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 treatment Earlier 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 Infection Starts 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

Pathophysiology Gaps 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 joint Hip / Shoulder / Fibula / Proximal Humerus

Pathophysiology Role of Trauma Rabbit experiment IV injection of bacteria With # start in hematoma

Pathophysiology Role of growth plate Over 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

Diagnosis Pain Fever Lethargy Anorexia Neonate peudoparalysis NWB Failure 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 CRP More 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 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

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 reliable Acute phase reactants False sense of security 25% increased Mayo clinic 65% diff abnormal Acute phase reactants Change in plasma proteins d/t cytokines

Diagnosis ESR CRP 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 Soft tissue swelling 48hrs Sensitivity 43-75% Specificity 75-83% Soft tissue swelling 48hrs Periosteal reaction 5-7d Osteolysis 10d to 2 wks (need 50% bone loss)

Radiology 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

Radiology Gallium Indium Monoclonal antibodies 48 hrs to do Non specific Indium I131 leucocytes 24hrs to prepare Monoclonal antibodies Not proven to be better

Radiology MRI Marrow and soft tissue swelling Good in spine and pelvis Sensitivity 83-100% Specificity 75-100% PPV = Tc99 Marrow and soft tissue swelling Good in spine and pelvis

Radiology T1 Best for acute infection Gadolinium helps Changes similar to # Infarct Bruise Tumor Post surgical Sympathetic edema

Radiology CT Gas sequestrum

Treatment Mostly medical Timing !! 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

Treatment Antibiotic treatment Follow WBC / ESR/ CRP Parenteral / oral combinations Often empirical Serum level more important than route Follow WBC / ESR/ CRP Organism / sensitivity

Treatment Treatment Failure High 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 studies Follow CRP Shorter period of tx needed IV 5d / total 23 d tx Cephalosporin 150mg/kd/day

Treatment Neonates No studies, little evidence CRP / ESR not reliable Oral absorption not reliable Therefore IV neonates Cloxacillin

Treatment Longer treatment required Pelvis Vertebrae Diskitis Calcaneus

Treatment Surgical intervention Sx less frequent with newer antibiotic 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

Treatment Surgery Indicated Subperiosteal Abscess Soft Tissue abscess Bone Abscess Failure of clinical response to antibiotic Associated septic arthritis

Complications Infection Complications Antibiotic Complications Recurrence Chronic osteo Pathologic fracture Growth plate injury Antibiotic Complications Diarrhea N+V Rash Thrombocytopenia Neutropenia