Courtesy: Dr. Salil Upasani, Ashok Shyam, IORG, OrthoTV
Pediatric Elbow X-ray – Quick Orthopedic Notes
1. Why Pediatric Elbow X-ray is Difficult
- Multiple secondary ossification centers
- Large cartilaginous component not visible on X-ray
- Ossification centers appear at different ages
2. Ossification Centers (CRITOE) – Must Know
Elbow ossification centers CRITOE
Order of Appearance
- Capitellum: ~1 year
- Radial head: ~3 years
- Medial epicondyle: ~5 years
- Trochlea: ~7 years
- Olecranon: ~9 years
- Lateral epicondyle: ~11 years
Clinical Importance
- Differentiates normal ossification centers from fracture fragments
3. First Step: Clinical Examination
Local Examination
- Swelling and ecchymosis
- Skin puckering suggests severe injury
- Localized tenderness
Neurovascular Assessment
- Radial nerve: thumb extension
- Median nerve: thumb flexion
- Ulnar nerve: finger abduction/adduction
- Capillary refill and distal perfusion
4. X-ray Quality: Do Not Accept Poor Imaging
Required Views
- Proper anteroposterior view
- True lateral view
Avoid
- Flexed elbow anteroposterior view, which is unreliable
Recommended Actions
- Repeat imaging if inadequate
- Obtain comparison view of the opposite elbow
- Use oblique views when required
5. Key Radiological Lines and Angles
A. Baumann’s Angle (AP View)
- Formed between humeral shaft and capitellar physis
- Assesses varus or valgus alignment
B. Anterior Humeral Line (Lateral View)
- Drawn along anterior cortex of humerus
Normal
- Passes through middle third of capitellum
Abnormal
- Passes anterior to capitellum
- Suggests extension-type supracondylar fracture
C. Humeral Shaft–Capitellar Angle
- Normal range: 30 to 40 degrees
- Increased extension suggests injury
6. Fat Pad Sign (Indicator of Occult Fracture)
Anterior Fat Pad
- Small and parallel to humerus may be normal
- Elevated triangular shape indicates abnormality
Posterior Fat Pad
- Normally not visible
- Visibility always indicates pathology
Clinical Implication
- Suggests occult fracture
Common Associated Fractures
- Supracondylar fracture of humerus
- Radial neck fracture
- Lateral condyle fracture of humerus
- Proximal ulna fractures
7. Radiocapitellar Alignment
Rule
- A line along the radial shaft must intersect the capitellum in all views
If Not Aligned
- Suspect:
- Radial head dislocation
- Monteggia fracture-dislocation
8. Common Pediatric Elbow Injuries
- Supracondylar fracture (most common)
- Lateral condyle fracture
- Radial neck fracture
- Proximal ulna fracture
- Transphyseal distal humerus fracture
- Elbow dislocation (less common)
9. Role of Ultrasound
Use
- Helpful in lateral condyle fractures
Findings
- Intact cartilage suggests stability and suitability for casting
- Cartilage disruption indicates higher risk of displacement and need for surgery
10. Transphyseal Distal Humerus Fracture
Key Features
- Seen in very young children
- Difficult to diagnose on X-ray due to cartilaginous structures
Clue
- Radius and ulna are not aligned with humerus
Confirmation
- MRI
- Arthrogram
11. Systematic Approach to Pediatric Elbow X-ray
- Correlate with clinical findings
- Ensure good quality imaging
- Identify ossification centers using CRITOE
- Assess:
- Anterior humeral line
- Radiocapitellar line
- Baumann’s angle
- Look for:
- Fat pad sign
- Alignment abnormalities
- Form differential diagnosis
- Use advanced imaging if required
12. Key Exam Pearls
- Posterior fat pad indicates occult fracture
- Radiocapitellar line must intersect capitellum in all views
- CRITOE sequence is essential for age-based interpretation
- Poor quality X-rays must be repeated
- Most common fracture is supracondylar fracture
- Comparison views are often helpful
Final Takeaway
- Pediatric elbow X-ray interpretation requires:
- Knowledge of ossification timing
- Systematic evaluation
- Strong clinical correlation
- Missing subtle findings can result in:
- Malunion
- Deformity
- Functional impairment
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