send for: cell count with differential, Gram stain, culture, crystal analysis
**WBC >50,000/mm³ with >90% PMNs strongly suggests infection
**WBC >100,000/mm³ is virtually diagnostic
**Lower counts do not exclude — partially treated or early infection may have lower counts
**Gram stain positive in ~50% of non-gonococcal cases
*Labs: CBC, ESR, CRP, blood cultures (positive in ~50%), lactate
*If gonococcal suspected: GC/CT NAAT (urine, cervix/urethra, pharynx, rectum)
*Imaging: 
**X-ray: evaluate for effusion, osteomyelitis, fracture
**Ultrasound: guide arthrocentesis, confirm effusion
**MRI if concerned for adjacent osteomyelitis

==Management==
*'''Empiric IV antibiotics''' after arthrocentesis (do NOT delay if aspiration will be delayed):
**Vancomycin 15-20 mg/kg IV (covers MRSA) PLUS
**Ceftriaxone 2 g IV (covers gram-negatives and gonococcus)
**If prosthetic joint: add Vancomycin + Cefepime or Meropenem
*Orthopedic consultation for:
**Joint washout/irrigation (arthroscopic or open)
**Prosthetic joint infections require urgent surgical intervention
*Gonococcal arthritis: Ceftriaxone 1 g IV/IM daily + treat for chlamydia
*Pain management: IV analgesics, joint immobilization, ice

==Disposition==
*Admit all confirmed or suspected septic arthritis
*Orthopedic surgery consultation for joint washout
*Gonococcal arthritis: may be managed with close outpatient follow-up after initial IV antibiotics in select cases

==See Also==
*[[Gout]]
*[[Pseudogout]]
*[[Osteomyelitis]]
*[[Prosthetic joint infection]]
*[[Arthrocentesis]]

==References==
<references/>

[[Category:Orthopedics]]
[[Category:Infectious Disease]]