[Fractures of the humeral head. Conservative and surgical differential therapy].

The Neer classification for fractures of the proximal humerus is a system based on accurate identification of the four major fragments and their relationship to each other. There is a specific type of displaced 4-fragment fracture of the proximal humerus which consists in valgus impaction of the head fragment. This type of fracture is combined with a lower rate of avascular necrosis than that of other displaced 4-fragment fractures. In addition, the outcome is different according to whether a displaced 4-fragment fracture affects the surgical or the anatomical neck. Those through the surgical neck have a much lower rate of avascular necrosis than those through the anatomical neck. Therefore, 4-fragment valgus impacted fractures through the surgical neck should be treated by open reduction and internal fixation rather than by primary hemiarthroplasty in younger patients.