Establishing the appropriate position of proximal humerus locking plates: a cadaveric study of five plating systems and their anatomic reference measurements.

Background: The present study aimed to determine anatomic references for the placement of five proximal humerus locking plates.

Methods: Five proximal humerus locking-plate systems were placed on six human shoulder cadavers. Plates were positioned by fluoroscopic confirmation so that the inferior oblique screw was within 5 mm of the inferomedial cortex. Plate position was measured using the superior border of the pectoralis major tendon (PMT) to the bottom of the first slotted or nonlocking hole and top of the plate to the top of the greater tuberosity. The distance from the PMT insertion to the top of the humeral head was measured as a control.

Results: There was consistency within each plating system for both the distance from the PMT insertion to the first hole and the top of the plate to the greater tuberosity: Synthes first-generation [mean (SD) 13.7 mm (3.1 mm); 10 mm (1.3) mm], Synthes second-generation [28.2 mm (2.2 mm); 18.5 mm (2.7 mm)], Biomet OptiLock® [25.5 mm (2.7 mm); 18.7 mm (2 mm)], Stryker AxSOS® [5 mm (2.8 mm); 12.3 mm (3.3 mm)] and Acumed Polarus® [9.5 mm (1.8 mm); 14.8 mm (1.6 mm)].

Conclusions: The present study provides measurements that improve the accuracy of plate positioning for five plating systems.