Septic arthritis: Difference between revisions
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== | ==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: | [[Category:Orthopedics]] | ||
[[Category: | [[Category:Infectious Disease]] | ||
Latest revision as of 09:31, 22 March 2026
Background
- Bacterial infection of a joint space — a true orthopedic emergency
- Rapid cartilage destruction occurs within hours if untreated[1]
- 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
Evaluation
- Arthrocentesis — must be performed in any suspected septic joint[2]
- 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