Position of polyaxial versus monoaxial screws in locked plating for proximal humeral fractures: analysis of a prospective randomized study

124 patients who suffered a proximal humeral fracture with displacement >1 cm and angulation of fragments > 45 degrees, were randomly assigned to treatment with either monoaxial or polyaxial screw-inserted locking plate fixation. The primary purpose of this study was to compare the chosen positioning of locking screws between the two treatment groups. Results demonstrated that there was no significant difference between the placement or positioning of polyaxial versus monoaxial screws. A mean of 6 screws purchased the humeral head in the monoaxial group compared to a mean of 4 in the polyaxial group. However, loss of fixation was observed more frequently when fixation (with either device) did not include at least one screw within the superoposterior region of the humeral head.