Musculoskeletal Infections Flashcards
infection of skin, subcutaneous, fat, or connective tissue (soft tissue infection)
cellulitis
infection of bone (marrow spaces)
osteomyelitis
infection of joint (synovial tissue, articular surfaces)
septic arthritis
group of people prone to infections by unusual organisms at unusual sites
drug addicts
MC organism for musculoskeletal infections*
staph. aureus
MC route of dissemination for musculoskeletal infections
hematogenous
growth plates inhibit ONLY this route of dissemination
hematogenous
MC locations for musculoskeletal infections (KHASS)
- knee
- hip
- ankle (distal tibia)
- shoulder
- spine
two major categories of musculoskeletal infection
- suppurative (pus, staph)
2. non-suppurative (Tb)
bone marrow infection by pyogenic non-TB organism
suppurative osteomyelitis
clinical features of acute infection
1 edema 2 lymphadenopathy 3 warm skin 4 cellulitis 5 joint pain
4 radiographic stages of infection
- latent stage (1-10 days)
- early stage (days 10-21)
- middle stage (weeks)
- late stage (months)
symptoms of early stage infection
- spinal lesion
- ST swelling
- displaced lucent fat planes become mass like
- osteopenia
characteristics of middle stage infection
permeative or lytic moth-eaten destruction and periosteal response; solid, laminated, codman’s trianlge
characteristics of late stage infection
- cortical destruction
- draining sinus
- involucrum
- cloaca
- sequestrum
- sclerosis
- debris
- loss of joint space
- ankylosis
- chronic incomplete resolution
- immune deficient
chalky, white area representing isolated dead bone; cortical and medullar infarcts
sequestrum
chronic periosteal response. pus lifts the periosteum and causes new one formation that tries to wall off the infection.
involocrum
bony collar
involocrum
draining sinus, more common with chronic disease
cloaca
a rare complication of cloaca is to develop a squamous cell carcinoma with malignant transformation has been called
marjolin’s ulcer
localized, aborted form of suppurative osteomyelitis that has localized pain worse at night and relived by aspirin
brodie’s abscess formation
oval, elliptical or serpiginous radiolucency surrounded by reactive sclerosis mimics osteoid osteoma. located in distal tibia.
brodie’s abcess
seen in chronic osteomyelitis and reactive sclerosis
brodie’s abcess
prognosis of infection
- better detection and tx today
- require antibiotic mgmnt
infection of vertebral body
spondylitis
tear drop distance normally
9 - 11 mm
early radiographic features of spine infection
- rapid loss in disc space
- endplate destruction
- pre-vertebral ST swelling
upper limit size of the retro-tracheal interspace (RTI)
22mm
upper limit size of the retro-pharyngeal interspace (RPI)
7mm
water is white on which film
T2 weighted MRI
fat is white on which flim
T1 weighted MRI
MC cause of suppurative osteomyelitis
staph. aureus
both infections and tumors respect epiphyseal growth plates
FALSE: tumors respect the boundary but infections do not
disc space loss with endplate destruction is a classic example of
spine infection
risk groups for bone infection
- immunosupressed
- diabetic
- post surgical
- vascular insufficiency
- sickle celll anemia
- IV drug users
some organisms that cause bone infection and MC
- STAPH. AUREUS (90%)
- mycobacterium TB
- neisseria gonorrhea
- pseudomonas
- fungus
- strep. pyogenes
modes of infection
- trauma/post surgical
- UTI
- pneumonia
- skin infections
- open wound or cellulitis
- heel sticks in infants
routes of dissemination for bone infection
- HEMATOGENOUS (MC)
- direct extension
- direct implantation
- postoperative
growth plates inhibit which type of dissemination/spread
hematogenous; children affected less than adults or infants
study done sensitive to metabolic activity and increased vascular supply
bone scan
most important dx to consider when patient presents with unilateral sacroilitis
infection
exam needed if loss in disc space and endplate destruction
think infection so; MRI
osteomyelitis findings on an MRI
- decreased signal intensity T1
- increased signal intensity T2
*MC cause of infection-related death world wide “king of disease”
TB
MC type of TB
secondary form of Tb
MC location of TB in the spine
Spine TL junction
first radiographic finding of TB in an adult
earliest - anterior disc space narrowing.
phemster’s triad indicative of
TB septic arthritis
phemster’s triad (JaMS)
- juxtarticular osteoporosis
- marginal erosions
- slow joint space loss
type of TB found in spine, involving multiple levels with paraspinal cold abcesses, slower progression of jt destruction, poorer response to therapy
non-suppurative; as opposed to suppurative
destructive changes of EPs and bodies w acute kyphotic angulation
gibbus formation
TB associated with the spine
pott’s disease
Clinical findings associated with Tb
- positive Tb skin test 90-100%
- chest film (+) for granulomas in 50%
- wt loss, fever, chills, night sweats, tenderness in involved bones and jts
Radiographic findings of Tb similar to suppurative BUT…
- multiple level paraspinal cold abscesses w Ca (parallel psoas major m.)
- adult infxn typically starts in anterior endplate region
- disc space narrowing earliest radiographic finding
- vertebral collapse
- decreased T1, increased T2
- much slower and indolent
joint space loss and lytic destruction that crosses joint space indicate
septic arthritis
