Joint Disorder

1. In a patient presenting with joint pain, distinguish benign from serious pathology (e.g., sarcoma, septic joint):
   1. By taking pertinent history
   2. By investigating in a timely and appropriate manner (e.g., aspirate, blood work, an X-ray examination).
2. In a patient presenting with non-specific musculoskeletal pain, make a specific rheumatologic diagnosis when one is evident through history, physical examination, and investigations. (e.g., gout, fibromyalgia, monoarthropathy vs. polyarthropathy).
3. In a patient presenting with a monoarthropathy, rule out infectious causes. (e.g., sexually transmitted diseases).
4. In patients presenting with musculoskeletal pain, include referred and visceral sources of pain in the differential diagnosis. (e.g., angina, slipped capital epiphysis presenting as knee pain, neuropathic pain).
5. Clinically diagnose ligamentous injuries. Do NOT do an X-ray examination.
6. In a patient presenting with joint pain, include systemic conditions in the differential diagnosis (e.g., Wegener’s granulomatosis, lupus, ulcerative colitis).
7. In patients with a diagnosed rheumatologic condition:
   1. Actively inquire about pre-existing co-morbid conditions that may modify the treatment plan.
   2. Choose the appropriate treatment plan (e.g., no nonsteroidal anti-inflammatory drugs in patients with renal failure or peptic ulcer disease).
8. In assessing patients with a diagnosed rheumatologic condition, search for disease-related complications (e.g., iritis).
9. In patients experiencing musculoskeletal pain:
   1. Actively inquire about the impact of the pain on daily life.
   2. Treat with appropriate doses of analgesics.
   3. Arrange for community resources and aids (e.g., splints, cane), if necessary.
10. In patients with rheumatoid arthritis, start treatment with disease-modifying agents within an appropriate time interval.

See fibromyalgia, gout, rheumatoid arthritis.

Approach to Monoarthritis

Differentiate joint vs. soft tissue

• Arthritis: Pain on ROM, decreased ROM, swelling, erythema
• Soft tissue: ROM preserved, tendernes over bursae, tendons, or ligaments

DDx

• Trauma
  • Hemarthrosis is associated with intraarticular fractures, dislocations, ligamentous injury
• Infection (Septic arthritis)
  • Gonoccocal can present as purulent arthritis or a triad of tenosynovitis, vesiculopustular skin lesions, and polyarthralgias
  • Non gonococcal bacterial infections should be suspected in IVDU, immunocompromised, prosthetic joint
  • Other: Mycobacterial, fungal, Lyme
• Crystal-induced arthritis
  • Gout (monosodium urate crystal)
  • Pseudogout (CPPD)
• Osteoarthritis
• Systemic
  • Seronegative spondyloarthritis (suspect in enthesitis, dactylitis, conjunctivitis/uveitis, psoriasis)
    • Reactive arthritis
    • Psoriatic arthritis
    • Inflammatory bowel disease-associated arthritis
  • Sarcoid periarthritis
  • Rheumatoid arthritis
  • Myelodysplastic and leukemic disorders
• Mechanical derangement
• Neoplasm

History

• Red Flags
  • Hot/swollen joints
  • Constitutional symptoms (high-grade fever, weight loss, malaise)
  • Morning stiffness >30 minutes
  • Night pain
  • Weakness
  • Neurological (burning pain, numbness, or paresthesia)
• Joint pain (OPQRST)
• Prior joint pain/similar episodes
• Systemic arthritis (morning stiffness>1h)
• Trauma
• Travel (Lyme)
• Seronegative spondyloarthritis (GI/GU complaints)
• Family history
• PMH (immunosuppression)
• Habits (IVDU, STI risk)

Physical Exam

• Vitals, temperature (high-grade fever)
• Soft tissue swelling, warm, effusion
• Passive/Active ROM
• Extraarticular
  • Tophi
  • Skin changes (Psoriasis, Malar rash, Erythema nodosum)
  • Eye involvement

Investigation

• Imaging (XR, US, CT, MRI)
  • Consider avoiding imaging in absence of trauma or focal bone pain
• Joint aspiration
  • Gross appearance
  • Crystal analysis
  • White cell count and differential
    • <2,000/mm3 usually non-inflammatory
    • >20,000 suspect septic arthritis
  • Gram stain and Culture
• Consider Labs
  • CBC
  • LFT
  • ESR/CRP
  • ANA, RF, Anti-CCP
  • (HLA)-B27
  • Coags (in hemarthrosis)