Optimization Cervical Plates Using Finite Elemental AnalysisSarah Batchelor

ENGR 4350 Finite Elemental Analysis, Instructor: Sanjiv Sinha, Ph.D.

Methods: Autocad was used to draw the plate, bone and screws using the product specifications and bone detail from the most current studies. Once imported into Algor, the image was defined as a 3D brick and a mesh user-defined size of 0.575mm was placed over the entire image. The screws, the bone at the screw interface, and the bottom of the bone were assumed fixed. The bottom of the bone was assumed fixed to account for ligature and muscular interactions. Pressure loads of 60 kg/cm2 were placed around the bone, mimicking the maximum normal pressure loads and loading of 1962N was placed on the interior of the cervical plate around the screws, mimicking the pressure loads being transmitted from the bone, into the screw, and therefore into the bone.

Results: Common surgical grade implant materials titanium, PEEK, and cobalt-chromium were analyzed using FEA. Titanium had the largest deformations, and plastics are renown for failing over long term use. Cobalt-chromium gave the best results with maximum deformations of 0.35mm, stresses of 9058N/mm2, and reaction forces 281N observed in the bone.

Introduction: Thousands of unfortunate individuals suffer from neck pain associated with spinal discs. In order to alleviate this pain, the disc must be removed and then replaced, either by bone graft or a polymer implant. Removing the disc requires that the spine itself be stabilized. Due to the intensity of such surgeries, it is imperative that the implant be designed to allow minimum deflections in the bone, as allowed by the implant material. This project seeks to analyze and optimize a current cervical spine implant design, the Amendia Diamond.

Results: The results from the Cobalt-Chromium test show that the material is best suited for this specific implant. The deformations, stresses, and reaction forces fall well within the acceptable range for bone, and do not exceed maximum force capabilities of bone. The analysis could be improved by plate design that mimics bone curvature and actual 3D cervical bone rendering, which was unavailable at the time of analysis.

Conclusion: FEA studies are commonly used in the biomedical industry to map the implant bone interface. This study re-emphasizes the importance of that study: though all materials were surgical grade, the best material was fond to be Cobalt-Chromium, a conclusion reached only by FEA analysis. From an educational perspective, FEA aided in the understanding of the bone implant interaction and how it can act as fixed and transmit forces.