-
3 key inflammatory cytokines
- Activated by PAMPs or DAMPs
- TNF (tumor necrosis factor)
- IFN (interferon)
- IL-1beta
-
regulatory mechs that protect against self-reactive Abs
- double signaling/costimulation
- regulatory T-cells
- apoptosis
-
Factors contributing to tolerance failure
- genetic susceptibility: altered cytokine production/response, altered apoptosis, autoantigen exposure
- microbial exposure, toxins, UV light
-
findings characteristic of arthritis
- joint swelling
- increased warmth and/or erythema
- joint tenderness to palpation
- joint effusion
- pain on passive range of motion of affected joint = most specific sign
-
indications for arthrocentesis
- (joint aspiration)
- rule out septic joint
- evaluate for crystal arthopathy
- determine whether an effusion is inflammatory/noninflammatory
- theraputic drainage (pain relief, remove damaging enzymes)
-
monoarticular arthritis
- usually acute inflammatory symptoms
- most common: septic arthritis, crystal arthropathy - present identically, must get synovial fluid
-
septic arthritis
- most monoarticular (80-90%)
- can be acute or chronic
- medical emergency: marker for underlying infection, >3d irrev joint damage
- nongonococcal: hematogenous, innoculation, adj tissue infection - usually Staph aureus gram +
- gonococcal: STD, purulent arthritis + effusion, blood and mucosal cultures +, synovial fliud -, tenosynovitis, skin lesions
-
crystal arthropathy: gout pathophysiology
- inflammatory response to urate crystals mediated by innate immune system
- increased production: increased cell turnover, intake of food, alcohol, mutations in metabolizing genes
- decreased excretion:
- acute/chronic renal failure
- drugs that interfere with excretion: thiazide diuretics most common
- diabetes: increased insulin levels can interfere with excretion
- genetic predisposition: polymorphisms in renal urate transporters
-
gout presentation
- hyperuricemia
- sudden onset of monoarthritis
- lasts 3-10d
- tenosynovitis and bursitis also common
- low grade fever, tophi, bony erosions
- urate crystals can cause nephropathy
- negatively birefingent needle-shaped crystals
- CPPD distinguished by postively birefringent rhomboid-shaped crystals
-
osteoarthritis
- non-immune, mechanically-induced (altered joint loading)
- most common, 13.9% >25yr, 33.6% >65yr
- joint pain relieved by rest
- stiffness <30min
- decreased range of motion & crepitus
- tenderness to palpation w/o swelling
-
Rheumatoid Arthritis
- symmetric inflammatory polyarthritis, small joints of the hands, 0.1-1.1%, women @ 2-3x risk
- good outcomes w/early treatment
- autoimmune, cigarette smoking incr. risk for ppl w/HLA-DRB1 allele
- pannus formation, osteoclast activation
- insidious onset, granulomatous nodules, dry eyes -> keratitis
- C1/C2 impingement
- Felty's syndrome - splenomegaly/neutropenia
- Increased risk of B cell lymphoma
- Marginal bony erosions, joint space narrowing
- Anti-CCP: specific, not sensitive, cna be + before onset, incr erosions
-
seronegative spondyloarthropathies
- asymmetric oligoarticular peripheral arthritis
- sacroilitis/spondylitis (assoc. w/HLA-B27), enthesitis, extraskeletal involvement
- negative test for rheumatoid factor
- reactive, ankylosing spondylitis, psoriatic
-
ankylosing spondylitis (AS)
- bilateral symmetric sacroilitis
- enthesitis of spinal ligaments -> erosions -> syndesmophytes -> vertebral fusion
- 90% susceptibility due to genetics, more common in men
- stiffness >30min w/improvement upon activity
- pseudofractures
-
reactive arthritis
- type of seronegative spondyloarthropathy
- develops 1-4 wks post infection
- acute, asymmetric, chronic in 15-50%
- sacroilitis in 20%
- ulcers - oral/genital
- conjunctivitis, uveitis
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