Chronic Osteomyelitis in Children

DR. K.S.V. RaoMBBS, D.Orth, DNB( Ortho)

Khoula hospital,Muscat

1

Causes•Sequele of untreated acute hematogenous osteomyelitis

•Hematogenous spread from organisms of low virulence

•Spread of pyogenic infections from neighbouring tissues

•Open fractures

•Punctured wounds

•Complications of surgical procedures

Clinical Findings

• Fever, malaise, bone pain• Local tenderness / temperature ±• Sinus- discharge• Puckering /Granulation at mouth of sinus ±• Bony thickening- localised /length of diaphysis• Bony surface irregular• Wasting of muscles• Pathological fractures

Pathological Features• Hallmark is bone necrosis

• Exudation of PMNL, large no. of lymphocytes, histiocytes and plasma cells( occasionally )

• Formation of new bone (involucrum) from surviving periosteum & endosteum

• Involucrum- enveloping sheet of live bone with perforations (cloacae) for pus to drain to the exterior causing chronic sinus

• Proliferation of endosteal new bone causing obliteration of medullary canal

• Prostaglandin E production is increased many folds in infected bone causing bone resorption & sequestration formation

• Resorption is mediated by several cytokines –IL-1, IL-6, IL-11 & TNF α

Why Chronicity ?

• Negative charge on surface of devitalized bone promotes organism adherence and subsequent glycocalyx formation thereby preventing access to phagocytes & microbials.

• Bacteria enter the interior of the cell eluding host defense. Dead & dying osteoblast release viable S. Aureus causing persistence of infection & its flare up.

• Main infecting organism is likely to be the same organism as when present at the original attack even if a recurrent episode occurs years later!!

Sharrad .pediatric orthopedics & fractures vol-II

Labs• Leukocyte count- in acute OM, often normal

in chronic cases (elevated in only 35%)

• ESR– in both . after T/t- but increases immediately after operative debridement. Not a sensitive test to r/o acute or chronic OM, not reliable in compromised host/isolated findings ±

• CRP - in acute/chronic, faster than ESR, more sensitive. Favorable outcome if CRP decreases within 3 days of antibiotic treatment in acute cases, test weekly in acute & every ? 2 wks in chronic OM

• Monitoring drug toxicity Serum creatinine levels Liver function tests

• Nutritional status S. albumin level Total iron binding capacity

• Blood culture- yield approx. 60%• PCR• Culture & sensitivity- discharge/sinus• Deep bone biopsy- yield approx. 90% ( gold standard)

Microbiology

• Bone culture/deep bone biopsy are a must except in Cierny-Mader stage-1 where blood/ joint fluid cultures obviate need of biopsy

• Culture of samples from sinus tract is not reliable for predicting which organism will be isolated from infected bone

• Culture from sinus tract , purulent fluid, soft tissue & bone for aerobic /anaerobic/ fungal growth yielded organisms-

• >1 in 21/30• >3 in 11/30• 10 in 2/30• Same org. in 14/30( only in 47% )

• Recommendation is to send all 4 specimens –to identify as many organisms as possible.

• +ve co-relation has been found between S. aureus growth from sinus tract & that from bone culture.

Comparision of results of bacterial cultures from multiple sites in chronic OM

Patzakis et al JBJS, 1994;76A:664-666

Imaging

X-ray• Sequestrum• Involucrum• Cloacae• Cavity• Irregular bone thickening • Pathological fracture

CT Scan• To identify areas of necrotic bone/ sequestra• Help in establishing a surgical plan

MRI• High sensitivity & specificity for diagnosis• Localises abnormal bone marrow early• Can detect myositis, cellulitis, sinus tract

formation & soft tissue abscess• “Rim sign”-in chronic OM is high signal intensity

surrounding the focus of active disease

Radionuclide scan

• Used when diagnosis is ambiguous• Gauges extent of bone & soft tissue inflammation -99mTc - 67 Gallium citrate - 111 Indium labelled leukocytes-ideally for acute

OM.• MRI-is much more sensitive than nuclear studies .• During the 1st post-op year MRI can not accurately

distinguish infection from fibrovascular scar—COMBINED NUCLEAR MEDICINE STUDIES WERE FOUND TO BE MORE USEFUL DURING THIS PERIOD

18FDG PET Scan

Meta-analysis showed –Fluorodeoxyglucose positron emission tomography has the highest accuracy for confirming or excluding the diagnosis of Chr OM

“The Accuracy of Diagnostic Imaging for the Assessment of ChronicOsteomyelitis: A Systematic Review and Meta-Analysis”

The Journal of Bone and Joint Surgery (American). 2005;87:2464-2471.

Cierny-Mader Staging SystemCriteria DescriptionAnatomic type Stage 1 Medullary osteomyelitis Stage 2 Superficial osteomyelitis Stage 3 Localized osteomyelitis Stage 4 Diffuse osteomyelitisPhysiologic class A host Normal B host Bs Systemic compromise Bl Local compromise Bls Systemic and local compromiseC host Treatment worse than the disease

Radiologic Classification of Chronic Hematogenous

Osteomyelitis in Children

Henry Wynn Jones, FRCS (T&O), James W. Harrison, FRCS (T&O),Jeremy Bates, FCS (ECSA), Gwyn A. Evans, FRCS, and Nicolas Lubega, FCS (ECSA)

J Pediatr Orthop Volume 29, Number 7, October/November 2009 Chronic Hematogenous Osteomyelitis in Children

Classification• Type A—Brodie’s abscess,

• Type B—Sequestrum involucrum,

B1-Localised cortical sequestrum B2-Sequestrum with normal /structural involucrum* B3-Sequestrum with sclerotic involucrum B4-Sequestrum without structural involucrum

• Type C—sclerotic.

If proximal physis is damaged the suffix P is added If distal physis is affected the suffix D is added * Adequate involucrum to support wt of limb against gravity

Example of type A: Brodie’s abscess within a distal tibia

Example of type C: sclerotic tibia.

Beit CURE Classification of Childhood Haematogenous Chronic Osteomyelitis

Example of type B1:localised cortical sequestrum of a tibia.

Example of type B2: sequestrum with normal structural involucrum of a proximal humerus.

Beit CURE Classification of Childhood Haematogenous Chronic Osteomyelitis

Example of type B3: sequestrum with sclerotic involucrum of a radius.

Example of type B4: sequestrum with structurally inadequate involucrum of a tibia.

Beit CURE Classification of Childhood Haematogenous Chronic Osteomyelitis

TREATMENTMEDICAL• Specific antimicrobial coverage• In compromised host—correct or reduce the host

defect

SURGICAL• Adequate drainage• Debridement• Obliteration of dead space• Adequate soft tissue cover for wound protection• Restoration of an effective blood supply

ANTIBIOTIC TREATMENT• Chronic infection develops in 19% of pt with acute

osteomyelities receiving antibiotics for 3 wks or less---BUT only 2% in patients receiving longer than 3 wks

• Cierny-Mader stage 1,3,4 require 4 - 6 wks of antibiotics (revascularisation of bone after debridement takes about 4 wks)

• Stage 2—short course antibiotics for 2 wks following debridement of cortex/soft tissue

• Stage 3 /4 –antibiotics for 4 to 6 wks from last major decompression/debridement

ANTIBIOTICSIV antibiotics• Nafcillin/oxacillin/nafcillin with rifampcin *• Vancomycin/ampcillin/cefazolin/ceftriaxone• Clindamycin/sulbactum/piperacillin/tazobactamORAL antibiotics• Clindamycin/rifampcin/cotrimexazole• Fluroquinolones in gram –ve organisms• Linezolid-oral & IV antibiotics—MRSA

• Not necessary to follow serum bactericidal levels-failure are due to lack of adequate surgical debridement rather than inadequate antibiotic efficiency

• In children the benefits of Quinolones if required are much more than toxicity to joint which is rare except in cystic fibrosis

Ball p et all drug safe 1999;21:407-21

Out Patient Parentral Antibiotic Therapy OPAT

• 51% courses associated with ADE(adverse drug event)• 32.5% of antibiotics were discontinued because of ADE• Vancomycin has highest ADE rate (85.7%)• Ceftrixone has highest discontinuation rate of 66.7%• Cefazolin had the lowest rate of ADE & ADE related

discontinuation rate at 0% for both• Leukopenia/hepatitis/rash (Paediatric Infectious disease journal ,july 2009)

OPERATIVE TREATMENT

Bone debridement• Complete removal of all infective / devascularized tissue –only solution to eradicate infection—a/b cannot reach• “Paprika sign” –punctate bleeding• Extent of operative debridement- (simpson et all)• >5 mm wide resection-no recurrence• <5 mm marginal resection had recurrence of 28%• Extent of debridement is much more important in B hosts• Cortical window- at weakest area of the involucrum -connect a series of drill holes -should be oval to mimimise risk of # • IF INITIAL DEBRIDMENT IS IN DOUBT RETURN TO OT FOR ADDITIONAL DEBRIDEMENT

In either case it is critical to preserve the involucrum

preferable to wait at least 3-6 mo before performing a sequestrectomy

Early sequestrectomy- Eradicate infection- Better environment for

periosteum to respond

Delayed sequestrectomy Wait till sufficient involucrum

has formed before doing a sequestrectomy to mimimize the risk of cx, fracture, deformity & segmental loss

When to do sequestrectomy?

SEQUESTRUM

Post sequestrectomy• NO STABLISATION IS

NECESSARY WHEN 70% OF THE ORIGINAL CORTEX REMAINS INTACT

• If >70% cortical volume has been retained—protect by cast

• Greater bone loss-Ext fix• Focal bone loss-open

cancellous BG/conventional BG

• Seg. bone loss—BG/Bone transport/other devices

Radiologically if cortical continuity of the involucrum is 50% of the over all cortical diameter on 2 orthogonal views then the involucrum is structurally adequate

The sequestrum here is a large segment of the tibial diaphysis, and a suitable involucrum had formed posteriorly and laterally . At the time of exposure, that segment was avascular in contrast to the surrounding bone and soft tissue. The segment was easily removed.

The failure to form an adequate involucrum will result in segmental bone loss.

Culture Blood ± bone

Initial antibiotic selection

Change or confirm d/o culture results

Poor response

Operative treatment unroofing ,abscess drainage,

IM reaming

4 wks antibiotics

Failure

Retreat as above

Arrest

Good response

Continue 2 wks parenteral & 4 wks Oral

antibiotics

Treatment algorithm of Cierny-Mader Stage-1, or hematogenous, long-bone osteomyelitis.

Hardware removal

Bone stable

Hardware removal IM reaming

AntibioticsContinue 2 wks parenteral & 4

wks Oral

Failure

Retreat as above

Arrest

Bone unstable

Suppressive antibiotic treatment until

stabilisation

Treatment algorithm of Cierny-Mader Stage-1 long-bone osteomyelitis associated with infection at the site of hardware

Superficial debridement

Biopsy & culture

Initial antibiotic selection

Change or confirm based on culture results

Continue antibiotics for 2 wks

± Local or microvascular coverage

Treatment algorithm of Cierny-Mader Stage-2 long-bone osteomyelitis

Biopsy & Culture

Initial antibiotic selection

Change or confirm d/o culture results

6wks antibiotics after major operative

debridement

Failure

Retreat as above

Arrest

Debridement

Hardware removal

Dead space management, beads, bone grafts, &

muscle flaps

Stabilisation external fixation

Ilizarov technique

Soft tissue coverage

Treatment algorithm of Cierny-Mader Stages-3 and 4 long-bone osteomyelitis.

Osteomyelitis in long bones, L . Lazzarini,J.T.Mader,JBJS.Am.2004;86:2305-2318

Chronic OM with segmental bone loss

• Either partial or entire• Forearm/lower limb-by pass procedures may be

used to restore stability—HUNTINGTON PROCEDURE & VARIANTS

• Bone transport by illizarov is an alternative to conventional grafting

Chronic OM with segmental bone loss

Fibular by pass procedure-one- or two-stage transfer

(Huntington procedure and variants)

No involucrum one yr after onset of the disease.

2 mo post sequestrectomy/ strut graft

7 yr/ F

8 mo- graft resorbed corticocancellous graft done

4 mo post grafting –fusion

Chronic OM with focal bone loss• Small defect are managed by protection—cast

or ext fixator until loss has been reconstructed

• In young children regeneration of entire tibial shaft has been documented

• Open cancellous bone graft-3- stage technique of papineau

• Conventional bone grafting

ANTIBIOTIC IMPREGNATED PMMA BEADS

• Delivery level of antibiotic locally in conc. that exceeds the MIC

• Local concentration of antibiotic are 200 times higher than systemic concentration

• Leaching/elution of antibiotic• Heat labile/heat stable antibiotic• Porous high viscosity cement surface area & elution of antibiotic

• Aminoglycoside /cephalosporin/ clindamycin• Vancomycin- MRSA

• Remove beads at 6 wks- Cx is foreign body formation, on which glycocalyx forming bacteria colonise & inhibit local phagocytic immune cells

• BIOGRADABLE ANTIBIOTIC DELIVERY SYSTEM Tobramycin-impregnated calcium sulfate pellets- only one study by Mckee

• VAC- aids in healing of soft tissue wounds negative pressure- wound shrinkage, resorbs fluid, granulation tissues

RECONSTRUCTION OF BONE DEFECT & MANAGEMENT OF DEAD SPACE

• Closed irrigation and suction system—ingress/ egress/ high volume irrigation/contamination risk/3-21 days

• Papineau tech-open cancellous bone grafting• Free vascularised bone graft- fibula/ilium• Well vascularised local tissue flap/free flap-

used to fill dead space• Bone transport or Illizarov technique

SOFT TISSUE COVERAGE

• Healing by secondary intention is to be avoided to avoid avascular scar.

Types-• Split thickness skin graft• Local muscle flap• Free vascular muscle flaps—e.g latissimus dorsi, rectus abdominus,

gracilis

Free muscle flapsFree muscle or musculocutaneous flap- Advantages• Dead space obliteration/coverage• Better & easier for filling all irregular cavities• Can be divided & split into exact size & form to

permit transfer to bone and soft tissue defect• Can be easily anchored without internal fixation• FREE GRACILIS MS FLAP- harvested from opp. thigh

based on its vascular pedicle- circumflex femoris medialis

• 60% to 100% of flap cover wounds healed compared to 40% with open cancellous bone grafting

Resistant chronic OM (avg. procedure per pt 2.3)

Yeargan et al, J Pediatr Orthop , Volume 24, Number 1, January/February 2004

Thank you

drvasurao85@yahoo.com