Trend of convergent screw placement in variable angle proximal humerus plates

Abstract

Variable angle locking plates were developed to allow flexible screw trajectories and broader fixation within the humeral head in proximal humerus fractures, where fixation failure remains a common challenge. Whether this theoretical advantage is utilized in clinical practice remains unclear. Methods: This retrospective radiographic study evaluated 43 patients treated with locking plate fixation for proximal humerus fractures between 2015 and 2023. Eighteen patients received variable angle plates and 25 fixed angle plates. Screw trajectories were assessed on early postoperative radiographs and intraoperative fluoroscopy. Vertical screw distribution was measured as the percentage of anatomical neck coverage in the coronal plane, and axial screw spread was defined as the angle between the 2 most divergent screws on lateral fluoroscopic images. Results: Screws placed through variable angle plates covered a smaller proportion of the anatomical neck compared with fixed angle constructs. In the axial plane, fixed angle plates demonstrated a mean screw divergence of 40°, whereas variable angle plates showed significantly narrower spread, with a mean divergence of 15.4° (P