DESCRIPTION
Osteomyelitis (OM): Infection of bone with ongoing inflammatory destruction
Usually bacterial, but fungal OM does occur
Could be acute or chronic
ETIOLOGY
Hematogenous OM:
Primarily in children, elderly, IV drug abuse (IVDA) patients
Seeding of bacteria to bone from remote site of infection via bloodstream
Children have acute OM and adults subacute or chronic.
Hematogenous OM of long bones rarely occurs in adults.
Most children with acute hematogenous OM have no preceding illness.
1/3 have history of trauma to affected area.
Staphylococcus aureus is most common cause of OM in all ages.
Neonates: S. aureus, Enterobacteriaceae, group A and B streptococci, and Escherichia coli
Children: S. aureus, group A streptococci, Haemophilus influenzae, Enterobacteriaceae
Salmonella: Common in sickle cell disease
Adults: S. aureus, Enterobacteriaceae, Pseudomonas, gram-negative rods, Staphylococcus epidermidis, gram-positive anaerobes, especially Peptostreptococcus
Illicit drug users: Candida, Pseudomonas, Serratia marcescens
Prolonged neutropenia: Candida, Aspergillus, Rhizopus, Blastomyces, coccidioidomycosis
Hematogenous vertebral OM:
Uncommon
Most prevalent in adults >45
Involves the disk and vertebra above and below
Often in setting of long-term urinary catheter placement, IVDA, cancer, hemodialysis, or diabetes
IVDA: OM of pubic symphysis, sternoclavicular, and sacroiliac (S-I) joints
Lumbar vertebrae most common, followed by thoracic, then cervical
Posterior extension leads to epidural/subdural abscess or meningitis.
Anterior extension may lead to paravertebral, retropharyngeal, mediastinal, subphrenic, retroperitoneal, or psoas abscess.
Direct or contiguous OM:
Organism(s) directly seeded in bone due to trauma, especially following open fractures:
Spread from adjacent site of infection or from surgery
More common in adults and adolescents
S. aureus, Enterobacteriaceae, Pseudomonas
Normal vascularity:
S. aureus and S. epidermidis, gram-negative bacilli, and anaerobic organisms
Vascular insufficiency/diabetes:
Small bones of feet are common sites.
Infection resulting from minor trauma, infected nail beds, cellulitis, or skin ulceration
Polymicrobial, including anaerobes
Puncture wound through tennis shoe: S. aureus, Pseudomonas
Clavicular OM can occur as complication of subclavian vein catheterization.
Chronic OM:
Osteomyelitis that persists or recurs
Distinguishing characteristic is necrotic bone (sequestrum) that must be debrided.
S. epidermidis, S. aureus, Pseudomonas aeruginosa, Serratia marcescens, and E. coli
DIAGNOSIS
SIGNS AND SYMPTOMS
Vary with duration of disease
History
Mainly nonspecific symptoms
Pain: Localized, deep, dull, and throbbing; occurs with and without movement
Fever and chills; may be absent in chronic OM
Malaise, nausea, vomiting
Reluctance to use extremity
Nonhealing ulcers despite proper therapy
Consider OM as a cause of fracture nonunion
Predisposing factors: DM, vasculopathy, IVDA, invasive procedures, trauma
Physical Exam
Tenderness to palpation, warmth, erythema, edema, decreased range of motion
Drainage of sinus tract
Deep ulcers and palpable bone (+ “probe to bone” test has very high positive predictive value)
If ulcer size >2 cm2 and >3 mm in depth, bone involvement is likely.
ESSENTIAL WORKUP
CBC
ESR and C-reactive protein
Radiographs
Blood and wound cultures and sensitivities
DIAGNOSTIC TESTS & INTERPRETATION
Lab
CBC; WBC may be elevated but often normal
ESR; elevated in >90% of cases
C-reactive protein (usually elevated)
Blood cultures (positive in ~50% of cases)
Imaging
Plays a central role in evaluation
Start with plain films; other tests often required
Radiographs:
May be normal for the 1st 2–3 wk of symptoms
Earliest finding is periosteal elevation, followed by cortical erosions, then new bone formation.
40–50% of focal bone loss needed to detect lucency on radiograph; fewer than 1/3 of cases have diagnostic findings at 10 days
Obtain CXR if TB suspected
MRI:
Best modality to obtain detailed anatomy and extension of soft-tissue and bone narrow involvement
Sensitivity and specificity of ~90%
Reveals bone edema, cortical destruction, periosteal reaction, joint surface damage, and soft-tissue involvement before x-rays
Effective in early detection (3–5 days from onset of infection)
Test of choice to identify vertebral OM and OM in diabetic foot ulcers
Occasional false-positive results in trauma, previous surgical procedures, or neuropathic joint disease
Negative study after 1 wk of symptoms rules out acute OM
CT:
Modality of choice when MRI can’t be done
Reveals bone edema, cortical destruction, periosteal reaction, small foci of gas or foreign bodies, joint surface damage, and soft-tissue involvement when plain films not helpful
Useful in OM of vertebrae, sternum, calcaneus, pelvic bones
Useful to surgeons in guiding debridement and biopsy
Bone scan:
Technetium99m methylene diphosphonate (99mTc-MDP)
Measures increase in bone metabolic activity
~95% sensitive but less specific than MRI
Bone scan abnormal after 2–3 days of symptoms
False-positive may occur in trauma, surgery, chronic soft-tissue infection, tumor
High radiation burden, useful if suspect multifocal disease
Leukocyte scintigraphy:
Indium111-labeled WBCs
More specific but less sensitive than bone scan
Difficult to distinguish bone inflammation from soft-tissue inflammation (ie, cellulitis, tumors, inflammatory arthritis)
US:
An emerging modality for OM especially in children
Periosteal elevation or thickening, fluid collections adjacent to bone often seen
May show findings of OM days prior to plain films
Useful in guiding biopsy
Diagnostic Procedures/Surgery
Gold standard for diagnosis is bone biopsy with histology and tissue Gram stains, including culture and sensitivities.
Needle aspiration has lower sensitivity than open biopsy.
Culture of sinus or drainage from wound can be misleading; correlates well with S. aureus, but not as reliable for other organisms.
Pediatric Considerations
70–85% of children have fever higher than 38.5°C.
Neonates are commonly afebrile.
Only ~1 in 3 of children will have leukocytosis.
Blood cultures positive in ~50%
US
DIFFERENTIAL DIAGNOSIS
Cellulitis
Paronychia/felon
Bursitis, toxic synovitis, septic arthritis
Extremity fracture
Bone infarction in sickle cell patients
Acute leukemia, malignant bone tumors
Mechanical back pain
Spinal epidural abscess
Brucellosis, especially in S-I joint
TB, more common in thoracic spine (Pott disease)
TREATMENT
INITIAL STABILIZATION/THERAPY
Emergent stabilization if septic or if neurologic deficits from spine involvement
ED TREATMENT/PROCEDURES
Empiric antibiotic treatment in ED
Cultures should guide subsequent antibiotic regimen.
Antibiotics: Depend on patient’s age and organism (see Medications section)
Orthopedic and infectious disease consultation
Surgical intervention may be needed to optimize treatment (eg, infected fracture or hardware, bone necrosis).
Parenteral antibiotic treatment for 4–6 wk
MEDICATION
Newborn–4 mo: Penicillinase-resistant synthetic penicillin (eg, nafcillin: 37 mg/kg IV q6h) plus a 3rd-generation cephalosporin (eg, ceftriaxone: 50–75 mg/kg/d IV); if suspect methicillin-resistant S. aureus (MRSA) then vancomycin (40–60 mg/kg IV q6h) plus a 3rd-generation cephalosporin. (Note: Doses are based on age >28 days)
Children (>4 mo): Penicillinase-resistant synthetic penicillin (eg, nafcillin: 37 mg/kg IV q6h to max. 8–12 g/d). If suspect MRSA, then vancomycin (40–60 mg/kg IV q6h to max. 2–4 g/d). Add 3rd-generation cephalosporin if suspicion for gram-negative rods, or presence on Gram stain noted (eg, ceftriaxone: 50–75 mg/kg IV per day to max. 2–4 g/d)
Adult: Penicillinase-resistant synthetic penicillin (eg, nafcillin: 2 g IV q4h); if suspect MRSA, vancomycin (15 mg/kg IV q12h)
Sickle cell anemia with OM: Ciprofloxacin 400 mg IV q12h, or levofloxacin 750 mg IV q24h (not in children); alternative: 3rd-generation cephalosporin
Post–nail puncture through tennis shoe: Ciprofloxacin 750 mg PO b.i.d. or levofloxacin 750 mg PO q24h; alternative: Ceftazidime 2 g IV q8h
Involving orthopedic prosthesis or hardware: Add rifampin (10 mg/kg/d PO/IV to maximum of 600 mg/d) to regimen for S. aureus. Hardware removal generally required.
Post-traumatic OM: Vancomycin and ceftazidime
If vancomycin-resistant enterococcus present: Linezolid 600 mg IV q12h × 6 wk
Pediatric Considerations
Children with hematogenous OM may undergo short-course IV antibiotics and then be changed to oral for additional 1–2 mo.
FOLLOW-UP
DISPOSITION
Admission Criteria
Patients with acute OM should be admitted.
Patients with chronic osteomyelitis usually require admission for surgical procedures, debridement, and obtaining bone cultures and histology.
Discharge Criteria
Subacute or chronic OM patients may be considered for outpatient management if home IV antibiotics arranged, bone specimens obtained, and necrotic bone debrided.
Cases refractory to debridement and antibiotics benefit from hyperbaric oxygen as an adjunct to standard treatment.
~2/3 of these cases will demonstrate benefit.
PEARLS AND PITFALLS
WBC may be normal in many cases.
Radiographs may be normal in the 1st 2–3 wk of symptoms.
Wound cultures are low yield in guiding antibiotic therapy.
Ref-(Thanks to)
Rosen & Barkin’s 5-Minute
Emergency Medicine Consult
by Jeffrey J. Schaider, Roger M. Barkin, Stephen R. Hayden, Richard
E. Wolfe, Adam Z. Barkin, Philip Shayne, and Peter Rosen
4th edition published by Wolters Kluwer
This article is meant exclusively as a learning resource to MBBS students. My sincere thanks to the author & Publisher.There is no commercial interest involved.Purpose is to familiarize the students to such good publications
Osteomyelitis (OM): Infection of bone with ongoing inflammatory destruction
Usually bacterial, but fungal OM does occur
Could be acute or chronic
ETIOLOGY
Hematogenous OM:
Primarily in children, elderly, IV drug abuse (IVDA) patients
Seeding of bacteria to bone from remote site of infection via bloodstream
Children have acute OM and adults subacute or chronic.
Hematogenous OM of long bones rarely occurs in adults.
Most children with acute hematogenous OM have no preceding illness.
1/3 have history of trauma to affected area.
Staphylococcus aureus is most common cause of OM in all ages.
Neonates: S. aureus, Enterobacteriaceae, group A and B streptococci, and Escherichia coli
Children: S. aureus, group A streptococci, Haemophilus influenzae, Enterobacteriaceae
Salmonella: Common in sickle cell disease
Adults: S. aureus, Enterobacteriaceae, Pseudomonas, gram-negative rods, Staphylococcus epidermidis, gram-positive anaerobes, especially Peptostreptococcus
Illicit drug users: Candida, Pseudomonas, Serratia marcescens
Prolonged neutropenia: Candida, Aspergillus, Rhizopus, Blastomyces, coccidioidomycosis
Hematogenous vertebral OM:
Uncommon
Most prevalent in adults >45
Involves the disk and vertebra above and below
Often in setting of long-term urinary catheter placement, IVDA, cancer, hemodialysis, or diabetes
IVDA: OM of pubic symphysis, sternoclavicular, and sacroiliac (S-I) joints
Lumbar vertebrae most common, followed by thoracic, then cervical
Posterior extension leads to epidural/subdural abscess or meningitis.
Anterior extension may lead to paravertebral, retropharyngeal, mediastinal, subphrenic, retroperitoneal, or psoas abscess.
Direct or contiguous OM:
Organism(s) directly seeded in bone due to trauma, especially following open fractures:
Spread from adjacent site of infection or from surgery
More common in adults and adolescents
S. aureus, Enterobacteriaceae, Pseudomonas
Normal vascularity:
S. aureus and S. epidermidis, gram-negative bacilli, and anaerobic organisms
Vascular insufficiency/diabetes:
Small bones of feet are common sites.
Infection resulting from minor trauma, infected nail beds, cellulitis, or skin ulceration
Polymicrobial, including anaerobes
Puncture wound through tennis shoe: S. aureus, Pseudomonas
Clavicular OM can occur as complication of subclavian vein catheterization.
Chronic OM:
Osteomyelitis that persists or recurs
Distinguishing characteristic is necrotic bone (sequestrum) that must be debrided.
S. epidermidis, S. aureus, Pseudomonas aeruginosa, Serratia marcescens, and E. coli
DIAGNOSIS
SIGNS AND SYMPTOMS
Vary with duration of disease
History
Mainly nonspecific symptoms
Pain: Localized, deep, dull, and throbbing; occurs with and without movement
Fever and chills; may be absent in chronic OM
Malaise, nausea, vomiting
Reluctance to use extremity
Nonhealing ulcers despite proper therapy
Consider OM as a cause of fracture nonunion
Predisposing factors: DM, vasculopathy, IVDA, invasive procedures, trauma
Physical Exam
Tenderness to palpation, warmth, erythema, edema, decreased range of motion
Drainage of sinus tract
Deep ulcers and palpable bone (+ “probe to bone” test has very high positive predictive value)
If ulcer size >2 cm2 and >3 mm in depth, bone involvement is likely.
ESSENTIAL WORKUP
CBC
ESR and C-reactive protein
Radiographs
Blood and wound cultures and sensitivities
DIAGNOSTIC TESTS & INTERPRETATION
Lab
CBC; WBC may be elevated but often normal
ESR; elevated in >90% of cases
C-reactive protein (usually elevated)
Blood cultures (positive in ~50% of cases)
Imaging
Plays a central role in evaluation
Start with plain films; other tests often required
Radiographs:
May be normal for the 1st 2–3 wk of symptoms
Earliest finding is periosteal elevation, followed by cortical erosions, then new bone formation.
40–50% of focal bone loss needed to detect lucency on radiograph; fewer than 1/3 of cases have diagnostic findings at 10 days
Obtain CXR if TB suspected
MRI:
Best modality to obtain detailed anatomy and extension of soft-tissue and bone narrow involvement
Sensitivity and specificity of ~90%
Reveals bone edema, cortical destruction, periosteal reaction, joint surface damage, and soft-tissue involvement before x-rays
Effective in early detection (3–5 days from onset of infection)
Test of choice to identify vertebral OM and OM in diabetic foot ulcers
Occasional false-positive results in trauma, previous surgical procedures, or neuropathic joint disease
Negative study after 1 wk of symptoms rules out acute OM
CT:
Modality of choice when MRI can’t be done
Reveals bone edema, cortical destruction, periosteal reaction, small foci of gas or foreign bodies, joint surface damage, and soft-tissue involvement when plain films not helpful
Useful in OM of vertebrae, sternum, calcaneus, pelvic bones
Useful to surgeons in guiding debridement and biopsy
Bone scan:
Technetium99m methylene diphosphonate (99mTc-MDP)
Measures increase in bone metabolic activity
~95% sensitive but less specific than MRI
Bone scan abnormal after 2–3 days of symptoms
False-positive may occur in trauma, surgery, chronic soft-tissue infection, tumor
High radiation burden, useful if suspect multifocal disease
Leukocyte scintigraphy:
Indium111-labeled WBCs
More specific but less sensitive than bone scan
Difficult to distinguish bone inflammation from soft-tissue inflammation (ie, cellulitis, tumors, inflammatory arthritis)
US:
An emerging modality for OM especially in children
Periosteal elevation or thickening, fluid collections adjacent to bone often seen
May show findings of OM days prior to plain films
Useful in guiding biopsy
Diagnostic Procedures/Surgery
Gold standard for diagnosis is bone biopsy with histology and tissue Gram stains, including culture and sensitivities.
Needle aspiration has lower sensitivity than open biopsy.
Culture of sinus or drainage from wound can be misleading; correlates well with S. aureus, but not as reliable for other organisms.
Pediatric Considerations
70–85% of children have fever higher than 38.5°C.
Neonates are commonly afebrile.
Only ~1 in 3 of children will have leukocytosis.
Blood cultures positive in ~50%
US
DIFFERENTIAL DIAGNOSIS
Cellulitis
Paronychia/felon
Bursitis, toxic synovitis, septic arthritis
Extremity fracture
Bone infarction in sickle cell patients
Acute leukemia, malignant bone tumors
Mechanical back pain
Spinal epidural abscess
Brucellosis, especially in S-I joint
TB, more common in thoracic spine (Pott disease)
TREATMENT
INITIAL STABILIZATION/THERAPY
Emergent stabilization if septic or if neurologic deficits from spine involvement
ED TREATMENT/PROCEDURES
Empiric antibiotic treatment in ED
Cultures should guide subsequent antibiotic regimen.
Antibiotics: Depend on patient’s age and organism (see Medications section)
Orthopedic and infectious disease consultation
Surgical intervention may be needed to optimize treatment (eg, infected fracture or hardware, bone necrosis).
Parenteral antibiotic treatment for 4–6 wk
MEDICATION
Newborn–4 mo: Penicillinase-resistant synthetic penicillin (eg, nafcillin: 37 mg/kg IV q6h) plus a 3rd-generation cephalosporin (eg, ceftriaxone: 50–75 mg/kg/d IV); if suspect methicillin-resistant S. aureus (MRSA) then vancomycin (40–60 mg/kg IV q6h) plus a 3rd-generation cephalosporin. (Note: Doses are based on age >28 days)
Children (>4 mo): Penicillinase-resistant synthetic penicillin (eg, nafcillin: 37 mg/kg IV q6h to max. 8–12 g/d). If suspect MRSA, then vancomycin (40–60 mg/kg IV q6h to max. 2–4 g/d). Add 3rd-generation cephalosporin if suspicion for gram-negative rods, or presence on Gram stain noted (eg, ceftriaxone: 50–75 mg/kg IV per day to max. 2–4 g/d)
Adult: Penicillinase-resistant synthetic penicillin (eg, nafcillin: 2 g IV q4h); if suspect MRSA, vancomycin (15 mg/kg IV q12h)
Sickle cell anemia with OM: Ciprofloxacin 400 mg IV q12h, or levofloxacin 750 mg IV q24h (not in children); alternative: 3rd-generation cephalosporin
Post–nail puncture through tennis shoe: Ciprofloxacin 750 mg PO b.i.d. or levofloxacin 750 mg PO q24h; alternative: Ceftazidime 2 g IV q8h
Involving orthopedic prosthesis or hardware: Add rifampin (10 mg/kg/d PO/IV to maximum of 600 mg/d) to regimen for S. aureus. Hardware removal generally required.
Post-traumatic OM: Vancomycin and ceftazidime
If vancomycin-resistant enterococcus present: Linezolid 600 mg IV q12h × 6 wk
Pediatric Considerations
Children with hematogenous OM may undergo short-course IV antibiotics and then be changed to oral for additional 1–2 mo.
FOLLOW-UP
DISPOSITION
Admission Criteria
Patients with acute OM should be admitted.
Patients with chronic osteomyelitis usually require admission for surgical procedures, debridement, and obtaining bone cultures and histology.
Discharge Criteria
Subacute or chronic OM patients may be considered for outpatient management if home IV antibiotics arranged, bone specimens obtained, and necrotic bone debrided.
Cases refractory to debridement and antibiotics benefit from hyperbaric oxygen as an adjunct to standard treatment.
~2/3 of these cases will demonstrate benefit.
PEARLS AND PITFALLS
WBC may be normal in many cases.
Radiographs may be normal in the 1st 2–3 wk of symptoms.
Wound cultures are low yield in guiding antibiotic therapy.
Ref-(Thanks to)
