ASTM F2624: Standard Test Method for Static, Dynamic, and Wear Assessment of Extra-Discal Single Level Spinal Constructs was the guideline used for this project. Our design would need to accomodate for compression, torsion, flexion, extension, and lateral bending motion profiles .To further understand the needs of this project, interviews were conducted with engineers at SeaSpine, and precedents in implant testing were found. Through research, we found comparative designs and materials that would be used in our final product.

Image source: https://www.seaspine.com/products/spinous-process-system/

A variety of potential designs were sketched, explored, and evaluated for future functionality. Once 2D drawings were determined, 3D models were made using Fusion360. CAD was used to determine geometry, dimensions, and interface between parts. Finite element analysis was also used to determine structural integrity of the design.

An Ender 3 and an Ender 3 Pro were used to 3D print prototype parts for test fitting on SeaSpine's testing fixtures. Evaluations of the fit and functionality were made with these prototypes in order for improvements to be made to the testing fixtures. A cycle of prototyping and testing was undergone until parts were determined to be perfectly compatible with SeaSpine's testing system as well as ASTM F2624.

Utilizing what was learned from the 3D printed prototypes, final CAD parts and assemblies were made for all testing fixture setups. Assemblies were created for a compression/torsion system, a flexion/extension system, and a lateral bending/shear system. All systems were designed to interface with a circular isolation chamber which could be fitted around the full testing setup.

Once final CAD and dimensions were determined, parts were then converted into Geometric Dimensioning and Tolerancing (GD&T) compliant drawings for manufacturing. Using a SolidProfessor course on GD&T as well as feedback from Zac Dooley, the team was able to create accurate and acceptable drawings to send to manufacturing. All drawings were created using the 2018 ASME Y14.5 Dimensioning and Tolerancing standard.

Three sources were used for manufacturing final parts. SeaSpine's in-house machine shop, UCSD's Campus Machine Shop, and PartsBadger. For local manufacturers, material was supplied through McMaster-Carr. GD&T drawings and .STEP files of CAD were sent to the different sources for manufacturing tools.

Once all manufactured parts were attained, we tested them on SeaSpine's testing setups. Fit and function were evaluated and minor adjustments were made. Some changes included larger stabilizing rods to reduce play in the systems and larger spinous process plates to increase implant grip.

Once all testing setups were determined as functional, they were given to SeaSpine for use in future testing projects.