G21_Osteomyelitis

8/6/2019 G21_Osteomyelitis

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Osteomyelitis:

Pathophysiology &

Treatment Decisions

Clifford B. Jones, MDClinical Assistant Professor, Michigan State University

Orthopaedic Associates of Grand Rapids, Grand Rapids, MI

Created March 2004


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Introduction

350,000 long bone fxs/yr

Infection risk varies: Type I open 10/1,000 infections

Type III open up to 25%


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Cost Analysis

Infection

Increase cost 16-21% / pt Increase hosp stay 36-50% / pt

Total Cost $ 271 million/yr


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Definition Group of conditions

presence of bacteria & an inflammatory

response causing progressive destruction of

bone. Fears, RL, et al, 1998

suppurative process in bone caused by apyogenic organism

Pelligrini, VD, et al, 1996


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Why Destruction of Bone Matrix?

Proteolytic enzymes

Hyperemia

Osteoclasts


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Inflammation Time Table


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Principles of Treatment Clinical Staging

Characterize disease

Characterize host

Match treatment options to patient

Staged reconstruction Appropriate antibiotic coverage

Delayed return for osseous reconstruction


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Classification Waldvogel, 1971

Classification based on pathogenesis

May, 1989

5 parts, post-traumatic tibial osteomyelitis

Cierny & Mader, 1985

4 factors affecting outcome Host, site, extent of necrosis, degree of

impairment


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May Classification


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PathogenesisWaldvogel, 1971

1. Hematogenous

2. Contiguous focus of infection

3. Direct inoculation


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Cierney & Mader Class.


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Anatomic

Classification

(Cierny-Mader)

1985


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Classification Break-Down

I. Medullary Endosteal nidus, minimal soft tissue involvement, ? Sinus tract

II. Superficial Localized to surface of bone, usually 2 to soft tissue defect

III. Localized Localized sequestra, usually associated sinus tract

Bone structurally stable s/p excision

IV. Diffuse Permeative process, combination of I/II/III,

Commonly unstable s/p excision


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Physiologic Classification

(Cierny-Mader, 1985)A-Host: Good immune system & delivery

B-Host: Compromised host

BL: locally compromised

BS:systemically compromised

BC: combined

C-Host: Requires suppressive or no TxMinimal disability

Treatment required to eliminate disease worse than disease, not

a surgical candidate


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Host Alteration

(optimization) Patient education

Nutrition

No tobacco (including snuff)

Preoperative antibiotics

Perioperative antibiotics

Address compromised areas Local

Systemic ( fine tune chronic disease)


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Clinical Staging(Cierny-Mader, 1985)

Anatomic Type

+ Clinical Stage

Physiologic Class

Example: IV BS

tibialosteomyelitis = diffuse tibiallesion ina systemicallycompromised host


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Types of Pathophysiology Acute/Hematogenous

Chronic/Nonhematogenous


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Acute/Hematogenous

Anatomy (Hobo)

Sharp twist in metaphyseal capillaries

Stasis (Trueta)

Decreased flow in capillaries & veins

Combination (Morrissy)

Trauma & Bacteria


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Acute/Hematogenous

Progression of Disease

Cell death 2 to bacterial exotoxins

bacterial culture medium

worsens condition

o vacularity, leukocytosis, edema

Pressure w/in rigid osseous container Pain, swelling, erythema

Potential for septic arthritis (knee, hip, shoulder)


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Possible Clinical Findings

*Signs and symptoms variable

None

Pain

Tenderness

Fever

HA Nausea/Vomiting

Erythema

Swelling

Sinus Tract

Drainage

Limp Fluctuence


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Clinical Findings Must have high index of suspicion

Inappropriate use of antimicrobials

obscure signs and symptoms

Must obtain diagnosis quickly

If appropriate treatment started < 72:

Decrease incidence of chronic osteomyelitis

Decrease destruction of bone


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Radiographs Early negative

changes usually delayed (10-21 days)


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Radiographs Soft Tissue

Swelling, obscured soft tissue planes, haziness

Osseous

Hyperemia, demineralization

Lysis (when > 40% resorbed)

Periosteal reaction

Sclerosis (late)


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Radionucleotide Imaging

99M Tc

67Ga

111InWBC


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99M Tc

Action

binds to hydroxyapetite crystals

Osteoblastic activity

Demineralized bone

Immature collagen


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99M Tc

3 Phase Bone Scan

1. Radionucleotide angiogram

2. Immediate post injection blood pool

3. Three hour: q soft tissue, urinary excretion

Diagnosis

Cellulitis: o Phases 1 &2, no change 3

Osteomyelitis: o Phases 1 & 2, focal o 3

Results: 94% sensitivity, 95% specificity

Rosenthal1992, Schauwecker 1992


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Cellulitis


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Osteomyelitis


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99M Tc: False Positive

DM foot disorders

Septic arthritis Inflammatory bone disease

Adjacent to pressure sores


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99M Tc

4 Phase Bone Scan

New development

Action: Mature bone: uptake stops at 4 hr

Immature woven bone: contd uptake at 24 hr

Problem: needs f/u imaging at 24 hr (compliance) Gupta 1988, Israel1987, Schauwecker 1992


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67Ga

Exudation of in vivo labeled serum protein

Transferrin, haptoglobin, albumin

Results

81% sensitivity, 69% specificity Schauwecker, 1992

Combination with Tco sensitivity, but q specificity


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111InWBC

Used in combination (Seabold, 1989)

In/Tc: 88% accurate

Ga/Tc: 39% accurate

Preparation problem

o rad dose to spleen, 18-24hr delay

Spine (Whalen, Spine 1991) 83% false negative

Recommended use of MRI


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MRI No radiation

Good soft tissue imaging

Imaging:

TI dark

T2 Bright/Mixed


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T1 bright T2 dark


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T1 bright T2 dark


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MRI Acute:

q marrow fat

o granulation tissue H2O

Chronic: thickened cortex

Low signal on all scans Cellulitis: no marrow changes


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MRI ResultsSchauwecker, 1992

Sensitivity 92-100%

Specificity 89-100%

Excellent for Spine (Modic, RCNA, 1986)

Sens 96%, Spec 92%, Accuracy 94%

Evaluates soft tissue extension

Sinus tract formation

Bright Tx from skin to bone


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CT Imaging Image cortical and cancellous bone

Evaluate osseous adequacy of debridement


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Aspiration Biopsy Acute

Good, only 10-15% false negative

Chronic

Sinus tract culture: 76% sens, 80% spec

70% with Saureus & Enterococcus

30%Pseudomonas

Does not determine correct Abx


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Acute/Hematogenous


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Changing Bacterial Pathogens


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Antibiotics Changing sensitivities

Newer oral agents

Consult Infectious Disease Colleague for

recommendations regarding specifics of

dosage, route ofadministration, and

duration


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Local Antibiotic Delivery PMMA beads

staged reconstruction

retained

Cancellous bone graft

Biodegradable bead

Deliver antibiotic without need for removal


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Long Bone Segmental Defect Free vascularized bone

Fibula-pro-tibia

Massive cancellous autograft

Acute shortening/lengthening

Single-level bone transport

Double-level bone transport


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Ilizarov External Fixator Wound stabilization

Limb stabilization

Acute shortening/lengthening

Correction of deformity

Static fixation

Bone transportation


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Examples


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Example 1

54 yo Male

Post-operativePseudomonas osteomyelitis

Refractory to HW removal & Ancef Healthy, non-smoking

Cierny III A Host

Photos from M Swiontkowski


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Example 1

Dead Space

Calcaneal defect


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Example 1

Debridement of all non-viable bone with

laser doppler

Defect filled with antibiotic PMMA

6 wks antibiotics


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Example 1, at 6 wks

Removal Abx beads

Bone grafting

Lateral arm flap

Infection eradication


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Example 2

47 yo Male, smoker

Presentation 2 months s/p ORIF closed proximal

tibia fx Draining wound

Exposed HW

Cierny III BC Host



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Example 2

Debridement

Hardware remains

Antibiotic beads

Exposed plate


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Example 2

Gastrocnemeus flap, STSG


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Example 2

At 6 weeks

Remove Abx beads

Bone grafting

Healed wound and fracture


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Example 3

At 5 yo, tibial osteomyelitis

Partially treated

At 62 yo, presentation to MD

Chronic draining tibial osteomyelitis

Cierny III BC Host



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Example 3

Sinus tracts

Chronic skin changes


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Example 3

I&D to normal bleeding

bone with laser doppler

Bx negative for cancer


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Example 3

Antibiotic beads

Latissimus Flap

STSG


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Example 3

Removal Abx beads at 6 wks

No bone graft low demand

patient

Disease free at 8 years


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Conclusion

Prevention best

High suspicion

Early intervention

Obtain deep

cultures

Aggressive

debridement

Appropriate Abx

Early coverage

Stabilize

appropriate sites

Strive for function

and cure

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