Updated: 7/2/2019

Osteomyelitis

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Snapshot
  • A 52-year-old man presents to the emergency department for fever, chills, and pain in the left foot. His symptoms progessively worsened over the course of a week. Medical history is significant for poorly controlled type II diabetes mellitus. On physical exam, there is tenderness to palpation of the left foot. Laboratory testing is significant for an elevated erythrocyte sedimentation rate and C-reactive protein; as well as, a leukocytosis. A plain radiograph demonstrates periosteal thickening and soft tissue swelling.
Introduction
  • Clinical definition
    • inflammation of the bone and bone marrow most commonly due secondarily to infection that can be categorized as
      • acute osteomyelitis
        • more common in children
        • typically symptom onset is within 2 weeks postinfection
      • chronic osteomyelitis
        • more common in adults
        • typically symptoms persists months or years postinfection
  • Epidemiology
    • risk factors
      • diabetes
      • peripheral vascular disease
      • open fracture
      • intravenous drug use
      • catheter use
      • surgery
  • Etiology
    • note that infection can be due to bacteria, fungi, and mycobacteria
    • microbiology
      • Staphylococcus aureus 
        • most common cause overall (including pediatric patients) 
          • may be seen in
            • sickle cell disease
            • prosthetic joint replacement
            • vertebral involvement 
              • focal back pain/tenderness
            • intravenous drug use
      • Neisseria gonorrhoeae
        • rare
      • Staphylococcus epidermidis
        • can also be seen in prosthetic joint involvement
      • Mycobacterium tuberculosis
        • can also be seen in cases of vertebral involvement (Pott disease)
      • Pasteurella multocida
        • seen in cases caused by cat and dog bites
      • Pseudomonas and Candida
        • can also be seen in cases caused by intravenous drug abuse
  • Pathogenesis
    • hematogenous seeding of bone
    • contiguous spread of infection from adjacent structures (e.g., soft tissues and joints)
    • direct inoculation
      • e.g., penetrating trauma and contaminated surgical tools
  • Prognosis
    • mortality has significantly decreased since the use of antibiotics
Presentation
  • Symptoms
    • acute osteomyelitis
      • lethargy
      • acute pain in affected site
      • erythema and
    • chronic osteomyelitis
      • chronic pain
  • Physical exam
    • swelling
    • erythema
    • tenderness
    • reduced range of motion
    • bone tenderness
    • ulcers
    • exposed bone may be seen
    • sinus tract
      • pathognomonic for chronic osteomyelitis
    • must perform a neurovascular exam
Imaging
  • Radiographs
    • indication
      • preferred initial test in evaluating for osteomyelitis
        • note that it takes 10-14 days postinfection for findings to appear
    • findings
      • periosteal thickening and elevation "Codman triangle"
  • Magnetic resonance imaging 
    • indication
      • considered when radiography is unrevealing
    • findigs
      • may reveal bone necrosis, abscess, and sinus tracts
Studies
  • Labs
    • C-reactive protein 
    • erythrocyte sedimentation rate
    • leukocytosis
      • present in acute osteomyelitis
      • unlikely to be found in chronic osteomyelitis
  • Biopsy and culture 
    • confirms the diagnosis
Differential
  • Septic arthritis
  • Gout
  • Cellulitis
  • Osteosarcoma
Treatment
  • Medical
    • empiric antibiotics
      • indication
        • considered the mainstay of treatment
          • eventually tailored to organism after culture sensitivities return
  • Operative
    • debridement
      • indication
        • to remove necrotic tissue
Complications
  • Bone necrosis
  • Sepsis
  • Squamous cell carcinoma
    • most common tumor associated with osteomyelitis
 

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Questions (5)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M2.OR.4679) A 55-year-old obese woman is admitted to your floor for chronic fevers. She states she has had fevers of of over 101F as measured on her oral thermometer for the past month. Her vitals are T 100.9 F, HR 95 and regular, RR 16, BP 150/95. On history she states that she has a history of diabetes and is noncompliant with her insulin. She was recently treated for a foot infection with antibiotics, but her fevers have remained. Her last HbA1C was 8.5%. On exam, the patient has no gross deficits, but does admit to pain in her left lower leg and foot. Physical exam reveals a Grade IV ulcer, as displayed in Figure A. She states she has severe pain when bearing weight on her left leg. Otherwise, all extremities have diminished pulses and sensation. There is no erythema in the surrounding area and no areas of fluctuance. Figure B shows AP and lateral radiographs of the patient's left leg. What is the most likely diagnosis? Review Topic | Tested Concept

QID: 107280
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Osteomyelitis

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Charcot joint

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M2 A

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(M3.OR.56) A 66-year-old man presents to his primary care physician complaining of increasing discharge from a lesion on his foot. He noticed it a month ago and states it has been gradually worsening. He has a long history of poorly controlled diabetes with complications including chronic renal failure and peripheral neuropathy. He denies any pain or fevers/chills. Physical exam is notable for the finding in Figure A. Laboratory evaluation is significant for an erythrocyte sedimentation rate of 226 mm/h. Which of the following would be the most accurate imaging test for this patient's condition? Review Topic | Tested Concept

QID: 102997
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M2 D

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(M2.OR.28) A 45-year-old woman with a history of diabetes presents with 1 week of progressively worsening back pain and subjective fevers. Six months ago, she was treated for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, thought to be secondary to an infected diabetic foot ulcer. There was no inciting trauma for the back pain, and she has no urinary incontinence or altered sensation in her back or legs. Her temperature is 101.3°F (38.5°C), blood pressure is 157/99 mm Hg, pulse is 100/min, respirations are 17/min, and oxygen saturation is 98% on room air. She has point tenderness in her back at the L4 level but no apparent swelling or overlying erythema. Her left foot has the findings depicted in Figure A. Which of the following is the most accurate test for this patient's back pain? Review Topic | Tested Concept

QID: 104913
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M2 D

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