Neer’s terminology of four-segment classification of displaced fractures and fracture-dislocations relates pattern of displacement (two-part, three-part, or four-part) and key segment displaced. In each two-part pattern, segment named is one displaced. Two-part surgical neck fractures are impacted (A), unimpacted (B), and comminuted (C). All three-part patterns have displacement of shaft segment, and displaced tuberosity identifies type of three-part fracture. In four-part pattern, all segments are displaced. Fracture-dislocations are identified by anterior or posterior position of articular segment. Large articular surface defects require separate recognition.