Finite-Element-Guided Design of Metallic and Bioresorbable Bone Screws: Linking Thread Geometry, Material Stiffness, and ACL Screw Mechanics

Abstract Bone screw fixation is governed by the thread geometry, material stiffness, contact friction, and loading path. Here, a staged finite-element workflow was used to screen bone-screw designs for bone-to-bone and ACL fixation. Two-dimensional models rapidly compared thread form, pitch, and material under axial loading and pullout displacement, while three-dimensional models evaluated diameter-pitch interactions, metallic material effects, pullout response, stress partitioning, and insertion torque. The 2D results showed radial stress attenuation and a trade-off in which V-shaped threads improved pullout but increased local stress. In 3D, screw diameter dominated the peak stress, and SS 316 and Ti6Al4 V behaved similarly within the metallic design space. Within the present modeling constraints, fine-pitch/metric threads emerged as candidate ACL designs when immediate pullout resistance is prioritized, whereas coarser buttress or square profiles appear more appropriate when reducing bone/graft stress is critical. Polymeric/composite screws should be paired with lower-stress thread profiles and validated experimentally because their lower stiffness may increase deformation risk.