Osteomyelitis Flashcards
Osteomyelitis - definition
Infection in bone
Acute Osteomyelitis - definition
Associated with inflammatory bone changes by pathogenic bacteria and s/s typically present within 2 weeks after infection
Chronic Osteomyelitis - definition
Necrotic bone with s/s that may not occur until 6 weeks after the onset of infection
Generally secondary to open fx, bacteremia or contiguous bone infection
How does Osteomyelitis occur
Hematogenous dissemination of bacteria
Invasion from a contiguous focus of infection
Skin breakdown in the setting of vascular insufficiency
Where does Osteomyelitis occur
Spine Cancellous portions of long bones Pelvis Calvicle Previously injured bone or bone in close proximity to area of infection
Who does Osteomyelitis occur in?
Peds
- etiology is uslaly hematogenous
- most common anatomic area - vascular metaphysis of long bones
Adults
- innoculation of organism through open fx or sx fixation of fx
- hematogenous is much less common than in kids - if it occurs, will be in the vertebra, long bones, pelvis or clavicle
Organisms of Osteomyelitis in peds
S. aureus - most common Group A beta-hemolytic strep Others - Strep penumonia - H. flu (less prevalent now) - Kingella Kingae - Group B strep infection (newborns)
Organisms of Osteomyelitis in adults
S. aureus - most common Pseudomonas aeruginosa MRSA Staph epidermidis Serratia marcescens E. coli Atypical organisms in immunocompromised pts Others - M. TB - Candida species - Coccidoidomycosis immitis
RF for Hematogenous Osteomyelitis
Children Sickle cell dz IV drug use DM Chronic Renal Dz Elderly
Why are children at risk for hematogenous Osteomyelitis
Metaphyseal regions of long bones are highly vascular and susceptible to minor trauma
> 50% of acute hematogenous osteomyelitis are in pts <5yo
Organism most common for hematogenous osteomyelitis in sickle cell dz pts
Salmonellae
IV drug use and hematogenous osteomyelitis
Typically osteomyelitis of the spine
S. aureu (most common) then Gram negative, esp. P. aerginose and Serratia species
The elderly and hematogenous osteomyelitis
Thoracic and lumbar vertebra RF - DM - IV catheters - Urinary catheters
Causes of soft tissue infections that can spread to the bone
Prosthetic joint replacement Pressure ulcer Neuro sx Trauma Septic arthritis Cellulits
Vascular insufficiency and osteomyelitis
Pts with DM or vascular insufficiency at greatest risk
Foot and ankle are most likely sites
Infection originates from ulcer or skin breakdown
Big source of chronic osteomyelitis
Vascular insufficiency & osteomyelitis - symptoms
Chronic pain Persistent sinus tract or wound drainage Poor wound healing Malaise Sometimes fever
Vascular insufficiency and osteomyelitis - important clues
Pass sterile probe through ulcer to bone
Ulcer >2cm*cm
Polymicrobial infections of vascular insufficiency and osteomyelitis
S. aureus
Staph epidermidis
Clinical Presentation - neonates
Vague s/s Malaise Lethargy Pseudo-paralysis Excessive crying Irritability Fever Local swelling Pain with palpation
Clinical presentation - children
Fever
Pain
Swelling of infected site
Clinical presentation - Adults (hematogenous)
Back pain along with Hx of DM Ca Chronic renal dz IV drug use
Clinical presentation - Adults (vascular insufficiency with DM)
Chronic pain Persistent sinus tract or wound drainage Poor wound healing Malaise Sometimes fever
Clinical presentation - Adults (Typical s/s)
Fever Pain Lethargy Malaise Swelling of infected site
Clinical presentation - Adults (hx of fx)
Drainage or delay in fx healing
Clinical presentation - Classic signs
Fever Erythema Soft tissue swelling Bone pain Decreased ROM Ulcers
Dx work-up - labs in general
CBC
CRP
ESR
CBC
Leukocytosis acutely
Chronically WBC may be normal
CRP
Marker of inflammation
Elevated in both acute and chronic osteomyelitis
ESR
Marker of inflammation
Elevated in both acute and chronic osteomyelitis
Dx work-up - imaging in general
Plain radiographs
MRI
Bone scan
CT
Dx work-up - plain radiographs
Focal osteopenia Soft tissue swelling Loss of tissue planes Erosion of bone Alteration of cancellous bone Periosteal elevation Focal lucency around sx implants Sensitivity 14% Takes about 2 weeks to show up
Dx work-up - MRI
Marrow changes associated with osteomyelitis
Determines extent of soft tissue involvement
Can detect osteomyelitis within 3-5d
Dx work-up - Bone scan
Three-phase technetium-99 bone scintigraphy with leukocyte scintigraphy positive within a few days
High sensitivity
Low specificity
Dx work-up - CT
Cortical bony details
Detects presence of early cortical erosions associated with osteomyelitis
Dx work-up - Gold standard
Open bx or aspiration prior to abx administration
Exception - those with hematogenous osteomyelitis and positive blood cultures
Dx work-up is not enough, so
Look for soft tissue or wound culture typically polymicrobial involvement
Chronic osteomyelitis - imaging
Plain radiography
MRI
Bone scintigraphy
Demonstrating contiguous soft tissue infection or bony destruction
Chronic osteomyelitis - clinical s/s
Exposed bone Persistent sinus tract Tissue necrosis overlying bone Chronic wound overlying sx hardware Chronic wound overlying fx
Chronic osteomyelitis - lab eval
Positive blood cultures
Elevated C-reactive protein level
Elevated erythrocyte sed rate
Chronic osteomyelitis - definitive dx
Bone bx with bacterial culture
DDX
Neuropathic arthropathy - Charcot arthropathy Tumors Fx and other lytic lesions Suppurative arthritis Rheumatic fever Cellulitis Gout Bursitis
Tx - in general
Refer to ortho & infectious dz
Sx debridement
Abx therapy
Tx - sx debridement
Sx removal of necrotic tissue
Abx impregnated beads
Vertebral body osteo and epidural abscess - urgent neuro-sx decompression
Tx - abx therapy
Based on results of cultures and sensitivity
If clinically possible - DELAY ABX UNTIL CULTURES OBTAINED
Typically IV abx followed by oral abx
Tx - chronic osteomyelitis
IV abx for 2-6 weeks with transition to oral abx for total tx of 4-8 weeks
Tx - empiric tx of acute osteomyelitis
Beta-lactam abx
If MRSA suspected, then IV vancomycin
In DM foot infections or PCN allergy - Fluroquinolone
Oral therapy with quinolone (Cipro 750 mg BID for 6-8w) has been shown as effective as parenteral.
- if S. aureus quinolones are combined with rifampin 30 mg PO BID
Prognosis
Most pts can be tx successfully with sx and abx therapy
Complications
5-33% refractory to tx
Usually due to pt’s overall medical status, comorbidities
May need long-term suppressive abx therapy
Amputation in some cases
Extension to surrounding bone can complicate acute osteomyelitis
Recurrence redsults in anemia, elevated ESR, wight loss, weakness and rarely amyloidosis or nephrotic syndrome
Squamous cell carcinoma or fibrosarcoma may arise in persistently infected tissues
