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RAPID PROTOTYPING Prototyping complex human anatomy

Sep 28, 2020

Auxein Medical, a next-generation creator of advanced orthopaedic implants and other medical devices, was facing challenges in custom tooling prototype models for its patients as it was an expensive and tedious process. The company was seeking options that would tackle all the challenges and understand the intricacies of human anatomy. That is when it reached out Stratasys, a 3D Printing company with FDM, PolyJet and Stereolithography systems, which set industry standards and helped customers in their pursuit of innovation. The case study provides insights on how the Stratasys F170 3D printer solved all the problems Auxien Medical was seeking solutions for.

Large scale production of patient-specific models faces an obvious conundrum – if every human is unique, how can bespoke devices be produced en masse and within reasonable timeframes? Auxein Medical, a next-generation creator of advanced orthopaedic implants and other medical devices, has tackled this challenge head-on; “No matter what, every individual deserves personal and high-quality care,” remarked Gaurav Luthra, Technical Director, Auxien Medical. The company provides patient-specific implants and anatomy prototypes to its global customer base, enabling surgeons, medical practitioners and researchers to plan for and execute complex operations on patients of all shapes and sizes. Behind Auxein’s personalised prototypes of today – and the speed and accuracy with which they can deliver – sits a Stratasys F170.

The issues with conventional methods

Historically, producing a model of a patient’s femur, for example, would require tooling prepared via conventional manufacturing methods. If preparing a bespoke femur prototype for each of John, Jane and Jim would require custom tooling, it would be too costly and lengthy as a business model. Thus, the only option for a manufacturer would be to create anatomy prototypes based on average body geometries, subdivide them into a handful of sizes and mass-produce under a ‘few-sizes-fit-all’ philosophy to address large slices of the populace. The issues with such conventional methods are self-evident.

For one, broad average body geometries fundamentally ignore the nuances between individuals. Mapping out a plan to diagnose and address a patient issue would be inherently imprecise; practitioners would be forced to rely on prior experience to visualise patient anatomy, for example. Once in operation, surgeons would need to react to patient idiosyncrasies in real-time and would not have the ‘perfect fit’implant needed to reduce the risk to an absolute minimum. Second, preparing tooling via traditional methods presents a variety of practical challenges; it requires metal and plastic cutting, which is cost-prohibitive, takes anywhere from days to weeks (especially if there are revisions that need to be made) and often simply cannot accommodate the highly complex shapes and details of the human anatomy.

Introducing the Stratasys F170

Auxein Medical needed a new functional testing and concept modelling tool to tackle these various challenges – one that would recognise the nuances of individual human anatomy, allow for quick fixes and revisions, compress overall timelines and save cost. In early 2019, a Stratasys partner, Altem Technologies, visited Auxein Medical to understand and diagnose the previous process issues. Altem Technologies’ representative demoed the Stratasys F170 3D printer. The F170 is capable of producing parts within an accuracy of +/- 0.200 mm. This means complex patient-specific anatomy and implant models can be printed with true-to-life precision. As Luthra mentioned, “It is extremely critical that the fit of the patient-specific implant is perfect and easy on the human anatomy. With the printing capability of 0.127 mm layer thickness using Stratasys F170, the accuracy and fitment parameters are easily achievable.”

Auxein Medical uses ABS, with its high strength combined with infill parameter settings, enables them to easily perform functional testing by producing durable 3D printed parts and fixing atop metal implants. As Mohit Kumar, Senior Research Engineer, Auxein Medical, remarked, “We can easily perform functional testing on the 3D printed models because of the exceptional mechanical properties of ABS. Plus, producing customised medical models with complex shapes are easily executable due to the availability of water-soluble hands-free support material.”

Design validation revolutionised

The introduction of Stratasys 3D Printing capabilities to Auxein Medical’s workflow has transformed design validation and the ultimate end-to-end manufacturing process. Now, Auxein Medical records an individual patient’s anatomy through CT and MRI scans rendering the scan(s) through CAD and can rapidly print a physical model of this patient data and/or a CMF/Maxillofacial implant model. With simple post-processing like sanding and branding, Auxein Medical can speedily present ultra-precise prototypes for engineers and surgeons to review and modify. If a patient prototype or implant model requires correction, it can be done quickly and efficiently.

Through the adoption of Additive Manufacturing, Auxein’s previous design validation timeframe of 10+ days has been cut down to just two days. Plus, without the need for expensive conventional tooling and retooling, Auxein Medical estimates the average cost per custom model has been cut by 80%. Through cost and time savings, the Stratasys F170 has catalysed meaningful business expansion, enabling Auxein to extend its portfolio to include power tools casing for joint and trauma surgery and other medical devices. Auxein Medical sees integrity, quality and innovation as the backbone of growth in its enterprise and is looking forward to continued investment in 3D Printing and similar technologies to further this philosophy.

Courtesy: Stratasys

Image Gallery

  • Patient fractured bone prototype with fitted Metal Implant (TRAUMA: Wise-Lock Plate)

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