Updated: 12/15/2018

Supracondylar Humerus Fracture

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Snapshot
  • An 8-year-old boy falls from a tree and lands on his outstretched right hand. He immediately develops severe elbow pain and swelling. On exam, he is unable to flex or extend his elbow due to pain. Elbow radiograph is shown and demonstrates a dorsally displaced supracondylar humerus fracture.
Introduction
  • Clinical definition
    • fracture of the distal humerus proximal to the medial and lateral condyles
  • Epidemiology
    • incidence
      • most common pediatric elbow fracture
      • accounts for 41% of all serious pediatric elbow injuries
      • extension type injury most common (95-98%)
    • demographics
      • children aged 5-7 years of age
      • rare in adults
      • males and females equally likely
  • Etiology
    • accidental trauma (e.g., fall from moderate height)
      • fall on outstretched hand
        • leads to a extension type injury
      • fall on posterior elbow
        • leads to a flexion type injury
  • Pathoanatomy
    • normal anatomy
      • humerus articulates with the radius and ulna at the elbow joint
      • medial and lateral condyles are located at the distal portion of the humerus
        • condyles represent the medial and lateral columns of the distal expansion of the humerus
      • supracondylar humerus is the part of the humerus just proximal to the medial and lateral condyles
    • fracture mechanics
      • in an extension type injury, the olecranon process is forced against the weaker metaphyseal bone of the supracondylar humerus
        • distal fracture fragment will be angulated and/or displaced posteriorly 
      • in a flexion type injury, a direct blow to the posterior elbow forces the distal condylar bone to displace anteriorly
        • distal fracture fragment will be angulated and/or displaced anteriorly 
  • Associated conditions
    • neurapraxia
      • anterior interosseous nerve (AIN) neurapraxia 
        • branch of median nerve
          • innervates flexor pollicis longus, pronator quadratus, and lateral half of flexor digitorum profundus
        • most common neurapraxia in extension type fractures
      • radial nerve neurapraxia
        • second most common neurapraxia in extension type fractures
      • ulnar nerve neurapraxia
        • most common neurapraxia in flexion type fractures
  • Prognosis
    • favorable
      • non-displaced or minimally displaced fractures
    • negative
      • poor anatomic reduction
      • vascular injury
Presentation
  • Symptoms
    • elbow pain and limited range of motion
  • Physical exam
    • inspection
      • gross deformity only in severe cases
      • swelling
      • ecchymosis
    • palpation
      • tender to palpation
    • motion
      • limited flexion and extension
      • pain with passive movement
    • neurologic exam
      • important to assess motor and sensory nerve function
        • AIN neurapraxia
          • unable to flex the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger (can't make A-OK sign)
        • radial nerve neurapraxia
          • inability to extend wrist or digits
    • vascular exam
      • important to assess for vascular insufficiency
        • cold, pale, and pulseless hand necessitates immediate reduction and pinning
        • if hand is still dysvascular after reduction and pinning it may require vascular exploration
Imaging
  • Radiographs 
    • indication
      • anteroposterior (AP) and lateral radiographs always indicated if fracture is suspected
    • findings
      • fracture line may or may not be present
      • anterior fat pad sign (sail sign) and posterior fat pad sign 
        • joint effusion suggestive of fracture
Treatment
  • Conservative
    • long arm posterior splint followed by long arm casting
      • indications
        • non-displaced fractures
        • minimally displaced fractures with no comminution and minimal swelling
  • Operative
    • closed reduction and percutaneous pinning
      • indications
        • displaced fractures
        • flexion type fractures
        • dysvascular hand
Differential
  • Radial head subluxation (Nursemaid's elbow) 
    • second most common pediatric elbow injury
    • arm held in flexion and pronation
    • commonly occurs due to excessive traction and not a fall
  • Lateral epicondyle fracture
    • third most common pediatric elbow injury
    • second most common pediatric elbow fracture
    • will be tender on lateral side with minimal tenderness on medial side
Complications
  • Malunion
    • cubitus varus (gunstock deformity)
      • malalignment resulting in change from physiologic valgus elbow alignment to varus alignment
      • cosmetic deformity with minimal functional impairment
  • Vascular injury
    • Volkmann ischemic contracture 
      • damage to brachial artery leads to volar compartment syndrome and muscle necrosis
      • irreversible muscle contractures in the forearm, wrist, and hand
 

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Questions (1)
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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