B6.007 Prework 1 Approach to Arthritis

Question 1

differential for monoarticular arthritis

Answer 1

trauma/ mechanical derangement
infection
crystalline arthritis- gout and pseudogout
hemarthrosis

Question 2

crystals in gout

Answer 2

monosodium urate

Question 3

crystals in pseudogout

Answer 3

calcium pyrophosphate

Question 4

what people more commonly present with hemarthrosis?

Answer 4

hemophiliacs

Question 5

differential for oligoarticular arthritis

Answer 5

crystalline

inflammatory (psoriatic, reactive, arthritis with IBD)

Question 6

tests typically performed on synovial fluid

Answer 6

WBC (2000 cutoff for inflammatory, 50000 for infection)
gram stain
bacterial culture
crystal analysis

Question 7

osteoarthritis findings on xray of IP joints in hands

Answer 7

asymmetric joint space narrowing
subchondral sclerosis (bright white at edges)
osteophyte formation

Question 8

RA findings on xray of IP joints in hands

Answer 8

marginal erosions
no osteophytes
periarticular osteopenia

Question 9

why do you see marginal erosions in RA?

Answer 9

pannus (inflammatory layer of tissue) has access to bone in marginal region

Question 10

classic first location of osteoarthritis

Answer 10

CMC joint (base of thumb at wrist level)
due to gripping motion

Question 11

signs of erosive osteoarthritis

Answer 11

central erosions (gull sign)
subchondral sclerosis
osteophytes
subchondral cysts
MCPs spared

Question 12

what is a charcot joint?

Answer 12

destruction of joint architecture due to neuropathic arthropathy
can be painless

Question 13

how does a charcot joint form?

Answer 13

loss of proprioception leads to ultimate instability in joint

Question 14

basic mechanism of corticosteroids in arthritis

Answer 14

inhibit phospholipase A2

Question 15

do you use corticosteroids in osteoarthritis?

Answer 15

no, not systemic

many side effects without a benefit

Question 16

basic mechanism of NSAIDs in arthritis

Answer 16

inhibit COX enzymes

wont prevent damage, but used in treatment of many arthritic conditions

Question 17

basic mechanism of methotrexate Iin RA treatment

Answer 17

low dose for RA treatment
polyglutamated form inhibits AICAR transformylase leading to accumulation of adenosine (anti-inflammatory effects)
also inhibits DHF reductase interfering w purine/pyrimidine synthesis (cancer treatment)