Quiz #5 Flashcards
what is osteomyelitis?
bone inflammation caused by infection
what bones are typically affected by osteomyelitis?
pelvis (from UTIs), or arm (from IV)
what can osteomyelitis lead to?
septicemia or septic infection of a joint
where does osteomyelitis tend to occur in children?
near growth plates of long bones
where does osteomyelitis tend to occur in adults?
lumbar spine (bc of proximity to bladder)
what is the etiology of osteomyelitis?
usually caused by staph aureus infection in acute osteomyelitis
binds to cartilage and releases toxins
what is exogenous osteomyelitis?
invasion of bone from outside (open fx, puncture wound)
absess can infect bone
what is the prognosis for exogenous osteomyelitis in pts with DM, vascular insufficiency, or who are immunocompromised?
poor
what is hematogenous osteomyelitis?
spread of organisms from pre-existing infections through blood
often UTI
who does acute osteomyelitis occur the most in?
children and boys
who does chronic osteomyelitis occur the most in?
adults and the immunocompromised
what in a radiograph will indicate osteomyelitis?
opacity of bone
what are the risk factors for osteomyelitis?
chronic illness, alcohol abuse, diabetes, malignant, malnutrition, renal/hepatic failure, MRSA, large doses of steroids or immunosuppressants
what are some additional risk factors for development of osteomyelitis?
calcaneal or sacral decubiti deeper than 3 mm or >2 cm ^2
SCI w/complete motor or sensory loss
slow healing post-op wound
what does a radiograph show with periprosthetic infection?
periosteal new bone formation, scattered foci of osteomyelitis, subchondral bone resporption (late finding)
what is the gold stand for periprosthetic infection testing?
intra operative cultures
how is periprosthetic infection managed from least to most severe?
irrigation and debridement w/component retention, one or two-stage exchange, antibiotic suppression, resection, arthrodesis (jt fusion), or amputation
what is usually the first cause of prosthetic failure?
mechanical loosening
what is usually the second cause of prosthetic failure?
infection
what is the initial stage of pathogenesis of osteomyelitis?
inflammatory response
vascular loop in growing bone
arterioles form loop and drain in medullary cavity w/o establishing a capillary bed
what is the long bone metaphysis pathogenesis of osteomyelitis?
bone is porous and allows exudate from the infection to speard easily
organism grows and forms pus
increased bone tension in rigid medullary cavity
puss forced in Haversian canals
bacteria proliferates unimpeded
what is the subperiosteal absess formation pathogenesis of osteomyelitis?
bone is denied blood supply and may cause necrosis
necrotic cells are a fertile bed for infectious agents to multiply
no sensory nerve endings in cancellous bone so the process progresses without pain
necrosis stimulates the periosteum to form new bone
what is the last phase of pathogenesis of osteomyelitis?
sheath of new bone (involucrum) forms around sequestrum of necrotic tissue
chronic stage
more common in children, more fx in adults
is the involucrum and sequestrum more common in children or adults?
children