Septic arthritis
Background
- Inflammation of synovial membrane with purulent effusion into the joint capsule
- Knee most commonly involved in adults; hip most common in peds
- Most often seen in pts >65yr
- Most commonly bacterial (gonococcal vs nongonococcal)
Clinical Features
- Fever
- Warm, red, painful, swollen joint
- Decreased range of motion (even passively)
Diagnosis
- Arthrocentesis for synoval fluid
| Normal | Noninflammatory | Inflammatory | Septic | |
| Clarity | Transparent | Transparent | Cloudy | Cloudy |
| Color | Clear | Yellow | Yellow | Yellow |
| WBC | <200 | <200-2000 | 200-50,000 | >25,000 |
| PMN | <25% | <25% | >50% | >90% |
| Culture | Neg | Neg | Neg | >50% positive |
| Crystals | None | None | Multiple or none | None |
Work-Up
- Arthrocentesis with synovial fluid analysis
- CBC
- 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 > 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-->pustular -->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 - >50,000-150,000; PMN > 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
Source
http://emprocedures.com/arthrocentesis/analysis.htmEmedicine