Osteomyelitis Flashcards
what is it characterised by
bone necrosis and reactive bone formation
describe the process
Bacteria lodge in metaphyseal blood vessels and set up an inflammatory reaction in the medullary canal, which spreads through the cortex, elevates the periosteum and may spread locally into an adjacent joint, causing septic arthritis, or into blood vessels causing bacteremia or septicemia
sequestrum
interference with blood supply leads to bone death and formation of sequestrum
once this is present, antibiotics alone will not cure the infection
involcurum
periosteum lays down a new shell of bone
why is s aureus particularly difficult to eradicate
can infect osteocytes intracellularly
who does an acute osteomyelitis in the absence of recent surgery usually occur in
children, and IC adults
osteomyelitis in children
metaphyses of long bones have tortuous blood vessels with sluggish flow - accumulation of bacteria and infection spreading towards epiphysis
in neonates and infants certain metaphyses are intra-articular - infection can spread into joint causing septic arthritis
what is different about infants periosteum
thicker and loosely applied - abscess can extend widely along sub periosteal space
brodie’s abscess
form of localised subacute or chronic osteomyelitis with a more insidious onset
found in children
central cavity containing pus, surrounded by reactive bone sclerosis
how does chronic osteomyelitis develop
from an untreated acute osteomyelitis
what may chronic osteomyelitis be associated with
involucrum/sequestrum
where does chronic osteomyelitis tend to occur in adults
axial skeleton (pelvis, spine) or intervertebral disc
how can chronic osteomyelitis present
can be suppressed with antibiotics and lay dormant for years before reactivating
where does TB cause chronic osteomyelitis
often spine through haematogenous spread from lung infection
diffuse osteomyelitis
resulting skeletal instability eg infected non union
superficial osteomyelitis
outer surface of bone
sickle cell anaemia patients with osteomyelitis
causative organisms
s aureus
also salmonella
who does h influenzae cause osteomyelitis in
children
treatment of chronic osteomyelitis
surgery - remove sequestrum and debride
antibiotics alone not enough
fixation of bone if instability
who is at particular risk of osteomyelitis of the spine
poorly controlled diabetics, IV drug abusers and other IC patients
complication of spinal surgery
how do patients with osteomyelitis in the spine present
insidious onset of back pain, constant and unremitting
paraspinal muscle spasm and tenderness
fever and systemic upset
severe cases - neurological deficit
vertebral end plates weaken, and may eventually collapse
