Democratizing the Design of Custom Medical Devices

As personalized healthcare continues to reshape the medical sector, rapid progress is being made in the field of custom-made devices. Orthopedic and dental implants, orthoses and prosthetics are among an ever-increasing number of products being tailored to individual patients' unique needs. These custom-made medical devices often dramatically improve outcomes and can also shrink the cost of treatment. The technologies enabling this healthcare revolution include 3D imaging - which can rapidly measure a patient's internal physiology - and additive manufacturing, which can efficiently produce devices either on a one-off basis or in very low volumes.

Advanced design and optimization software is the third part of the equation. This software gives medical professionals the tools necessary to develop solutions either partially or completely shaped around a patient's unique requirements. Not surprisingly, it's a demanding field. For example, implicit modeling is well-suited to handling the complex geometries (including stochastic lattices) that typically go into medical devices. However, to date, implicit modeling tools have proved too expensive, too complex, and too distinct (in terms of look, feel, and user experience) than conventional design software.

To realize the full potential of custom-made devices, designers need tools that are both capable, efficient, and readily accessible to the widest range of users. Fortunately, the latest generation of software is combining the familiarity and usability of mainstream CAD tools with the tailored capabilities medical device designers need.

Welcome to a New Dimension of Medical Device Design

Sales of additively manufactured medical devices are skyrocketing. According to one estimate, the global market for these devices is worth $4.74 billion in 2024, and could rise to $12.77 billion by the end of the decade. Custom-made devices are the driving force behind this growth - and it's easy to see why. Nature is a remarkable design engineer, organically creating structures within the human body that are both strong and lightweight. Today's design and optimization software can help designers recreate these structures. However, the manufacturing techniques traditionally employed in engineering, such as casting and machining, impose considerable restrictions on final products' shape, size, and volume. For custom-made medical device designers, this limitation has long put the most potentially impactful designs out of reach.

But additive manufacturing has rewritten the rules. Designers can now manufacture their creations without having to make major compromises or commit to large production runs. Consequently, the combination of sophisticated design software and additive manufacturing is already being employed in a diverse array of custom and semi-custom medical devices.

Moreover, applications aren't limited to human patients. Veterinary surgeons are also making greater use of personalized orthopedic implants. In a similar vein, sports equipment designers are leveraging these technologies to create custom-made products for elite professionals and weekend warriors alike.

Harnessing the Power of the Lattice

As far as human orthopedic implants are concerned, one of the most interesting (and challenging) aspects of custom design work is the use of cellular materials, including regular and stochastic lattices. Lattices appear throughout the natural world, from beehives and coral reefs to dragonfly wings and plant stems. The cellular structure of bone also resembles a stochastic lattice, incorporating randomly arranged - rather than regular and repeating - cell patterns.

One key advantage of lattices is that they slash the quantity of material required for 3D printing. But material savings aren't the full story. For example, practitioners are utilizing lattices made from titanium to create orthopedic implants that foster natural bone growth. By harnessing the process of osseointegration, the aim is to connect the patient's living bone with the surface of the load-bearing implant.

Optimizing the speed and extent of osseointegration represents a major design challenge. There's now a considerable body of research showing that lattice type and pore size both have a significant impact on natural bone growth within a patient. That's why designers need software that embraces the widest possible range of lattice types and gives them the freedom to adjust an array of different parameters such as pore size, porosity, and beam/strut diameter. To achieve the closest possible match with patients' unique needs, designers are also looking for solutions that will enable them to manipulate and fine-tune the elements that comprise a stochastic lattice, such as struts and nodes.

A concept model for the acetabular cup of a hip implant generated using implicit modeling in Altair® Inspire™.

From Niche to Mainstream

To date, such capabilities have typically been the preserve of niche design and optimization software solutions. However, support for stochastic modeling and similar functionalities has historically tended to come at the expense of both cost and ease of use, meaning newcomers to the field of medical device design traditionally needed to invest considerable time and effort before becoming productive.

But today, a new generation of software is making it far easier and quicker for designers to work on sophisticated personalized and semi-personalized medical devices, including lattice-based implants. Altair® Inspire™, for instance, offers exceptional design flexibility by incorporating a wide variety of advanced geometry engines, including implicit modeling. Moreover, Inspire is built around an interface that's instantly recognizable to any CAD user. It includes drag-and-drop functionality, the high levels of automation necessary to speed complex processes such as implicit modeling, and the ability to fine-tune lattices' individual elements. Capabilities can be further extended with a Python API that enables users to create their own tools and automate the product by scripting repetitive workflows.

Using the stochastic lattice feature in Inspire with implicit modeling to mimic the bone structure within a human femur.

Unleashing Human Creativity

When selecting design software, device developers also need to consider the bigger picture. The design and optimization of lattices isn't an end in itself. Ultimately, designers are looking to develop a solution that can be successfully manufactured - correctly the first time - via additive manufacturing. That could involve the use of a range of solvers and tools. Here again, mainstream software solutions may offer the advantage of being part of a much wider design ecosystem. In the case of Inspire, that includes a flexible, units-based licensing model that provides seamless access to an integrated suite of tools. Designers only pay for the resources they need, when they need them.

Personalized medical devices are a natural evolution within healthcare. New technologies and advances in scientific understanding are helping people create treatments that reflect the simple truth that every human body is unique. But in many respects, we've barely scratched the surface of what's possible.

In research and education institutions around the world, pioneering work is underway that's pushing the boundaries of possibility. The convergence of additive manufacturing and sophisticated design and optimization software is providing the foundations for progress that will deliver better outcomes for more people. However, the critical ingredient is human creativity. That's why democratization is so important. By giving more designers the opportunity to apply their ideas quickly and efficiently, the latest wave of software will accelerate a revolution in custom-made medical devices that's just getting started. Over the past two decades, such software has transformed design and development throughout the engineering sector and beyond. Over the next few years, it's poised to do the same in healthcare.

To learn more about Altair's design and simulation solutions for medical applications, visit https://altair.com/healthcare. To learn more about Inspire, visit https://altair.com/inspire/.

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