infection of bones and joints Flashcards
how does hematogenous infection become necrotic?
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
three types of joint drainage techniques
needle drainage, arthroscopic drainage, surgical drainage
usual antibiotics course?
4-6 weeks of high dose IV
another name for joint infection
septic arthritis
what kind of infection is osteomyelitis?
progressive, inflammatory, and usually bacterial destruction of bone and formation of new bone
CRP and ESR
c reactive protein - produced by liver in inflammation erythrocyte sedimentation rate **both are indicators of inflammation when they increase
best imaging test for osteomyelitis?
MRI - 90% sensitivity
cat and dog bites can introduce what infectious organism
pasteurella
risk factors of joint infection?
other joint diseases or any abnormal joint finding/history prosthetics, IV drug use, alcoholism, diabetes, ulcers, immune suppression
treatment of septic arthritis
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
first sign of osteomyelitis?
periosteum elevation wont have signs for atleast 2 weeks
1 cause of osteomyelitis and joint infection
staph aureus
area of slow blood flow in bones?
mataphyseal loops
ways to diagnose osteomyelitis?
MRI, probe to bone test, blood culture but definitive diagnosis via BONE BIOPSY!
how does joint infection presentation differ from osteomyelitis?
usually it will be visible something is wrong and leukocytosis is common!
three ways infection can get into bone:
spread from other infection direct innoculation from trauma or surgery hematogenously (through blood)
what is sequestrum and what is involucrum?
sequestrum = necrotic center involucrum is surrounding new bone
how to treat after necrosis has started?
you have to do surgery debridement PLUS antibiotics…not just abx alone
joint infection presentation
chills and fever inflammation, red, swollen, painful decreased mobility, visibly infected usually just one joint –> most of the time knee but others too
sunburst appearance
elevation of periosteum
symptoms of bone infection
fevers chills night sweats lethargy tenderness, swelling, erythema draining sinus can be subtle and not diagnosed right away
three ways for joints to get infected?
hematogenous direct (trauma, bite) corticosteroid injections
what ensures binding of staph aurreus to collagen in infection?
collagen adhesin protein
three reasons staph aureus is so common in osteomyelitis?
- 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
lab finding of bone infection
often no leukocytosis, and sometime elevated ESR and CRP but not very helpful
when can you treat with antibiotics alone? how to treat all other cases?
acute (no necrosis), terminal digits and vertebral osteo all others –> antibiotics AND surgical debridement
classic entry point of infection into metaphysis?
nutrient artery of metaphysis
where does bone infection settle most of the time in kids versus adults
kids - long bones adults – vertebral bodies
inflammation of bone due to infection
osteomyelitis
joint infection lab findings
leukocytosis elevated ESR and CRP wbc >50,000 50% below blood glucose
why is a superficial culture not helpful?
resident flora on skin could contaminate deeming test useless
