Fig. 1.

The binary system (LEGO system) developed by Hertel et al. [19] represents the four parts of the proximal humerus (head, greater tuberosity, lesser tuberosity, shaft) using the LEGO blocks. The absence of a bond between any of the four parts locates the fracture plane. A number is then assigned to each fracture pattern (Reprinted with permission from Hertel R, Hempfing A, Stiehler M, Leunig M (2004). Predictors of humeral head ischemia after intracapsular fracture of the proximal humerus. J Shoulder Elbow Surg.; 13: 427–33. doi:10.1016/j.jse.2004.01.034)