Novel Technical Factors Affecting Proximal Humerus Fixation
Intra-articular screw cut-out is a common complication after proximal humerus fracture (PHF) fixation using a locking plate. This study investigates novel technical factors associated with mechanical failures and complications in PHF fixation.

Clinical and radiological data from consecutive PHF patients were reviewed.

Quality of initial reduction, humeral head offset, screw length, number, and location, restoration of medial calcar support or the presence of calcar screws, and intra-articular screw perforations were all evaluated on postoperative radiographs. Researchers validated a system for reliably identifying screws of 45 mm or longer on AP radiographs using SliceOMatic tools. Complications were verified on follow-up radiographs.

--Among 110 patients included [mean age 60 years, 78 women, follow-up 2.5 years] and the following factors were associated with a worse outcome. (1) Screws >45 mm in proximal rows [Odds Ratio (OR) = 5.3 for screw cut-out); (2) lateral translation of the humeral diaphysis over 6 mm (OR = 2.7 for loss of reduction); (3) lack in medial support by bone contact (OR = 4.9 for screw cut-out); (4) varus reduction increased the risk of complications (OR = 4.3).

Finally, in PHF fixation, the value of reduction and calcar help cannot be overstated. Avoid varus reduction, optimize medial support, avoid screws longer than 45 mm in the proximal rows, and restore the humeral offset within 6 mm or less are some of the technical factors highlighted in this report.