Septic arthritis: Difference between revisions

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== Background ==
==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


*Inflammation of synovial membrane with purulent effusion into the joint capsule
==Risk Factors==
*Knee most commonly involved in adults; hip most common in peds
*Pre-existing joint disease (rheumatoid arthritis, osteoarthritis)
*Most often seen in pts &gt;65yr
*Prosthetic joint
*Most commonly bacterial (gonococcal vs nongonococcal)
*Recent joint surgery or injection
*IV drug use
*Immunosuppression (diabetes, HIV, steroids)
*Skin infection or bacteremia
*Advanced age


== Clinical Features ==
==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


*Fever
==Differential Diagnosis==
*Warm, red, painful, swollen joint
*[[Gout]] / [[Pseudogout]] (crystal arthropathy)
*Decreased range of motion (even passively)
*[[Reactive arthritis]]
*[[Rheumatoid arthritis]] flare
*Hemarthrosis
*[[Lyme disease]] (Lyme arthritis)
*Viral arthritis
*[[Osteomyelitis]] with joint extension
*Periarticular abscess or [[Bursitis|bursitis]]


== Diagnosis ==
==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


*Arthrocentesis for synoval fluid
==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


{| width="400" border="1" cellpadding="1" cellspacing="1"
==Disposition==
|-
*Admit all confirmed or suspected septic arthritis
|
*Orthopedic surgery consultation for joint washout
| Normal
*Gonococcal arthritis: may be managed with close outpatient follow-up after initial IV antibiotics in select cases
| Noninflammatory
| Inflammatory
| Septic
|-
| Clarity
| Transparent
| Transparent
| Cloudy
| Cloudy
|-
| Color
| Clear
| Yellow
| Yellow
| Yellow
|-
| WBC
| &lt;200
| &lt;200-2000
| 200-50,000
| &gt;25,000
|-
| PMN
| &lt;25%
| &lt;25%
| &gt;50%
| &gt;90%
|-
| Culture
| Neg
| Neg
| Neg
| &gt;50% positive
|-
| Crystals
| None
| None
| Multiple or none
| None
|}


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


== Work-Up ==
==References==
<references/>


#Arthrocentesis with synovial fluid analysis
[[Category:Orthopedics]]
#CBC
[[Category:Infectious Disease]]
#ESR/CRP
#Blood Culture
#Gonorrhea culture (urethral/cervical/pharyngeal/rectal)
#Plain films (often normal but may show widening of joint space or evidence of osteomyelitis)
#Ultrasound (can show joint effusion, extent of disease, and may help differentiate from other conditions)
 
== DDx ==
 
#Toxic synovitis
#Abscess
#Cellulitis
#Primary rheumatologic disorder (i.e. vasculitis)
#Iatrogenic
#Reactive arthritis (post-infectious)
 
== Gonococcal Arthritis ==
 
Healthy, young sexually active adults
 
Women &gt; men
 
Suppurative monoarthritis (may be preceded by polyarthralgias)
 
Knee, wrist, ankle
 
== Arthritis-Dermatitis Syndrome ==
 
=== Diagnosis ===
 
#Triad: dermatitis, tenosynovitis, migratory polyarthritis (hematogenous spread of bacteria and immune complexes)
#Skin lesions: scattered small painless erythematous macules or petechiae--&gt;pustular --&gt;necrotic lesions
#Transient painful extensor tenosynovitis (writs, hands, ankles)
#Asymmtric polyarthralgia of extremity joints
#Diagnosis Cx everything - jt, mucosal surfaces, lesions
 
=== Treatment ===
 
CTX 1gIV qd OR
 
Cefotax 1g q8
 
Empirically treat Chlamydia
 
== Nongonococcal Arthritis ==
 
=== Background ===
 
Fulminant presentation (abrupt, swelling, toxicity and fever) unless elderly
 
#Hematogenous
#Contiguous
#Direct traumatic implantation
#Postop
 
=== Causes ===
 
#Bacterial
#Mycobacterial
#Spirochete (lyme, syphilis)
#Fungal
#Viral (HIV, Hep B, Rubella, etc)
#Postinfectious
 
=== Diagnosis ===
 
#Synovial fluid aspiration
#Cx - if only one test, use BCx bottles (may enhance yield)
#Grm stain - 80% positive in gram-positive infxn; less sens in gram-negative
#Cell count with dif - &gt;50,000-150,000; PMN &gt; 90%
 
=== Treatment ===
 
#PCN-ase resistant synthetic PCN:
##Nafcillin 1-2g
##Cefazolin 1-2g
 
AND
 
#3rd gen ceph
 
OR
 
Vanc^
 
^new evidence suggests significantly increased rate of MRSA septic arthritis
 
^^cell counts are as low as 20,000 in MRSA Cx + synovial fluid
 
== Treatment ==
 
#drainage of the joint
#IV Antibiotics
#generally Oxacillin or Nafcillin with a cephalosporin (ceftriaxone, feotaxme, ceftizoxime) will cover
#add vancomycin if you suspect MRSA
#in IVDA patients use IV aminoglycoside + antipseudomonal cephalosporin
#patients with prosthetic joints are at higher risk of MRSA, MRSE, Enterobacteriaceae, and Pseudomonas
#consider gonococcal infection in young sexually active patients (treat with ceftriaxone)
#Open drainage and lavage in the OR
 
== Disposition ==
 
*All patients should be admitted with Ortho consult and continued on IV antibiotics
 
== See Also ==
 
*[[Arthrocentesis]]
*[[Monoarticular Arthritis]]
*[[Septic Arthritis (Hip)]]
*[[Septic Arthritis (Peds)]]
 
== Source ==
 
http://emprocedures.com/arthrocentesis/analysis.htmEmedicine
 
[[Category:ID]] [[Category:Ortho]]

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

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

See Also

References

  1. ↑ Mathews CJ, et al. Bacterial septic arthritis in adults. Lancet. 2010;375(9717):846-855. PMID 20206778.
  2. ↑ 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.
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