infection of bones and joints

Question 1

how does hematogenous infection become necrotic?

Answer 1

enters via nutrient loop/metaphyseal loops –> bone destruction and abscess formation –> cortical bone doesnt expand so inflammation grows and tiny vessels get compressed –> increase in pressure –> necrosis /lifting of periosteum

Question 1

three types of joint drainage techniques

Answer 1

needle drainage, arthroscopic drainage, surgical drainage

Question 2

usual antibiotics course?

Answer 2

4-6 weeks of high dose IV

Question 2

another name for joint infection

Answer 2

septic arthritis

Question 3

what kind of infection is osteomyelitis?

Answer 3

progressive, inflammatory, and usually bacterial destruction of bone and formation of new bone

Question 4

CRP and ESR

Answer 4

c reactive protein - produced by liver in inflammation erythrocyte sedimentation rate **both are indicators of inflammation when they increase

Question 4

best imaging test for osteomyelitis?

Answer 4

MRI - 90% sensitivity

Question 5

cat and dog bites can introduce what infectious organism

Answer 5

pasteurella

Question 5

risk factors of joint infection?

Answer 5

other joint diseases or any abnormal joint finding/history prosthetics, IV drug use, alcoholism, diabetes, ulcers, immune suppression

Question 5

treatment of septic arthritis

Answer 5

antibiotics AND drainage drainage is the key - often need to repeat **lyme disease is an exception! no drainage septic arthritis is a MEDICAL EMERGENCY—even a day can lead to incredible damage! and increases morbidity

Question 6

first sign of osteomyelitis?

Answer 6

periosteum elevation wont have signs for atleast 2 weeks

Question 7

1 cause of osteomyelitis and joint infection

Answer 7

staph aureus

Question 8

area of slow blood flow in bones?

Answer 8

mataphyseal loops

Question 9

ways to diagnose osteomyelitis?

Answer 9

MRI, probe to bone test, blood culture but definitive diagnosis via BONE BIOPSY!

Question 10

how does joint infection presentation differ from osteomyelitis?

Answer 10

usually it will be visible something is wrong and leukocytosis is common!

Question 12

three ways infection can get into bone:

Answer 12

spread from other infection direct innoculation from trauma or surgery hematogenously (through blood)

Question 14

what is sequestrum and what is involucrum?

Answer 14

sequestrum = necrotic center involucrum is surrounding new bone

Question 15

how to treat after necrosis has started?

Answer 15

you have to do surgery debridement PLUS antibiotics…not just abx alone

Question 16

joint infection presentation

Answer 16

chills and fever inflammation, red, swollen, painful decreased mobility, visibly infected usually just one joint –> most of the time knee but others too

Question 17

sunburst appearance

Answer 17

elevation of periosteum

Question 19

symptoms of bone infection

Answer 19

fevers chills night sweats lethargy tenderness, swelling, erythema draining sinus can be subtle and not diagnosed right away

Question 21

three ways for joints to get infected?

Answer 21

hematogenous direct (trauma, bite) corticosteroid injections

Question 23

what ensures binding of staph aurreus to collagen in infection?

Answer 23

collagen adhesin protein

Question 24

three reasons staph aureus is so common in osteomyelitis?

Answer 24

1. resident flora on skin 2. collagen adhesin - ensures binding to collagen 3. biofilm formation via quorum sensing - matrix of sugar, protein and DNa that inhibits clearance by immune system and penetration of antibiotics

Question 25

lab finding of bone infection

Answer 25

often no leukocytosis, and sometime elevated ESR and CRP but not very helpful

Question 26

when can you treat with antibiotics alone? how to treat all other cases?

Answer 26

acute (no necrosis), terminal digits and vertebral osteo all others –> antibiotics AND surgical debridement

Question 27

classic entry point of infection into metaphysis?

Answer 27

nutrient artery of metaphysis

Question 28

where does bone infection settle most of the time in kids versus adults

Answer 28

kids - long bones adults – vertebral bodies

Question 29

inflammation of bone due to infection

Answer 29

osteomyelitis

Question 30

joint infection lab findings

Answer 30

leukocytosis elevated ESR and CRP wbc >50,000 50% below blood glucose

Question 31

why is a superficial culture not helpful?

Answer 31

resident flora on skin could contaminate deeming test useless