A Finite Element Analysis of a Biodegradable Cervical Plate and Screw System

Choi, Jaeyon; Che, Lihua; Kim, Keung Nyun; Yi, Seong; Ha, Yoon; Yoon, Do Heum; Shin, Dong Ah

doi:2017.3.1.12

Asian J Pain > Volume 3;2017 > Article

Clinical Article

Asian Journal of Pain 2017;3(1):12-16.
DOI: https://doi.org/10.35353/ajp.3.1.12 Published online May 30, 2017.

A Finite Element Analysis of a Biodegradable Cervical Plate and Screw System

Jaeyon Choi, Lihua Che, Keung Nyun Kim, Seong Yi, Yoon Ha, Do Heum Yoon, Dong Ah Shin

Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea

Correspondence: Dong Ah Shin, Tel: +82-2-2228-2174, Fax: +82-2-393-9979,
Email: cistern@yuhs.ac

Abstract

Objective
To evaluate a biodegradable cervical plate and screw system by 3D modeling and finite element analysis.
Methods
The authors are developing a biodegradable cervical plate and screw system using poly-L-lactic acid (PLLA). A computational model was evaluated before experimenting it into humans. The system was fabricated using 3D modeling and analyzed with finite element analysis using a commercially available software (Abaqus 6.4, Simulia, USA). Compression and bending tests were performed by applying a force of 100 N to the screw to analyze the applied von Mises stress. The screw and plate were combined, and a force of 100 N was applied to the screw to analyze the von Mises stress on the screw and plate.
Results
When a bending force of 100 N was applied to the distal 1/3 part of the screw, widening of the head and anchor of the screw, bending of approximately 20°, and concentration of von Mises stress at the pin were observed. These phenomena indicate the possibility of head and anchor fractures when severe loading is applied. When a compressive force of 100 N was applied to the screw in the plate and screw combined model, concentration of von Mises stress at the blocking parts of the plate. The phenomenon indicate the possibility of plate fracture when severe loading is applied.
Conclusion
Because biodegradable material is weak, biomechanical weakness may result in breakage of a system. According to our research, two parts of screw should be combine into one and the plate design also be modified without weak points.

Key Words: Biodegradable materials; Spinal implant; Finite element analysis; Biomechanics; Anterior cervical discectomy and fusion