Clinical validation of the DRoPH score: a preoperative tool for estimating reduction difficulty in proximal humerus...

Proximal humerus fractures are common injuries that are frequently associated with considerable technical challenges during surgical reduction and fixation. Although anatomical reduction is crucial for fracture healing and functional recovery, the anticipated difficulty of achieving satisfactory reduction is difficult to estimate preoperatively. The Difficulty of Reduction of Proximal Humerus Fractures (DRoPH) score was recently developed through a structured expert consensus process to estimate anticipated reduction difficulty based on predefined fracture- and patient-related characteristics. The aim of this study was to perform an initial clinical validation of the score.

We retrospectively analyzed patients who underwent plate fixation of proximal humerus fractures at a tertiary trauma center between January 2014 and December 2024. DRoPH scores (0-10 points) were stratified into low (0-3), moderate (4-6), and high (7-10) difficulty categories. Validation was based on operative duration, postoperative reduction quality according to the criteria described by Schnetzke et al., and postoperative complications. Multivariable regression analyses were performed to assess the independent association of the DRoPH score with the primary outcomes after adjustment for age, sex, and surgical approach. Inter- and intra-rater reliability were assessed using intraclass correlation coefficients (ICC).

Of 1,012 patients treated for proximal humerus fractures, 392 met the inclusion criteria and had complete datasets available for analysis. Of these, 151 (38.5%) were classified as low, 186 (47.4%) as moderate, and 55 (14.0%) as high difficulty according to the DRoPH score. Operative duration increased significantly with increasing DRoPH scores, with an adjusted increase of 7.3 min per score point (95% CI 5.7-9.0; p < 0.001). Reduction quality deteriorated across difficulty categories, and higher DRoPH scores were independently associated with malreduction (OR 1.30 per point, 95% CI 1.12-1.50; p = 0.001). Overall complication rates increased from 15.2% in low-difficulty fractures to 34.5% in high-difficulty fractures, and the DRoPH score remained independently associated with complications in multivariable analysis (OR 1.15 per point, 95% CI 1.03-1.28; p = 0.012). Inter- and intra-rater reliability of the overall DRoPH score were excellent (ICC 0.96 and 0.95, respectively).

This study provides initial clinical validation of the DRoPH score as a reliable and clinically applicable tool for estimating reduction difficulty in proximal humerus fracture fixation. Higher DRoPH scores are independently associated with longer operative duration, increased risk of malreduction, and higher complication rates. The score may therefore serve as a useful adjunct for preoperative planning and risk stratification in surgically treated proximal humerus fractures. Further multicenter validation studies are warranted.

Level III, retrospective cohort study.