ABSTRACT
BACKGROUND: Varus collapse is a common failure mode of proximal humerus fracture (PHF) fixation. The purpose of this study was to analyze predictors of varus collapse of PHF after open reduction, internal fixation (ORIF). METHODS: All patients who underwent ORIF of a PHF from January 2008 to July 2018 were identified. Known predictors of fixation failure were assessed, including calcar distance, calcar ratio, and calcar restoration. Additionally, the presence of cross-threaded screws was determined. The primary outcome analyzed was varus collapse of the fracture defined as a change in neck shaft angulation to less than 120°. RESULTS: There were 112 patients identified who underwent ORIF of a PHF that met inclusion criteria. The population was 75.0% female (84/112), average age was 62.5 ± 10.4 years (range 40.0-87.9), and average body mass index was 28.0 ± 5.5 (17.5-46.4). There were 17 with varus collapse. In 11 of the 17 patients (64.7%), there was screw cross-threading (vs. 31/95 [32.6%] in those that did not collapse); P = .012. In addition, 8 of the 17 (47.1%) did not have restoration of the calcar (vs. 16/95 [16.8%]; P = .005). CONCLUSION: This study identifies 2 surgeon-controlled variables that can contribute to varus collapse after ORIF of PHFs. Cross-threading of locking screws and failure to restore the medial calcar can be a function of implant design, surgeon technical skill, and/or bone quality.
