Septic arthritis: Difference between revisions
(Major expansion: arthrocentesis interpretation, empiric antibiotics, gonococcal specifics, peer-reviewed references) |
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*Bacterial infection of a joint space — a '''true orthopedic emergency''' | *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> | *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%) | *Knee is the most commonly affected joint (~50%) | ||
*Mortality: 5-15% overall; higher in elderly and prosthetic joints | *Mortality: 5-15% overall; higher in elderly and prosthetic joints | ||
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==Clinical Features== | ==Clinical Features== | ||
* | *Acute monoarticular joint pain, swelling, warmth, erythema | ||
*Pain with both active | *Pain with both active and passive range of motion (distinguishes from periarticular pathology) | ||
*Effusion | *Effusion | ||
*Fever (present in ~60%, absence does not exclude) | *Fever (present in ~60%, absence does not exclude) | ||
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**Lower counts do not exclude — partially treated or early infection may have lower counts | **Lower counts do not exclude — partially treated or early infection may have lower counts | ||
**Gram stain positive in ~50% of non-gonococcal cases | **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) | *If gonococcal suspected: GC/CT NAAT (urine, cervix/urethra, pharynx, rectum) | ||
* | *Imaging: | ||
**X-ray: evaluate for effusion, osteomyelitis, fracture | **X-ray: evaluate for effusion, osteomyelitis, fracture | ||
**Ultrasound: guide arthrocentesis, confirm effusion | **Ultrasound: guide arthrocentesis, confirm effusion | ||
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==Management== | ==Management== | ||
*'''Empiric IV antibiotics''' after arthrocentesis (do NOT delay if aspiration will be delayed): | *'''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 | **If prosthetic joint: add Vancomycin + Cefepime or Meropenem | ||
* | *Orthopedic consultation for: | ||
**Joint washout/irrigation (arthroscopic or open) | **Joint washout/irrigation (arthroscopic or open) | ||
**Prosthetic joint infections require urgent surgical intervention | **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 | *Pain management: IV analgesics, joint immobilization, ice | ||
==Disposition== | ==Disposition== | ||
* | *Admit all confirmed or suspected septic arthritis | ||
*Orthopedic surgery consultation for joint washout | *Orthopedic surgery consultation for joint washout | ||
*Gonococcal arthritis: may be managed with close outpatient follow-up after initial IV antibiotics in select cases | *Gonococcal arthritis: may be managed with close outpatient follow-up after initial IV antibiotics in select cases | ||
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