Lec 14 Bone Infections Flashcards
What is osteomyelitis?
inflammation of bone and marrow due to infection
What are 4 types of osteomyelitis?
- pyogenic osteomyelitis
- tuberculous osteomyelitis
- syphilitic osteomyelitis
- miscellaneous
What are 3 mech by which organisms reach the bone?
- hematogenous spread
- direct extension from contiguous site
- direct implantation
What are most common locations of pyogenic osteomyelitis?
long bones and vertebral bodies
What is most common organism responsible for pyogenic osteomyelitis?
staph aureus
What 2 organisms cause neonatal osteomyelitis?
- H influenzae
- group B strep
What organisms cause pyogenic osteomyelitis in pats with GU infection or IV drug abuse?
gram negative organisms –> E coli, pseudomonas, klebsiella
Where in the bone do most infections occur in kids and adolescents?
occur at metaphysis –> growth plate blocks vessels from being in contact w/ epiphyseal vessels
What are symptoms of osteomyelitis?
- high fever
- localized pain and swelling
- high WBC
- high ESR
What are most frequent sites of osteomyelitis in kids?
metaphyses of distal femur, proximal tibia, proximal humerus, and distal radius
== areas of rapid growth
In adults what is most frequent site of osteomyelitis?
subchondral region of long bones, diaphysis, spine, small bones of feet
Who gets hematogenous osteomyelitis?
pts with chronic diseases or drug addicts
Who get spinal osteomyelitis?
pts with GU infection
Who gets hematogenous osteomyelitis of the small bones of feet?
pts with peripheral vascular insufficiency, diabetes
Where do drug addicts usually have focus of infection?
spine or pelvis –> carries from skin or from unclean hypodermic needles
What happens once bacteria proliferates in metaphysis?
have bone necrosis and spread of infection to periosteum –> subperiosteal abscess formation –> impaired blood supply and get segmented bone necrosis
What is the sequestrum?
dead piece of bone
What is the involucrum?
sleeve of reactive bone around dead piece
What radiographic changes do you see in osteomyelitis?
- lytic focus of bone destruction w/ peripheral zone of sclerosis and periosteal reaction
hot spots on bone scan
What is differential diagnosis for osteomyelitis?
think round cell tumor
What is a brodie abscess?
small interosseous abscess that involves cortex and is surrounded by reactive bone
What are rare complications of osteomyelitis?
fractures, sepsis, squamous cell carcinoma, osteosarcoma
What is chronic recurrent multifocal osteomyelitis?
idiopathic inflammatory disorder of bone in kids and young adults
multifocal; non-pyogenic
have pain, tenderness, swelling
mostly effects lower extremities, metaphysis; medial clavicle
symmetric bilateral lesions; sclerosis
What are some pathologic conditions associated w/ chronic recurrent multifocal osteomyelitis?
- psoriasis
- acne fulminans
- palmoplantar pustulosis
What is tuberculous osteomyelitis?
commonly in spine; solitary bone infection [except multifocal in AIDS]
usually blood-borne from focus in lung or intestine
What is pathology of tuberculous osteomyelitis?
have necrotic tissue w/ white cheesy appearance
typical tubercle contains central necrosis surrounded by epithelioid histiocytes, multi-nucleated giant cells, lymphocytes
What is skeletal syphilis?
in acquired syphilis –> part of tertiary stage
in congenital –> bone lesions appear 4th month of gestation and fully developed at birth; localize in areas of active endochondral ossification
What are pathologic findings in skeletal syphilis?
- granulation tissue w/ plasma cells and necrotic bone
- gummata composed of necrotic material w/ granulomatous response
- spirochetes seen w/ silver warthin starry stain
What is saber shin?
anterior curvature of tibia with excessive bone deposition anteriorly = sign of skeletal syphilis
What is infectious arthritis?
infection of joint space; can cause rapid destruction of joint in days
What are signs of septic arthritis?
usually single joint –> knee > hip > shoulder > elbow
What is tuberculous arthritis?
synovium shows caseous granulomas; seen in hip, knee, ankle
Who gets fungal infection of bone/joint?
young immune compromised
usually blasto, crypto, aspergillus, candida; often from focus in lungs
What kind of parasite causes bone infection?
echinococcus granulosus = hydatid cyst –> need to resect
