Predictive Value of DeltoidTuberosity Index in PlateOsteosynthesis of ProximalFractures: Is it Better than Age?

Introduction: Proximal humerus fractures (PHF) are considered fragility fractures, with increasing incidence in the elderly. Several risk factors negatively influence osteosynthesis outcomes, including age, bone density and medial hinge comminution. Age ≥65 is often considered a decision threshold in treatment algorithms. The deltoid tuberosity index (DTI) is a simple, reproducible method to evaluate local bone density. This study aimed to assess whether DTI is a better predictor than age for complications and re-interventions in PHF treated with locking plates. Methods: This retrospective study included 40 patients with PHF treated with open reduction and internal fixation with locking plates between 2021 and 2024. DTI was measured on pre-operative AP Grasey views by two independent shoulder specialists. Calcar screw-calcar distance and calcar reduction were also evaluated. Early complications (<12 weeks), late complications (>12 weeks), and the type of re-intervention were recorded. Results: Early complications occurred in 15% (n = 6), late complications in 27.5% (n = 11), and re-intervention was required in 25% (n = 10). DTI had good accuracy for predicting complications (AUC = 0.809), with an optimal cut-off of ≤1.64 (100% sensitivity, 92% specificity; Youden Index = 0.92). DTI was significantly lower in patients with late complications (1.34 vs 1.46; p = 0.001) and re-intervention (1.31 vs 1.45; p = 0.002), but not with early complications (p = 0.309). Age was not associated with early (p = 0.668), late complications (p = 0.148), or re-intervention (p = 0.889). There was no correlation between age and DTI (r = 0.232; p = 0.150). Calcar screw-calcar distance was significantly higher in early complications (11.23 vs 7.84 mm; p = 0.018) and re-intervention (10.77 vs 7.92 mm; p = 0.036). Calcar deviation had no significant associations. Conclusion: DTI is a valuable tool in the management of PHF, predicting complications and re-intervention more reliably than patient age.