Diagnosis: Extension-Type Supracondylar Fracture of the Left Humerus (Pediatric)

Radiographic Findings

• Posterior displacement/angulation of the distal humeral fragment is visible
• The anterior humeral line (a line drawn down the anterior cortex of the humerus on a true lateral) fails to bisect the middle third of the capitellum - instead it passes anterior to or through only the anterior third of the capitellum, indicating posterior displacement of the distal fragment
• This is the classic radiographic sign of an extension-type supracondylar fracture
• A posterior fat pad sign may also be present (indirect sign of intra-articular effusion/hemorrhage)

• The distal humeral metaphysis shows a transverse fracture line at the supracondylar level
• Disruption of the normal flaring of the distal humerus
• The Baumann angle (normally 70-75 degrees) appears altered, consistent with displacement

Diagnosis

Extension-type Supracondylar Fracture of the Humerus (Left) Most likely Gartland Type II or III based on visible displacement

Why This Injury in a 6-Year-Old?

Urgent Assessment Required

• Radial pulse (brachial artery at risk - runs anterior to the fracture site)
• Median nerve (most commonly injured in extension-type fractures - check thumb opposition and palmar sensation)
• Anterior interosseous nerve (AIN palsy: inability to make "OK sign" - cannot flex thumb IP + index DIP)
• Watch for 5 Ps: Pain, Pallor, Pulselessness, Paralysis, Paresthesia - signs of Volkmann ischemic contracture

Management

Disclaimer: This is an AI-assisted radiological interpretation for educational purposes. All clinical decisions must be confirmed by a qualified radiologist and/or orthopedic surgeon who can evaluate the patient directly.

Diagnosis: Posterior Dislocation of the Left Elbow

Radiographic Findings

• The radius and ulna are displaced posteriorly relative to the distal humerus
• The olecranon has moved posterior and superior, sitting behind the trochlea
• The normal articulation between the trochlear notch and trochlea is lost
• The elbow is held in approximately 45 degrees of flexion
• The capitellum and radial head are no longer in their normal articulating positions

• The radius and ulna are displaced posteriorly and slightly laterally (most common - posterolateral type)
• The normal "carrying angle" alignment is disrupted
• The distal humerus condyles are overlapping the proximal forearm bones
• Must carefully assess for associated fractures of the coronoid process, radial head, and medial epicondyle

Diagnosis

Posterior (Posterolateral) Dislocation of the Left Elbow

Associated Injuries to Rule Out

The "Terrible Triad" = elbow dislocation + radial head fracture + coronoid fracture. This creates an unstable joint requiring emergent orthopedic consultation. - Tintinalli's, p. 3421

Urgent Neurovascular Assessment

• Ulnar nerve - most commonly injured (up to 20% of cases): test little finger sensation and grip strength
• Median nerve - check thumb opposition, palmar sensation
• Brachial artery - radial pulse; absent pulse before reduction is associated with arterial injury in 5-13% of dislocations

Management

1. IV analgesia / procedural sedation (required - significant force needed for reduction)
2. Closed reduction - two main techniques:
   • Prone hanging method: Patient prone, elbow over bed edge, thumbs on olecranon, apply pressure superiorly + longitudinal traction on humerus
   • Supine traction-countertraction: Assistant stabilizes humerus; operator applies in-line traction on wrist/forearm, slightly flexes elbow, corrects medial/lateral displacement, then flexes to reduce
   • Successful reduction signified by a definitive "clunk"
3. Post-reduction X-ray to confirm reduction and re-assess for fractures
4. Neurovascular re-check after reduction
5. Above-elbow backslab in 90° flexion, followed by early mobilization at 1-2 weeks
6. If pulse does not return after reduction → emergent vascular surgery referral

Disclaimer: This is an AI-assisted radiological interpretation for educational reference. All clinical decisions must be confirmed by a qualified radiologist and/or orthopedic/emergency surgeon who can examine the patient directly.

You're Right to Question - Let Me Correct My Initial Diagnosis

Why Lateral Condyle Fracture - Not Elbow Dislocation

1. The radius and ulna maintain their normal articulation with each other - they are NOT completely displaced behind the humerus as in a true posterior dislocation
2. There is a fracture fragment at the lateral condyle of the distal humerus visible on the AP view
3. The elbow is positioned in flexion (not dislocated) - this mimics a dislocation appearance on the lateral view
4. The distal fragment is displaced posteriorly and inferiorly with pull from the extensor muscles attached to it
5. Open growth plates confirm this is a pediatric patient - lateral condyle fracture is the second most common pediatric elbow fracture after supracondylar fracture

Lateral Condyle Fracture - Key Facts

Radiographic Features (This Film)

• AP view: Widening of the intercondylar distance; a lateral bony fragment separated from the distal humerus
• Lateral view: Posterior/inferior displacement of the lateral condyle fragment
• The fracture line extends through the lateral physis (Salter-Harris type IV pattern)
• The status of the lateral trochlear ridge is the key diagnostic point - if incorporated into the distal fragment, the injury is unstable. - Rosen's Emergency Medicine, p. 3305

Management

Why This Fracture Is Clinically Important

• Nonunion (most feared - due to intra-articular synovial fluid bathing the fragment)
• Avascular necrosis of the lateral condyle
• Cubitus valgus deformity (leading to delayed ulnar nerve palsy years later - "tardy ulnar nerve palsy")
• Fishtail deformity of the distal humerus

Disclaimer: This is an AI-assisted interpretation. A qualified radiologist and orthopedic surgeon must evaluate the patient and imaging directly for definitive diagnosis and management.