Biomechanical advantages of the proximal femoral bionic nail with triangular support structure in the treatment of intertrochanteric fractures: a coronal fracture heatmap modeling and finite element comparison of three implant designs

Coronal fracture fragments (CFs) are highly prevalent in intertrochanteric fractures and represent a significant risk factor for internal fixation failure. This study combined anatomical and engineering approaches to construct the first coronal fracture heatmap model and evaluate the biomechanical advantages of the Proximal Femoral Bionic Nail (PFBN) compared to conventional implants in managing intertrochanteric fractures with coronal plane involvement. A retrospective analysis was conducted on 623 patients with intertrochanteric fractures. CT data were used to reconstruct three-dimensional models, and a Python-based algorithm generated coronal fracture heatmaps. Three finite element models representing high‑incidence CFs patterns (GT, GT/LT, and GT/LPC) were developed for PFBN, Proximal Femoral Nail Anti-rotation (PFNA), and Dynamic Hip Screw with Derotational Screw (DHS + DS). Von Mises stress (VMS), displacement, contact pressure, and tangential micromotion were analyzed under simulated physiological loading of 2100 N. CFs were identified in 96.3% of intertrochanteric fractures. Single CFs predominated in younger patients (50.0%), while multiple CFs were more common in elderly patients (62.0%, p < 0.05). PFBN demonstrated the lowest implant VMS across all fracture models, with an overall VMS reduction ranging from 12.92% to 40.46% compared with conventional implants. PFBN also showed significant differences in femoral stress distribution, and it significantly reduced contact pressure (by up to 34.6%) and tangential micromotion (by up to 34.9%), suggesting a potential biomechanical advantage. CFs are highly prevalent in intertrochanteric fractures, especially multiple fragments in elderly patients. Under the assumptions and loading conditions of this finite element study, PFBN showed lower computed implant stress, displacement, and tangential micromotion than PFNA and DHS + DS across the three modeled coronal-fragment patterns. These computational findings suggest a potential biomechanical advantage of the triangular support structure.