1
Q
Osteomyelitis
- Define
A
- Inflammation of bone that is almost always due to infection
- MC bacterial but can be viral or fungal as well
2
Q
Three ways to classify osteomyelitis
A
- timing
- mechanism of injury
- type of host response
3
Q
Osteomyelitis classification
- timing
A
- Acute <2 weeks
- Subacute 2-6 weeks
- Chronic > 6 weeks
4
Q
Osteomyelitis classification
- Mech. of injury
A
- Exogenous: originates from outside the body
- Hematogenous: originates from body itself
5
Q
Osteomyelitis classification
- host response
A
- Pyogenic: produces pus from infecting org
- Non-pyogenic: no abscess or pus production
6
Q
Keys to clinical success
A
- Early dx
- Appropriate surgical and antimicrobial treatment (may require multidisciplinary approach: ortho, ID, plastics)
7
Q
Three types of osteomyelitis studied
A
- acute hematogenous
- subacute hematogenous
- chronic
8
Q
What is MC type of osteomyelitis
A
Acute Hematogenous
9
Q
Acute Hematogenous Osteomyelitis
- ages affected
A
- MC <2 and 8-12
- MC in males
- can occur in adults
10
Q
Acute Hematogenous Osteomyelitis
- areas of bone effected
A
- children: long bone metaphysis d/t bacteremia MC
- adults: vertebrae MC, also long bones, pelvis, clavicle
11
Q
Acute Hematogenous Osteomyelitis
- was is bacterial seeding associated with?
A
- localized trauma
- chronic illness
- malnutrition
- inadequate immune system
12
Q
Acute Hematogenous Osteomyelitis
- overview of patho in children
A
- Metaphysis is rapidly growing and has a lot of vasculature
- Bacterial seeding → inflammatory rxn, causing localized ischemic necrosis of bone and subsequent bone abscess formation
- Abscess enlarges, causing intramedullary pressure, cortical ischemia and destruction.
- The purulent infectious material can escape the cortex and enter the subperiosteal space → subperiosteal abscess
13
Q
Acute Hematogenous Osteomyelitis
- what happens if untreated?
A
extensive sequestra formation and chronic osteomyelitis
14
Q
Acute Hematogenous Osteomyelitis
- two major complications
A
- Involcrum: thick sheath of periosteal new bone surrounding a sequestrum
- Sequestrum:
- Devascularization of a portion of bone with necrosis and resorption of surrounding bone leaving a “floating” piece
- Acts as a reservoir for infection
- Avascular = not penetrated by abx, usually requires excision
15
Q
Acute Hematogenous Osteomyelitis
- pathophys for children <2 yo
A
- Blood vessels cross the physis, allowing epiphysis involvement
- Can result in limb shortening or angular deformities
- Contiguous joint involvement can occur, more likely if involves intra-articular physis: MC is hip, also proximal humerus, radial neck, distal fibula. Can results in septic arthritis
- Metaphysis has relatively fewer phagocytic cells than physis or diaphysis = more infection potential
16
Q
Acute Hematogenous Osteomyelitis
- pathophys children >2 yo
A
- Physis acts like a barrier to spread from metaphyseal abscess
o Once physis is closed, acute hematogenous osteomyelitis is much less common
o Once physis is closed, infection can extend directly from metaphysis into epiphysis and involve the joint (why septic arthritis from acute hematogenous osteomyelitis is seen only in infants and adults) - The metaphyseal cortex is thicker so diaphysis is at more risk
17
Q
Acute Hematogenous Osteomyelitis
- microbiology
A
- Older children and adults: Staphylococcus aureus
- Infants: S. aureus. Also Group B Streptococcusand gram negative coliforms
- Premature neonates: S. aureus and gram neg orgs
- Incidence of Hemophilus influenza decrease d/t immunizations, MC in children 6 months – 4 years
- Adult vertebral infection: gram negative bacteria
- IV drug users: Pseudomonas
- Sickle cell: Salmonella, tends to be diaphyseal
- Chronically ill, long term IV therapy: fungal infections
18
Q
Acute Hematogenous Osteomyelitis
- Hx and PE
A
- Fever, malaise
- Pain, localized tenderness
- Swelling
- Compartment syndrome in children
19
Q
Acute Hematogenous Osteomyelitis
- Labs for dx
A
- CBC: often have NL WBC
- CRP: usu elevated. Repeat 2-3 days after abx
- ESR no longer used, replaced by CRP
- Abscess or bone aspiration for C&S
20
Q
Acute Hematogenous Osteomyelitis
- Imaging for dx
A
- Plain films: usu not visible for 10-12 days
- Technetium 99m bone scan: can confirm dx 24-48 hours after onset in 90-95% of cases
- MRI: early inflammatory changes in bone marrow or soft tissue involvement
21
Q
Acute Hematogenous Osteomyelitis
- Tx overview
A
- No abscess, abx may be sufficient: empirical coverage, if no response in 24-48 hours, then occult abscesses must be sought, surgical drainage considered
- Often abx and surgery required
22
Q
Acute Hematogenous Osteomyelitis
- Nade’s Principles of treatment
A
- Abx will be appropriate before pus formation
- Abx will not sterilize avascular tissue or abscesses, will require surgical debridement (refer to ortho)
- If removal is effective, ax will prevent reformation so primary wound closure should be safe
- Surgery should not further damage already ischemic bone and soft tissue
Abx should be considered after sx
23
Q
Acute Hematogenous Osteomyelitis
Surgery
- 2 indications
- 2 objectives
A
Indications
• Presence of abscess that requires drainage
• Failure of pt to improve despite IV abx
Two objectives
• Drain abscess cavity
• Remove nonviable or necrotic tissue
24
Q
Subacute Hematogenous Osteomyelitis
- overview
A
More insidious onset; lacks severity of sx compared to acute
25
Subacute Hematogenous Osteomyelitis
| - why is dx often delayed?
Often 2+ weeks, indolent course bc:
- Increased host resistance
- Decreased bacterial virulence
- Admin of abx before onset of sx
26
Subacute Hematogenous Osteomyelitis
| - Hx and PE
- Minimal systemic s/sx
- Mild temp elevation
- Mild-mod pain
27
Subacute Hematogenous Osteomyelitis
| - Dx
Labs
- CBC: WBC general NL
- ESR: elevated in only 50% of pts
- Blood cultures: gen negative
Plain film: generally positive
28
Subacute Hematogenous Osteomyelitis
| - organisms
Staph aureus and Staph epidermidis
29
Subacute Hematogenous Osteomyelitis
| - Brodie abscess describe
- Localized form of subacute osteomyelitis
- S. aureus positive culture in 50%
- MC in long bones of LE
- MC complaint: intermittent pain of long duration and tenderness over affected area
30
Subacute Hematogenous Osteomyelitis
| - Brodie abscess on plain film
lytic lesion with a rim of sclerotic bone
31
Subacute Hematogenous Osteomyelitis
| - Brodie abscess dx
- Aggressive lesions require open bx with curettage
| - Simple abscess in epiphysis or metaphysis: bx not recommended. Just IV abx X 48 hours + 6 weeks oral abx
32
Subacute Hematogenous Osteomyelitis
| - Brodie abscess tx
- close wound loosely over drain (if open bx with curettage)
| - abx
33
Subacute Hematogenous Osteomyelitis
| - Brodie abscess classification
Gledhill classification
34
Chronic osteomyelitis
| - hallmark sx
- Infected dead bone with compromised soft tissue envelope
- Infected focci in bone are surrounded by sclerotic, relatively avascular bone with thickened periosteum and scarred muscle and subcutaneous tissue
35
Chronic osteomyelitis
| - Types
- Medullary: in the medulla
- Superficial: cortical surface infected d/t coverage defect
- Localized: cortical sequestrum, can be excised w/o compromising stability
- Diffuse: features of all other types, mechanical instability before or after debridement
36
Chronic osteomyelitis
| - Hx and PE
- Skin/soft tissue integrity
- Tenderness
- Bone stability
- Neurovascular status of limb
- Presence of sinus track
37
Chronic osteomyelitis
| - lab dx
- ESR and CRP
- WBC elevated 35%
- Bx for histological and microbiological eval: staph. aureus, anaerobes, gram-neg bacilli
38
Chronic osteomyelitis
| - Imaging overview
- Plain film
- Sinography (nuclear med)
- Isotropic bone scanning (more useful in acute vs. chronic)
- Gallium scan
- CT
- MRI
39
Chronic osteomyelitis
| - Plain film
** takes 10-12 days to show up
• Cortical destruction
• Periosteal reaction
• Sequestra
40
Chronic osteomyelitis
| - Gallium scan
* Increased uptake where leukocytes and bacteria accumulate
| * NL scan excludes osteomyelitis
41
Chronic osteomyelitis
| - CT scan
* ID sequestra
| * Define cortical bone and surrounding soft tissue
42
Chronic osteomyelitis
| - MRI
• Shows bone margin and soft tissue edema
• Eval reoccurrence after 1 year
• Rim sign: well defined rim of high signal intensity surrounding focus of active dz
Tx
43
Chronic osteomyelitis
| - Tx
- Sx is usually needed: remove sequestra, resection of damaged tissue, debridement
- Abx, duration is controversial
- Amputation if arterial insufficiency, major nerve paralysis, malignant change, non-functional limb stiffness
44
Chronic osteomyelitis
| - Sclerosing Osteomyelitis of Garre'
- Bone thickened and distended but no abscess or sequestra
| - Unknown cause, possibly low-grade, anaerobic bacteria
Infectious Disease 2
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