OnlineMedEd - Rheumatology: Approach to Joint Pain

Question 1

When seeing a patient with joint pain, you should first ask _________________.

Answer 1

about timing and toxicity

Disorders that are acute and painful, red, and swollen: 
•Infection
• Crystalopathies 
•Trauma
•Reactive arthritis 

Disorders that are indolent/chronic:
•Non-inflammatory? Probably osteoarthritis
•Inflammatory? Assess number of joints involved (described in another card)

Question 2

How can number of joints involved in an inflammatory process help you evaluate possible diagnoses?

Answer 2

• If only one joint is inflamed, then infection, crystalopathy, or trauma is more likely.
• If more than one joint is involved, rheumatoid arthritis, lupus, Sjogren’s, psoriatic arthritis, spondylitis, or sclerosis are more likely.

Question 3

Arthrocentesis will show ____________________ in a septic joint.

Answer 3

(1) pus, (2) greater than 50,000 cells –very important, (3) positive culture, and (4) negative crystals

Question 4

Sometimes N. gonorrheae doesn’t show up on Gram stain. What should you do if you don’t see anything on Gram stain but suspect gonococcal infection?

Answer 4

Pass the sample through a nucleic acid amplification assay.

Question 5

In an arthrocentesis, the PMNs should account for about ______% of the cells aspirated.

Answer 5

25

Question 6

Describe what an arthrocentesis will show in an inflamed joint.

Answer 6

• Appearance: cloudy (that is, between the normal serous appearance and the pus of sepsis)
• Cells: between 2,000 and 50,000
• Gram stain: negative
• Crystals: positive for gout or pseudogout; negative for RA and the other non-crystal inflammatory disorders

Question 7

In general, the serologic tests for rheumatologic disorders are good for ______________.

Answer 7

ruling out rheumatologic disease, because they are sensitive but not specific

Question 8

List the common antibodies for rheumatologic diseases.

Answer 8

• ANA: lupus
• RF: rheumatoid arthritis
• Anti-CCP: rheumatoid arthritis
• Anti-dsDNA: lupus (in particular, lupus nephritis)
• Anti-histone: drug-induced lupus
• Anti-centromere: CREST scleroderma
• Anti-topoisomerase: systemic scleroderma
• Anti-smooth muscle: autoimmune hepatitis
• Anti-ro and la: Sjögren’s
• Anti-Jo-1: polymyositis and dermatomyositis
• Anti-mitochondrial: primary biliary cholangitis