Osteomyelitis in Children

Dr. Robert Deane

Janeway

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

Age / Incidence / Etiology

Advances in treatmentEarlier dx

Antibiotic tx

Surgery less delay

Children better nourished

Age / Incidence / Etiology

Glasgow incidence decreased

New Zealand……. Madri > Whites

South Africa…….. Black > Whites

Changing disease / Changing organism

Seasonal Variation

Nutritional status, climate, lifestyle

Age / Incidence / Etiology

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

Pathophysiology

InfectionStarts in Metaphysis

• Arteriole Loop / Venous Lakes

Spread via Volkman’s canal / Haversian system

Endothelium Leaks

Pathophysiology

Few phagocytes in Zone of Hypertrophy

Highest incidence in fastest growing bone

Tubular > Flat bones

PathophysiologyGaps in endothelium metaphyseal vessel

Bacteria pass

Adhere to Type 1 collagen

Increase pressure in bone/ decrease blood flow

Bone infarction / Dead Bone (sequestrum)

Pathophysiology

Spread via Volkman Canal

Subperiosteal Pus

Cortex breaks down

May spread to jointHip / Shoulder / Fibula / Proximal Humerus

Pathophysiology

Role of Trauma

Rabbit experiment

IV injection of bacteria

With # start in hematoma

Pathophysiology

Role of growth plateOver 18/12

Impermeable to spread

Under 18/12 infection crosses growth plate

Pathophysiology

Pathophysiology

1st osteoblasts die

Lymphocytes release osteoclast activating factor

Hole in bone

DiagnosisPain

Neonate peudoparalysisNWBFailure to use limb

Fever

Lethargy

Anorexia

Swelling (neonates / older kids)

Pathophysiology

Bloodwork

CBC Diff

ESR

CRP

Blood Culture

Pathophysiology

WBC increased 30-40%

Left Shift 65%

ESR increased 91%……….24-36hrs

CRP increased 97%…………4-6hrs

Pathophysiology

CRPMore rapid than ESR

2-4 hrs …..peak 72hrs

10-30x normal

Systemic ds (trauma, tumor)

Pathophysiology

Blood Culture

+ 30-60%

Decreased with antibiotic

Multiple cultures no significant increase in yield

48 hours to get most organisms

Diagnosis

Pus aspiration70% bone + culturesSeptic arthritis

• Gram stain• Lymphocyte count• % polymorphs

> 80 000 = Septic arthritis> 50 000 in some series80 000 also in JRA

Diagnosis

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 reliableFalse sense of security

25% increased Mayo clinic

65% diff abnormal

Acute phase reactantsChange in plasma proteins d/t cytokines

Diagnosis

ESRNonspecific acute phase reactant

Depends on fibrinogen concentration

Increased 48-72 hrs

Increased in 90% of cases

Not affected by antibiotic tx

CRPIncreased in 98% of cases

Radiology

Plain xraySensitivity 43-75%Specificity 75-83%

Soft tissue swelling 48hrsPeriosteal reaction 5-7dOsteolysis 10d to 2 wks

(need 50% bone loss)

Radiology

Tc9924-48hrs +ve

Bone aspiration DOES NOT give false +ve

Decreased uptake in early phase d/t increased pressure

“cold” scan up to 100% PPV

RadiologyGallium

48 hrs to do Non specific

IndiumI131 leucocytes24hrs to prepare

Monoclonal antibodiesNot proven to be better

Radiology

MRISensitivity 83-100%

Specificity 75-100%

PPV = Tc99

Marrow and soft tissue swelling

Good in spine and pelvis

Radiology

T1Best for acute infection

Gadolinium helps

Changes similar to• #

• Infarct

• Bruise

• Tumor

• Post surgical

• Sympathetic edema

Radiology

CTGas

sequestrum

Treatment

Mostly medicalSx to improve local environmentRemove infected devitalized boneDecompress abscess cavity

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

Treatment

Antibiotic treatmentParenteral / oral combinations

Often empirical

Serum level more important than route

Follow WBC / ESR/ CRP

Organism / sensitivity

Treatment

Treatment FailureHigh doses

Poor oral absorption / compliance

Inadequate monitoring of serum levels

Delay in Sx

Treatment

Previously start IV Follow ESR to guide switch to oral

Newer studiesFollow CRP

Shorter period of tx neededIV 5d / total 23 d txCephalosporin 150mg/kd/day

Treatment

NeonatesNo studies, little evidence

CRP / ESR not reliable

Oral absorption not reliable

Therefore IV neonates

Cloxacillin

Treatment

Longer treatment requiredPelvis

Vertebrae

Diskitis

Calcaneus

Treatment

Surgical interventionControversial indicationsHole in bone not always SxIf purulent aspirate Sx necessary

Sx less frequent with newer antibiotic22-83% earlier studies8-43% recent studies

Treatment

Surgery Indicated

Subperiosteal Abscess

Soft Tissue abscess

Bone Abscess

Failure of clinical response to antibiotic

Associated septic arthritis

ComplicationsInfection Complications

RecurrenceChronic osteoPathologic fractureGrowth plate injury

Antibiotic ComplicationsDiarrheaN+VRashThrombocytopeniaNeutropenia