Towards the Feasibility Analysis and Additive Manufacturing of a Novel Flexible Pedicle Screw for Spinal Fixation Procedures

TL;DR

This study investigates a novel flexible pedicle screw designed for spinal fixation in osteoporotic patients, demonstrating its manufacturability via additive manufacturing and validating its bending capabilities through simulation and experiments.

Contribution

We introduce a new flexible pedicle screw design, simulate its morphability with FEA, and successfully manufacture it using DMLS, addressing limitations of traditional rigid screws.

Findings

FEA results agree with experimental bending tests

Additive manufacturing of FPS is feasible with DMLS

The novel FPS can bypass osteoporotic regions safely

Abstract

In this paper, we explore the feasibility of developing a novel flexible pedicle screw (FPS) for enhanced spinal fixation of osteoporotic vertebrae. Vital for spinal fracture treatment, pedicle screws have been around since the early 20th century and have undergone multiple iterations to enhance internal spinal fixation. However, spinal fixation treatments tend to be problematic for osteoporotic patients due to multiple inopportune variables. The inherent rigid nature of the pedicle screw, along with the forced linear trajectory of the screw path, frequently leads to the placement of these screws in highly osteoporotic regions of the bone. This results in eventual screw slippage and causing neurological and respiratory problems for the patient. To address this problem, we focus on developing a novel FPS that is structurally capable of safely bending to fit curved trajectories drilled by a steerable drilling robot and bypass highly osteoporotic regions of the vertebral body. Afterwards, we simulate its morphability capabilities using finite element analysis (FEA). We then additively manufacture the FPS using stainless steel (SS) 316L alloy through direct metal laser sintering (DMLS). Finally, the fabricated FPS is experimentally evaluated for its bending performance and compared with the FEA results for verification. Results demonstrate the feasibility of additive manufacturing of FPS using DMLS approach and agreement of the developed FEA with the experiments.