Osteomyelitis

Question 1

how does osteomyelitis occur?

Answer 1

vertebral bodies - hematologenous spread or recent surgery in area

contiguous spread osteomyelitis may arise from direct contamination (fracture, joint replacement, orthopic implant)

Wounds - pressure sores, diabetic foot ulcers

adjacent soft tissue infection

Question 2

clinical presentation of osteomyelitis

Answer 2

subacute or chronic pain over affected region of bone

spontaneous opening of wound accompanied by drainage (sinus tracts) are a late manifestation of infection

Question 3

when to consider an underlying osteomyelitis infection?

Answer 3

chronic wounds like pressure ulcers do not respond to appropriate therapy

Question 4

what do we NOT see in presentation of osteomyelitis

Answer 4

rare to see fever, or other systemic symptoms of infection

Question 5

labs of osteomyelitis

Answer 5

no specific testing can be done

ESR/CRP are elevated and this is suggestive and raises pre-test probability of infection

won’t see any WBC elevation unless in acute hematogenous osteomyelitis

Question 6

1st imaging study to order for suspected osteomyelitis

Answer 6

XR
- easy and cheap and quick

if negative doesn’t rule out possibility of infection

Question 7

Test of choice for diagnosis of osteomyelitis

Answer 7

MRI WITH AND WITHOUT contrast is gold standard

if cannot obtain MRI, get CT with IV contrast

can use nuclear medicine studies which are less sensitive or specific for osteomyelitis

Question 8

bone biopsy is necessary for osteomyelitis because

Answer 8

confirms the presence of pathogen and maximizes the chance that chosen antibiotic regimen will work to treat it

Question 9

when to get osteomyelitis bone biopsy?

Answer 9

at time of surgery or by image guided biopsy

Question 10

when can we forego bone biopsy in osteomyelitis

Answer 10

when pts also have positive blood cultures

possible exception to this is IVDA as they have frequent bacteremia and the organism in blood culture may not represent organism in the bone

Question 11

in culture negative disease of bone biopsy (bone biopsy didn’t reveal a species), what testing can we do to figure out the bacteria causing osteomyelitis?

Answer 11

get a nucleic acid amplification test of bone biopsy and look for possible causative organism but this technique will not tell you the susceptbilities

Question 12

Treatment duration of osteomyelitis is :

Answer 12

IV antibiotics for 4-6 weeks

Question 13

Golden rule about osteomyelitis and starting antibiotics

Answer 13

unless there’s systemic signs of sepsis or concomittant soft tissue infection or bacteremia present, you should hold off on empiric antibiotics until bone biopsy is obtained for culture data

hate ER docs who start empiric antibiotics

Question 14

which antibiotics are preferred for osteomyelitis

Answer 14

IV over PO but some like fluoroquinolones have good bone penetration because they have high bioavailable with oral agents

Question 15

when to consider osteomyelitis when there is a diabetic ulcer?

Answer 15

when the diabetic foot ulcer is deep (presence of exposed bone)

large in diameter >2cm

chronic (nonhealing after 6 weeks of standard care)

2/3 of pts with diabetic osteomyelitis WILL NOT have elevation in ESR/CRP

Question 16

what test can you do to check if there’s osteomyelitis on physical exam:

Answer 16

sterile probe to bone test and look for contact with a hard or gritty surface representing bone or joint capsule

if presence of pus or high positive predictive value of probe to bone test is high

non infected ulcer - negative predictive value is high

Question 17

all pts who have a new diabetic foot infection should get

Answer 17

XR to look for

• new bony abnormalities
• soft tissue gas
• foreign bodies

Question 18

what bacteria causes most diabetic foot infections?

Answer 18

staph and strep make up 70%

25% have gram negative bacteria

infections can be polymicrobial

Question 19

duration of treatment for diabetic osteomyelitis?

Answer 19

IV or PO 4-6 weeks but may need longer course if there’s signs of residual necrotic bone

Question 20

indications for amputation of diabetic foot osteomyelitis:

Answer 20

• persistent sepsis
• inability to tolerate antibiotic therapy
• progressive bone destruction despite appropriate therapy
• bone destruction that compromises the mechanical integrity of the foot.

-pt may choose amputation over prolonged antibiotic therapy. NO need for antibiotics after amputation

Question 21

risk factors for vertebral osteomyelitis:

Answer 21

older age
immunocompromised 
indwelling catheters
HD
IVDA

Question 22

how does osteomyelitis of the vertebrae happen?

Answer 22

have infection that occurs in the intervertebral disc space causing spondylodiskitis and then see adjacent spread to the vertebral bodies.

usually its the lumbar spine, then the thoracic then cervical spine

Question 23

presentation of vertebral osteomyelitis:

Answer 23

new onset back or neck pain or progressive worsening of chronic pain that is unresponsive to conservative treatment

esp if high levels or ESR/CRP and unexplained neurological symptoms

Question 24

best diagnostic study for diagnosing vertebral ostemyelitis

Answer 24

MRI

also need to get blood cultures
test for TB for those who are at risk

Brucella serological test is diagnostic without need for biopsy

Question 25

who needs to get a bone biopsy for vertebral osteomyelitis

Answer 25

if it’s negative blood culture and there’s a spot on MRI concerning for osteomyelitis

if first biopsy is non diagnostic need to get a second biopsy

Question 26

Treatment for vertebral osteomyelitis is

Answer 26

6 weeks

Question 27

osteomyelitis in a sickle cell patient and empiric coverage:

Answer 27

samonella coverage and staph coverage

vancomycin and ciprofloxacin

Question 28

hematogenous osteomyelitis is more common in

Answer 28

children and sickle cell pts and IVDA

occurs in axial skeleteon and pelvic and less commonly in long bones like tibia

can see destruction on XR.