Osteomyelitis in Children

Outline

• Age

• Incidence

• Etiology

• Pathophysiology

• Presentation

• Laboratory investigations

• Imaging

• Treatment

• Surgery

• Complications

• Summary

• Special Groups

Age / Incidence / Etiology

• 1/1000 – 1/ 20 000

• Male > Female

• Pre antibiotic era ……20-50% mortality

• Advances in treatment

– Earlier dx

– Antibiotic tx

– Surgery less delay

– Children better nourished

• Glasgow incidence decreased

• New Zealand……. Madri > Whites

• South Africa…….. Black > Whites

• Changing disease / Changing organism

• Seasonal Variation

• Nutritional status, climate, lifestyle

• H Flu

– Big cause 1970’s

– 1-4 yrs

– Now decreased due to vaccinations

– Kingella Kingae

– OM in older kids

– Septic Arthritis 1-3 yrs

– Neonates separate group

Pathophysiology

• Poorly defined

– Direct inoculation

– Hematogenous spread

– Local invasion

• Infection

– Starts in Metaphysis

• Arteriole Loop / Venous Lakes

– Spread via Volkman’s canal / Haversian system

– Endothelium Leaks

• Few phagocytes in Zone of Hypertrophy

– Highest incidence in fastest growing bone

– Tubular > Flat bones

• Gaps in endothelium metaphyseal vessel



• Bacteria pass



• Adhere to Type 1 collagen



• Increase pressure in bone/ decrease blood flow



• Bone infarction / Dead Bone (sequestrum)

• Spread via Volkman Canal



• Subperiosteal Pus



• Cortex breaks down



• May spread to joint

– Hip / Shoulder / Fibula / Proximal Humerus

• Role of Trauma

– Rabbit experiment

– IV injection of bacteria

– With # start in hematoma

• Role of growth plate

– Over 18/12

– Impermeable to spread

– Under 18/12 infection crosses growth plate

• 1st osteoblasts die

• Lymphocytes release osteoclast activating factor

• Hole in bone

Diagnosis

• Pain

– Neonate peudoparalysis

– NWB

– Failure to use limb

• Fever

• Lethargy

• Anorexia

• Swelling (neonates / older kids)

• Bloodwork

– CBC Diff

– ESR

– CRP

– Blood Culture

• WBC increased 30-40%

• Left Shift 65%

• ESR increased 91%……….24-36hrs

• CRP increased 97%…………4-6hrs

• CRP

– More rapid than ESR

– 2-4 hrs …..peak 72hrs

– 10-30x normal

– Systemic ds (trauma, tumor)

• Blood Culture

– + 30-60%

– Decreased with antibiotic

– Multiple cultures no significant increase in yield

– 48 hours to get most organisms

Diagnosis

• Pus aspiration

– 70% bone + cultures

– Septic arthritis

• Gram stain

• Lymphocyte count

• % polymorphs

– > 80 000 = Septic arthritis

– > 50 000 in some series

– 80 000 also in JRA

• Do blood and joint cultures

– One or other not always +ve in same pt

– Gram stain +ve 1/3 bone and joint aspirations

• Future looking for bacteria DNA / RNA

Lab Diagnosis

• WBC not reliable

– False sense of security

– 25% increased Mayo clinic

– 65% diff abnormal

• Acute phase reactants

– Change in plasma proteins d/t cytokines

• ESR

– Nonspecific acute phase reactant

– Depends on fibrinogen concentration

– Increased 48-72 hrs

– Increased in 90% of cases

– Not affected by antibiotic tx

• CRP

– Increased in 98% of cases

Radiology

• Plain xray

– Sensitivity 43-75%

– Specificity 75-83%

• Soft tissue swelling 48hrs

• Periosteal reaction 5-7d

• Osteolysis 10d to 2 wks

– (need 50% bone loss)

• Tc99

– 24-48hrs +ve

– Bone aspiration DOES NOT give false +ve

– Decreased uptake in early phase d/t increased pressure

– “cold” scan up to 100% PPV

• Gallium

– 48 hrs to do

– Non specific

• Indium

– I131 leucocytes

– 24hrs to prepare

• Monoclonal antibodies

– Not proven to be better

• MRI

– Sensitivity 83-100%

– Specificity 75-100%

– PPV = Tc99

• Marrow and soft tissue swelling

• Good in spine and pelvis

• T1

– Best for acute infection

– Gadolinium helps

– Changes similar to

• #

• Infarct

• Bruise

• Tumor

• Post surgical

• Sympathetic edema

• CT

– Gas

– sequestrum

Treatment

• Mostly medical

– Sx to improve local environment

– Remove infected devitalized bone

– Decompress abscess cavity

• Timing !!

– Early antibiotic before necrosis / pus then sx less likely to be needed

• Antibiotic treatment

– Parenteral / oral combinations

– Often empirical

– Serum level more important than route

• Follow WBC / ESR/ CRP

• Organism / sensitivity

• Treatment Failure

– High doses

– Poor oral absorption / compliance

– Inadequate monitoring of serum levels

– Delay in Sx

• Previously start IV

• Follow ESR to guide switch to oral

• Newer studies

• Follow CRP

– Shorter period of tx needed

– IV 5d / total 23 d tx

– Cephalosporin 150mg/kd/day

• Neonates

– No studies, little evidence

– CRP / ESR not reliable

– Oral absorption not reliable

– Therefore IV neonates

– Cloxacillin

• Longer treatment required

– Pelvis

– Vertebrae

– Diskitis

– Calcaneus

• Surgical intervention

– Controversial indications

– Hole in bone not always Sx

– If purulent aspirate Sx necessary

• Sx less frequent with newer antibiotic

– 22-83% earlier studies

– 8-43% recent studies

• Surgery Indicated

– Subperiosteal Abscess

– Soft Tissue abscess

– Bone Abscess

– Failure of clinical response to antibiotic

– Associated septic arthritis

Complications

• Infection Complications

– Recurrence

– Chronic osteo

– Pathologic fracture

– Growth plate injury

• Antibiotic Complications

– Diarrhea

– N+V

– Rash

– Thrombocytopenia

– Neutropenia

Dr. Robert Deane

Janeway