Session: 05-15-03: General Topics in Biomedical and Biotechnology - III

Paper Number: 96227

96227 - Effect of Fixations on Biomechanical Performance of Additively Manufactured Cranial Implants 

Using additive manufacturing (AM) or 3D printing for patient-specific customized implant design is becoming the new norm as an alternative to traditional manufacturing. AM coupled with solid models of the skull allows the freedom of designing complex geometries while yielding the required form and improved functionality. This new technology enables the potential to construct cranial implants with desired mechanical and biological characteristics that ensure the optimized design with the least stress and deformation. An ideal customized cranial implant should be patient-specific, have zero gap between the implant and the skull, optimum number of fixations, few stress concentrations, and minimum deflection due to external loading. Additionally, it should have a material gradation mimicking the vicinal bone to ensure minimal stress shielding. Additively manufactured cranial implants are still new, bringing in the question of reliability and sustainability of implant construction. The long-term biomechanical performance is affected by the implant material, anticipated loads on the implant assembly, implant-skull interface geometry and, constraints caused by the addition of new structure to the skull. The overall effectiveness of the cranial implants depends on the interplay between all these factors. Fixation plays a vital role in the success of implantation. The relationship between fixation and the biomechanical behavior of implants needs to be evaluated.

The role of fixation in the biomechanical response of implants was investigated using finite element analysis by considering implant shapes, sizes, materials, numbers of fixation points, and their relative positions. Mechanical characterization of the implants was conducted to find the optimum number of fixation locations required to minimize deformation and stress. Three different geometric shapes (circular, elliptical and square shaped) were considered as implants in this study. It was found that the optimum number of fixations points should be between 4 to 5 based on the defect size and shape. Also, the optimum curvilinear distance between two screws should be below 40 mm further indicating that more than 3 fixations are required to keep deformation under external load minimum. Another important observation is that when the fixations are shifted inwards towards the diagonal, the curvilinear distance between two screws would decrease for the same number of fixation screws. In essence, the curvilinear distance is not only dependent on the number of fixations but also on the location of the screws from the outer periphery. Additionally, the symmetric orientation of screws (when possible), resulted in reduced deflection. The findings from this research can assist in providing a better guideline on the fixation of cranial implants during surgical decision-making.

Presenting Author: Fariha Haque The Ohio State University

Presenting Author Biography: Fariha Haque is a Ph.D Student in the Department of Mechanical and Aerospace Engineering at The Ohio State University.

Authors:

Fariha Haque The Ohio State University
Anthony F Luscher The Ohio State University
Kerry-Ann Mitchell The Ohio State University Wexner Medical Center
Alok Sutradhar The Ohio State University