Multifunctional Design of Triply Periodic Minimal Surface Structures for Temporary Pediatric Fixation Devices

Abstract

Fracture fixation and limb deformity correction in paediatric orthopaedics often use temporary metallic fixation devices. These devices’ higher stiffness compared to cortical bone leads to stress shielding, causing significant bone density reduction, periprosthetic loosening, and bone growth interference. 3D‐printed triply periodic minimal surface (TPMS) structures present a promising engineering solution to match bone stiffness while ensuring reliable implant strength. This study employs finite element modelling and experimental testing to identify optimal multi‐functional TPMS‐based lattices that meet the required design constraints of (1) stiffness in the range of cortical bone, (2) strength in the range of cortical bone, (3) minimum osteointegration to facilitate the implant removal after healing, and (4) manufacturability with limited defect sensitivity. Six different types of Ti‐6Al‐4V material TPMS structures manufactured via Laser Powder Bed Fusion were evaluated for their ability to target the lower and upper bounds of paediatric cortical bone stiffness. Lattices based on the Primitive unit cell design were superior, demonstrating the highest strength/stiffness ratio, best manufacturability, and potentially reduced osteointegration due to larger pore size, smaller surface area, and lowest negative Gaussian curvature compared to other investigated TPMS types.This article is protected by copyright. All rights reserved.