A 55-year-old sustains a proximal humerus fracture. Neer classification divides the proximal humerus into four segments. Which part must be displaced >1 cm or angulated >45° to be counted as a 'part'?
- A Humeral head only
- B Greater and lesser tuberosities only, not the shaft
- C Greater tuberosity, lesser tuberosity, humeral head, and shaft — any segment displaced >1 cm or angulated >45° ✓
- D Humeral head and surgical neck only
Correct answer: C. Greater tuberosity, lesser tuberosity, humeral head, and shaft — any segment displaced >1 cm or angulated >45°
Explanation
In the Neer classification, the four segments are the humeral head (anatomical neck), greater tuberosity, lesser tuberosity, and humeral shaft (surgical neck). A segment is 'counted' only when it is displaced more than 1 cm or angulated more than 45° relative to its neighbours. A 1-part fracture means no segment meets displacement criteria regardless of fracture line number; 4-part fractures have the highest risk of avascular necrosis of the humeral head due to disruption of the arcuate artery.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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