Arthritis, Monoarticular

Basics

Description

  • Localized to 1 joint, not migratory
  • Aggravated by movement with erythema, swelling, and limited motion
  • Infectious (septic) arthritis: Rapidly destructive process causes significant morbidity:
    • Contiguous extension (cellulitis, osteomyelitis), hematogenous spread, direct inoculation
    • Predisposing factors:
      • Local pathology (inflammatory arthritis, trauma, prosthetic joint)
      • Immunosuppression
      • IV drug use
  • Crystal arthropathy:
    • Gout: Uric acid deposited within and around joints
    • Pseudogout: Calcium pyrophosphate
  • Various arthropathies:
    • Osteoarthritis, autoimmune disorders

Etiology

  • Infectious (septic):
    • Gram positives: Streptococcus/Staphylococcus (80%)
    • Some associations:
      • Staphylococcus aureus: Trauma, IV drug use
      • Neisseria gonorrhoeae (STI)
      • Salmonella (sickle cell) but most common causes in sickle cell Staphylococcus/Streptococcus
      • Mycobacterium marinum: Cleaning fish tank
      • Prosthetic joint: Polymicrobial
      • Less common: Fungal (chronic), spirochete (Lyme), viral (polyarticular), mycobacteria (TB)
  • Crystal arthropathy:
    • Gout: Uric acid overproduction, underexcretion
    • Pseudogout: Calcium pyrophosphate:
      • More common in elderly with DJD
  • Inflammatory:
    • Rheumatologic, psoriatic, inflammatory bowel disease, reactive arthritis (Reiter’s)
  • Other conditions:
    • Osteoarthritis, overuse, overload (obesity)
    • Hemarthrosis (hemorrhagic disorders, ligamentous/meniscal injuries, dislocations, intraarticular fractures, anticoagulants)
    • Neuropathic disorders (Charcot joint)
    • Mycobacterial and fungal infections
    • Benign or malignant tumors within the synovium or localized soft tissues, leukemic arthritis
    • Foreign-body inflammation from direct inoculation of plant material (plant thorn synovitis)
    • Extrapulmonary manifestation of histoplasmosis or coccidioidomycosis

Pediatric Considerations

  • Infectious (septic) arthritis:
    • Low incidence, high morbidity, sepsis (8%)
    • Most common: S. aureus, hip > knee, 50% coexisting osteomyelitis
    • Present like adults: Joint swollen, painful, worsened with weight bearing, movement; constitutionally ill, limp
    • Aspiration, empiric treatment, admission
  • Inflammatory:
    • A diagnosis only after septic joint excluded
    • Other considerations same as adults + juvenile idiopathic arthritis
  • Other considerations to not overlook:
    • Salter–Harris epiphyseal plate fractures
    • Congenital hip dysplasia
    • Slipped capital femoral epiphysis (SCFE):
      • Overweight adolescents
    • Legg–Calve–Perthes:
      • Avascular necrosis femoral head
      • Age 4–9
    • Bleeding disorders, hemorrhage

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