Novel Technical Factors Affecting Proximal Humerus Fixation Stability.

Abstract

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. A retrospective radiological study. Level 1 trauma center. Clinical and radiological data from consecutive PHF patients treated between January 2007 and December 2013 were reviewed. Open reduction and internal fixation with the Synthes Philos locking plate. Postoperative radiographs were assessed for quality of initial reduction, humeral head offset, screw length, number and position, restoration of medial calcar support or the presence of calcar screws, and intra-articular screw perforations. Using SliceOMatic software, we validated a method to accurately identify screws of 45 mm or longer on AP radiographs. Follow-up radiographs were reviewed for complications. Among 110 patients included [mean age 60 years, 78 women (71%), 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). The importance of reduction and calcar support in PHF fixation is critical. This study highlights some technical factors to which the surgeon must pay attention: avoid varus reduction, maximize medial support, avoid screws longer than 45 mm in the proximal rows, and restore the humeral offset within 6 mm or less. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.