Diagnosis and management of acute osteoarticular infections in children

Question 1

Definition of osteomyelitis

Answer 1

inflammation of bone and bone marrow due to infection with microbial pathogen

Question 2

Acute osteomyelitis definition

Answer 2

• symptoms <2 weeks traditionally

* Outcomes similar in patients with symptoms up to 4 weeks

Question 3

Chronic osteomyelitis

Answer 3

symptoms > 1 mo where avascular bone (sequestrum) alone or surrounded by new bone (involucrum) is present (Brodies’ abscess)

Question 4

Organisms for SA & osteomyelitis

Answer 4

Staph aureus, Kingella king, S pneumonias, S pyogenes

Kingella
* dominant pathogen in children < 4 years with SA +/- AO

H flu if <4 yrs and unimmunized or area with high prevalence

Question 5

congenital syphilis presentation?

Answer 5

present with pseuoparalysis due to painful periostitis, osteitis, lytic lesions in metaphysis of long bones

Question 6

What makes the AO/SA probability low?

Answer 6

Normal or low CRP

Question 7

When do ESR/CRP peak in AO and osteo?

Answer 7

day 2 presentation

95% sensitivity

Question 8

What is the most sensitive and specific noninvasive test for AO?

What is earliest finding?

Answer 8

MRI

Earliest finding of AO: bone marrow edema

Question 9

What is the gold standard for assessment of osteomyelitis?

Answer 9

Bone specimen (biopsy)

Question 10

When should bone scan be used for osteo?

Answer 10

sensitivity - 80%, but early on can be false negative
Lower specificity than MRI
* Location - metaphysis supportive, diaphysis suggestive of other etiology
* when multifocalsites of infection are suspected, nuclear imaging may be a useful initial test

Question 11

What is the gold standard for assessment of septic arthritis?

Answer 11

• Joint aspiration

Question 12

Empiric antibiotics for OA/SA?

Answer 12

• cefazolin 100 - 150 mg/kg/day divided q6-8h for MSSA and K kingae
• K kingae resistant to clinda, vanco, clox

H flu
 cover if < 4 years and unimmunized or live in area of higher prevalence
 cefuroxime 150 mg/kg/day divided q8h

• MRSA
  
  • consider if high prevalence in community or known carrier
  • add vanco empirically if cultures will be available because bone biopsied or joint aspirated

Question 13

Antibiotics for H flu in OA/SA?

Answer 13

• cover if < 4 years and unimmunized or live in area of higher prevalence
• cefuroxime 150 mg/kg/day divided q8h

Question 14

if OA/SA fail to improve clinically within first few days of treatment?

Answer 14

repeat imaging and reconsider debridement surgery

Question 15

Contraindications to oral therapy of OA/SA?

Answer 15

• expected poor medication compliance or follow-up
• malabsorption
• slow clinical resolution of infection

Question 16

Transition to oral therapy for OA/SA?

Answer 16

• uncomplicated AO - afebrile, clinical improvement after 3-7 days IV therapy
• lower extremity: should weight-bear
• upper extremity: only mild pain with use
• CRP level: exact level unclear
  
  • 50% decrease over 4 day period
  • or level between 20-30 mg/L

If bacteremic: recommendations are regardless of whether blood cultures were positive and always assume a positive clinical response

Question 17

Duration of antibiotic therapy of AO/SA?

Answer 17

• Total duration for uncomplicated AO and SA: 21-28 days

* if SA of hip —> 4-6 weeks

Question 18

Follow up of OA/SA?

When is ortho FU needed?

When do you do Xray?

Answer 18

• document normal CRP
• routine radiographs only indicated if growht plate involved or large lytic lesion initially
• sclerosis at end of therapy
• ortho follow up if infection involves growht plate or adjacent epiphyseal or metaphyseal region