orthopaedics and trauma

1. Osteomyelitis:
Pathophysiology &
Treatment Decisions
Clifford B. Jones, MD
Clinical Assistant Professor, Michigan State University
Orthopaedic Associates of Grand Rapids, Grand Rapids, MI

2. Introduction
• 350,000 long bone fxs/yr
• Infection risk varies:
– Type I open – 10/1,000 infections
– Type III open – up to 25%

3. Cost Analysis
• Infection
–Increase cost 16-21% / pt
–Increase hosp stay 36-50% / pt
• Total Cost ⇒ $ 271 million/yr

4. 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 a
pyogenic organism”
– Pelligrini, VD, et al, 1996

5. Why Destruction of Bone Matrix?
• Proteolytic enzymes
• Hyperemia
• Osteoclasts

7. Inflammation Time Table

8. Principles of Treatment
• Clinical Staging
– Characterize disease
– Characterize host
• Match treatment options to patient
• Staged reconstruction
• Appropriate antibiotic coverage
• Delayed return for osseous reconstruction

9. 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

10. May Classification

11. Pathogenesis
Waldvogel, 1971
1. Hematogenous
2. Contiguous focus of infection
3. Direct inoculation

12. Cierney & Mader Class.

13. Anatomic
Classification
(Cierny-Mader)
1985

14. Classification Break-Down
I. Medullary
• Endosteal nidus, minimal soft tissue involvement, ? Sinus tract
I. Superficial
• Localized to surface of bone, usually 2° to soft tissue defect
I. Localized
• Localized sequestra, usually associated sinus tract
• Bone structurally stable s/p excision
I. Diffuse
• Permeative process, combination of I/II/III,
• Commonly unstable s/p excision

15. Physiologic Classification
(Cierny-Mader, 1985)
A-Host: Good immune system & delivery
B-Host: Compromised host
B
L
: locally compromised
B
S
: systemically compromised
B
C
: combined
C-Host: Requires suppressive or no Tx
Minimal disability
Treatment required to eliminate disease worse than disease, not
a surgical candidate

16. Host Alteration
(optimization)
• Patient education
• Nutrition
• No tobacco (including “snuff”)
• Preoperative antibiotics
• Perioperative antibiotics
• Address compromised areas
– Local
– Systemic ( fine tune chronic disease)

17. Clinical Staging
(Cierny-Mader, 1985)
Anatomic Type
+ Clinical Stage
Physiologic Class
Example: IV B
S
tibial osteomyelitis = diffuse tibial lesion in
a systemically compromised host

18. Types of Pathophysiology
• Acute/Hematogenous
• Chronic/Nonhematogenous

19. Acute/Hematogenous
• Anatomy (Hobo)
– Sharp twist in metaphyseal capillaries
• Stasis (Trueta)
– Decreased flow in capillaries & veins
• Combination (Morrissy)
– Trauma & Bacteria

20. Acute/Hematogenous
Progression of Disease
• Cell death 2° to bacterial exotoxins
 bacterial culture medium
 worsens condition
∀ ↑ vacularity, leukocytosis, edema
 Pressure w/in rigid osseous container
 Pain, swelling, erythema
Potential for septic arthritis (knee, hip, shoulder)

21. Possible Clinical Findings
*Signs and symptoms variable
• None
• Pain
• Tenderness
• Fever
• HA
• Nausea/Vomiting
• Erythema
• Swelling
• Sinus Tract
• Drainage
• Limp
• Fluctuence

22. 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

23. Laboratory Data
• Acute (Morrey BF, OCNA, 1975)
↑ WBC (25% of time)
– Abnormal differential, Left Shift (65%)
– Blood Culture
• 50% positive
• Chronic
– Mild anemia,
– Elevated WESR, C-reactive protein
– Possible leukocytosis with L shift
– Blood Culture – usually negative

24. Radiographs
• Early – negative
– changes usually delayed (10-21 days)

25. Radiographs
• Soft Tissue
– Swelling, obscured soft tissue planes, haziness
• Osseous
– Hyperemia, demineralization
– Lysis (when > 40% resorbed)
– Periosteal reaction
– Sclerosis (late)

26. Radionucleotide Imaging
• 99M
Tc
• 67
Ga
• 111
In WBC

27. 99M
Tc
• Action
– binds to hydroxyapetite crystals
• Osteoblastic activity
– Demineralized bone
– Immature collagen

28. 99M
Tc
• 3 Phase Bone Scan
1. Radionucleotide angiogram
2. Immediate post injection blood pool
3. Three hour: ↓ soft tissue, urinary excretion
• Diagnosis
– Cellulitis: ↑ Phases 1 &2, no change 3
– Osteomyelitis: ↑ Phases 1 & 2, focal ↑ 3
• Results: 94% sensitivity, 95% specificity
– Rosenthal 1992, Schauwecker 1992

29. Cellulitis

30. Osteomyelitis

31. 99M
Tc: False Positive
• DM foot disorders
• Septic arthritis
• Inflammatory bone disease
• Adjacent to pressure sores

32. 99M
Tc
• 4 Phase Bone Scan
• New development
• Action:
– Mature bone: uptake stops at 4 hr
– Immature woven bone: cont’d uptake at 24 hr
• Problem: needs f/u imaging at 24 hr (compliance)
• Gupta 1988, Israel 1987, Schauwecker 1992

33. 67
Ga
• Exudation of in vivo labeled serum protein
– Transferrin, haptoglobin, albumin
• Results
– 81% sensitivity, 69% specificity
– Schauwecker, 1992
• Combination with Tc
↑ sensitivity, but ↓ specificity

34. 111
In WBC
• Used in combination (Seabold, 1989)
– In/Tc: 88% accurate
– Ga/Tc: 39% accurate
• Preparation problem
↑ rad dose to spleen, 18-24hr delay
• Spine (Whalen, Spine 1991)
– 83% false negative
– Recommended use of MRI

35. MRI
• No radiation
• Good soft tissue imaging
• Imaging:
– TI dark
– T2 Bright/Mixed

36. T1 bright T2 dark

37. T1 bright T2 dark

38. MRI
• Acute:
↓ marrow fat
↑ granulation tissue H2O
• Chronic: thickened cortex
– Low signal on all scans
• Cellulitis: no marrow changes

39. MRI Results
Schauwecker, 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

40. CT Imaging
• Image cortical and cancellous bone
• Evaluate osseous adequacy of debridement

41. Aspiration Biopsy
• Acute
– Good, only 10-15% false negative
• Chronic
– Sinus tract culture: 76% sens, 80% spec
• 70% with S aureus & Enterococcus
• 30% Pseudomonas
• Does not determine correct Abx

42. Acute/Hematogenous

43. Changing Bacterial Pathogens

44. Antibiotics
• Changing sensitivities
• Newer oral agents
Consult Infectious Disease Colleague for
recommendations regarding specifics of
dosage, route of administration, and
duration

45. Local Antibiotic Delivery
• PMMA beads
– staged reconstruction
– retained
• Cancellous bone graft
• Biodegradable bead
– Deliver antibiotic without need for removal

46. Dead Space Management
• Free tissue transfer
• Rotational tissue transfer
• Cancellous bone grafting
• PMMA beads
• Acute shortening
• Bone transport
• Trabecular metal

47. Long Bone Segmental Defect
• Free vascularized bone
• Fibula-pro-tibia
• Massive cancellous autograft
• Acute shortening/lengthening
• Single-level bone transport
• Double-level bone transport

48. Ilizarov External Fixator
• Wound stabilization
• Limb stabilization
• Acute shortening/lengthening
• Correction of deformity
• Static fixation
• Bone transportation

49. Examples

50. Example 1
• 54 yo Male
• Post-operative Pseudomonas osteomyelitis
• Refractory to HW removal & Ancef
• Healthy, non-smoking
• Cierny III A Host
Photos from M Swiontkowski

51. Example 1
•Dead Space
•Calcaneal defect

52. Example 1
• Debridement of all non-viable bone with
laser doppler
• Defect filled with antibiotic PMMA
• 6 wks antibiotics

53. Example 1, at 6 wks
• Removal Abx beads
• Bone grafting
• Lateral arm flap
• Infection eradication

54. Example 2
• 47 yo Male, smoker
• Presentation 2 months s/p ORIF closed proximal
tibia fx
• Draining wound
• Exposed HW
• Cierny III BC
Host
• Photos from M Swiontkowski

55. Example 2
• Debridement
• Hardware remains
• Antibiotic beads
Exposed plate

56. Example 2
• Gastrocnemeus flap, STSG

57. Example 2
• At 6 weeks
• Remove Abx beads
• Bone grafting
• Healed wound and fracture

58. Example 3
• At 5 yo, tibial osteomyelitis
• Partially treated
• At 62 yo, presentation to MD
• Chronic draining tibial osteomyelitis
• Cierny III BC
Host
• Photos from M Swiontkowski

59. Example 3
•Sinus tracts
•Chronic skin changes

60. Example 3
•I&D to normal bleeding
bone with laser doppler
•Bx – negative for cancer

61. Example 3
• Antibiotic beads
• Latissimus Flap
• STSG

62. Example 3
• Removal Abx beads at 6 wks
• No bone graft – low demand
patient
• Disease free at 8 years

63. 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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