Andy Barter

This coral-like form is a spinal implant. Created by Californian medical company NuVasive, it is made from titanium and fits precisely between two vertebrae. By mimicking the porousness and stiffness of human bone, it can accelerate bone growth following back surgery.

Spinal surgeons typically use implants made from high-performance plastic, because the material is less rigid than metal, yet also porous. But NuVasive’s research demonstrated that, with the right design, titanium could be moulded closer to the form and stiffness of human bone – with the added benefit of being stronger than plastic. But how to make it as porous while keeping this strength? Put a computer in control of the design.


The process is known as generative design: NuVasive sets constraints – such as the implant’s weight and porousness – into its software, and then asks the algorithm to spit out solutions that fit the brief. Humans have preconceived notions about the way something needs to look, but computers don’t – so it’s easier for them to offer original ideas.

“You describe your problem, and the computer creates a large set of potential solutions,” says Jeff Kowalski, chief technology officer at Autodesk, which designed the Dreamcatcher programme used to create the implant. “In the time it would have taken you to do one design, Dreamcatcher has done all of them.”

Read next This CIA spy game reveals the secrets of successful teams This CIA spy game reveals the secrets of successful teams

Once the most suitable model has been selected by a human designer, NuVasive 3D prints the implant. The computer’s latticed, asymmetric design means it can be made of titanium, a material that is strong and easy to detect in X-rays, yet still lightweight. “We’re able to tell it what load we’re putting on the implant and then the lattice is actually able to grow and shrink in thickness based on those loads, which leaves us with the least amount of material to meet strength requirements,” says NuVasive development engineer Jesse Unger.

At present, the implant only comes in one size. But, as the 3D printing process becomes more efficient, each patient could get their own tailor-made implant that specifically matches the needs of their body and bone density. NuVasive’s director of product development, Jeremy Malik, says this will help overcome one of the big hurdles of spinal implant surgery: guaranteeing fusion between bone and implant, which can mean repeat surgeries if it doesn’t occur. “You can design the implant to load-share in a way that the bone has, theoretically, a better opportunity to grow – and potentially at a faster rate,” he says.

Generative design is being applied across industries. Tyre manufacturer Michelin is developing concept treads that can be 3D printed on demand to meet any road condition, be it dry, wet, or icy; architecture firm Herzog de Meuron used the process to optimise the acoustic spaces for music performances at the Elbphilharmonie in Hamburg. But these projects tend to be expensive one-offs. The promised land of generative design is products and devices created specially for each individual.

After all, at present, as 3D-printing pioneer Francis Bitonti explains: “You never get something that’s a perfect fit for your behaviour, you always get something that matches maybe 80 per cent of the public’s behaviour. What we can do now is have flexible designs.”


Bitonti’s New York studio uses generative design to create complex, geometric fashion items, but one of his first commissions was a scoliosis brace. Thanks to generative design, it could be tailored to the nuances of the patient’s spine, while also containing 75 per cent less material than conventional alternatives. “You can’t scale these braces as they are, because you go to an orthotist who has what’s like a wood shop – it’s medieval,” says Bitonti. “Now there’s the ability to bring about that idea of mass customisation.”

Bitonti imagines that eventually consumers will be given the option of buying subscriptions to brands – a design version of software as a service. Subscribe to a sportswear label that learns your athletic behaviour, and when you come to replace your training shoes, the next version is customised to suit or enhance your running style.

For human designers, this means change: once creators, they will have to become curators, using algorithms to come up with customised solutions for design problems. “It’s going to shift from this idea of the producer of ambiguity to somebody who’s building systems and algorithms that are responsive and adaptive,” Bitonti says. “That’s the goal of generative design.”