Designing an Anatomical Plate to Improve Biomechanics and Stability for Distal Humerus Fractures: FEM Investigation and the Influence of Meshing Strategy.

Abstract

Objectives: Distal humerus fractures require stable fixation to restore elbow function, yet conventional plates often exhibit a geometric mismatch with bone morphology, potentially compromising biomechanical performance. Our finite element analysis (FEA) compared a novel anatomical plate designed to conform to native humeral geometry with a conventional plate for treating type B1 distal humerus fractures. The influence of meshing strategy on the outcomes was also evaluated. Both adaptive and uniform approaches were considered.

Methods: A CT-based three-dimensional humerus model with heterogeneous bone properties was reconstructed from scans of a 37-year-old woman. An anatomically contoured plate was compared with a conventional locking plate. Adaptive and uniform meshing were applied separately to each model, and each construct was subsequently tested under 100 N tensile and compressive loads.

Results: The anatomical plate showed higher stiffness (up to 13%), a broader contact pressure distribution (23--28 MPa vs. conventional: 12--18 MPa), and a larger area of sticking contact, whereas the conventional plate produced higher shear stresses (p=0.113). Uniform meshing generated significantly greater interfragmentary motion than adaptive meshing (p=0.008) but caused unrealistically high screw stresses (up to 1526 MPa). Adaptive meshing predicted higher bone stresses, whereas uniform meshing concentrated stresses in the screws. Although meshing affected the absolute stress and strain magnitudes, the comparative differences between plate designs remained consistent.

Conclusion: The anatomically contoured plate offers greater biomechanical stability than conventional designs for distal humerus fractures, as evidenced by reduced displacement and maintained fragment positioning conducive to healing. An adaptive meshing strategy appears more suitable for FEA of complex fixation components because it yields more reliable stress distributions without altering the primary comparative conclusions. Further experimental validation is warranted before clinical application.