Seronegative Arthritis Flashcards
define poly-arthritis
inflammation of more than 4 joints
define oligoarthritis
inflammation of 2 or 3 joints
mono is jusy one
what is acute poly-arthritis
less than 6 weeks infection related: bacterial, viral, post-infectious reactive early autoimmune metabolic: crystal-induced arthritis) neoplastic: leukemia
what is chronic poly-arthritis
more than 6 weeks
infection: hep c
immune: RA, seronegative spondyloarthopathy, connective tissue diseases
metabolic: crystal-induced arthritis
degenerative: OA
what are features of spondyloarthropathies
rheumatoid factor & ANA neg axial arthritis (sacroiliitis, spondylitis) peripheral (asymmetric, LE > UE) oligo/poly-arthritis, large joints young at onset (<40) HLA-B27 ENTHESITIS may/may not have high ESR/CRP
what is enthesitis
inflammation at fibrocartilage insertionsof tendons, fascia or ligaments into bone
describe ankylosing spondylitis (AS)
symmetrical sacroiliitis ascends from lumbar to cervical progressive bony fusion M>F onset late teen - early 20s high in Native Americans, low in black
clinical features of AS
alternating buttock pain (SI joints) morning stiffness of back (>1hr) worse w rest, improve w exercise pain >3mo patient <40yr old 1/3 w peripheral joint involvement
PE for AS
tender SI joints/spine/entheses
decreased ROM in all planes
lumbar: reduced Schober’s test)
cervical: increased occiput-to-wall distance
decreased chest expansion
question mark posture
(decreased lumbar lordosis, increased thoracic kyphosis, decreased cervical lordosis)
describe Schober’s test
mark dimples of venus
mark 10cm above
measure between marks after bending down
should increase more than 15cm
describe occiput-to-wall
patient stand close to wall
should be 0 distance between back of head to wall
XR features of AS
sacroiliitis: erosion and sclerosis of joint margins, late (bony fusion, loss of sclerosis)
squaring of vertebral bodies (not concave)
symmetrical syndesmophytes (ossification of longitudinal spinal ligaments)
sclerosis and fusion of facet joints
osteoporosis
end stage: bamboo spine
extra-articular features of AS
Enthesitis (insertion of achilles, plantar fascia)
iritis (blurriness, scarring, vision loss)
cardiac involvement
pulmonary fibrosis
pathogenesis of AS
HLA-B27 codes for class I MHC
believed to bind arthritogenic peptides from gut bacteria
bacterial peptides resemble self-antigens (molecular mimicry) –> T-cells cross react and initiate inflammation
need both bowel inflammation and HLA gene
is HLA-B27 a good screening test?
no
