Fig. 6A–B.

Graphs show the ROM in the directions considered likely to be at risk for dislocation. (A) Neck diameter and neck angle, but not head size, have an effect on ROM in the direction of maximum risk for anterior dislocation. (B) Neck diameter and neck angle also affect the ROM in the direction of maximum risk for posterior dislocation. However, reducing the neck angle has the opposite effect on posterior dislocation. HD = head diameter; ND = neck diameter, NA = neck angle.