How 3D printing and surgical robotics enable Stryker’s cementless knee implants

It’s been more than 10 years since Stryker launched its Triathlon Cementless knee implant, including the Triathlon Tritanium Baseplate and its 3D-printed surface.

Stryker designed that 3D-printed surface to encourage the patient’s bone to grow into the baseplate, securing the joint without cement. With cementless knees, surgeons and patients don’t have to worry about the potential weakening or loosening of cement over time, which could mean a patient has to go back in for another operation.

“We’re seeing an increasing adoption rate, where 50% of our overall knees are put in cementless,” Stryker Knee GM and VP Lisa Kloes said in an interview. “When we first came out with it, [people thought] we were crazy to not put cement in because that was the gold standard. We were the first to market, and now we have over a million cementless knees implanted a decade in. It’s just great to see the success.”

She said American Joint Replacement Registry data show a statistically significant increase in survivorship with the Triathlon Cementless baseplate compared to all cemented and cementless implants.

Kloes joined the world’s largest orthopedic device developer 19 years ago and moved to its knee business in 2022. In a conversation with Medical Design & Outsourcing, she discussed how Stryker uses additive manufacturing and surgical robotics to innovate with ortho products like the titanium Triathalon Cementless knee.

“It definitely took some courage to make that leap to create this product, and 3D printing was still relatively new in med device at that point,” she said.

Today, Stryker’s manufacturing facility in Cork, Ireland, has 94,000 ft² dedicated to 3D printers.

“We are one of the largest 3D manufacturing companies in med device or otherwise,” Kloes said. “… It started with basically the Tritanium Tibial Baseplate. We now have over 10 business units within Stryker that are doing 3D-printed products.”

The following conversation has been edited for space and clarity.

How does additive manufacturing enable better ortho implants?

Kloes: “The 3D printing aspect is really about the design element and the architecture that it creates. It’s basically mimicking cancellous bone and promotes that bony ingrowth versus a flat surface that you put cement on.”

How does Stryker use laser sintering and titanium powder to create that unique design?

Kloes: “The base plate itself is a solid structure. And then we print on layer upon layer of the next design elements that create almost like a webbing, like cancellous bone. The other products are created with a foundry where you put it in a mold, and then it comes out as one piece. You can’t create the intricacy of the webbing without 3D printing. And it’s layer upon layer, 50 microns thick of each layer.”

How has 3D printing accelerated product development?

Kloes: “It has expedited our new product development process significantly, because we’ll take user need inputs from our surgeon consultants — the problem we’re trying to solve for and potential designs that meet that need — and we can get them back in a lab and give them two or three designs to try it in a lab setting. Then let’s tweak this, tweak that, they go to the hotel, come back in the lab the next day, and they have the new design. The engineers are literally right there with them, tweaking the design of their computers while they’re in the lab setting. Before [we could do this,] they would go home, they’d come back three months later — whenever we can get their time to come back to our lab — and we have to create new CAD drawings and then send it to forging and make the product. It’s just lightyears ahead of what we can do and how quick we can iterate design and get it in their hands, which is the most important thing to get feedback.”

Do you have an example of how 3D printing has shortened those cycles?

Kloes: “Right before coming to joint replacement, I was with trauma. We were working on what’s called the Pangea plating portfolio. … It just got 510(k) clearance. That was the first project I’ve been involved with that used this rapid prototyping. The number of SKUs — the screws, the plates — typically would have taken us at least five years from beginning to end. And we got 510(k) clearance in half the time, two-and-a-half years. And it’s a great product. I don’t think that we sacrificed anything for that reduction in time because of the way we were able to iterate and get the new designs in front of our consultants.”

Related: How Stryker is using 3D printing to advance orthopedics

How does surgical robotics fit in with cementless?

Kloes: “[With robotics], we are looking at the specific anatomy of the patient and aligning the implants to their anatomy, versus some jigs that put them in the same no matter what the patient presents with. So robotics really does go hand in hand with the cementless design, and we have a higher rate of adoption for our customers that use robotics with cementless.”

Accurate bone cutting is even more important with cementless knees, so can you explain how a robotic system like Mako helps?

Kloes: “We have what’s called AccuStop, a haptic [technology that helps the surgeon cut]. So we plan the case based upon a CT scan of the patient, and then in the procedure, we map the anatomy to the computer so the computer knows where the patient is in space, and then the robotic [arm] executes — with the assistance of the surgeon — that cut. It is highly precise. You don’t have any flaws in the cut. Some surgeons will say that because of the accuracy of the cuts, the fit is even better, and it increases the success of the cementless bony ingrowth.”

Have you had the opportunity to meet with patients after they’ve had a knee replaced, and what was that like?

Kloes: “It’s humbling, because of the impact you’re making on people’s lives. What we hear both on the knee side and the hip side is, ‘I wish I would have done it sooner.’ … You see people really compromising what they love to do. It really is important to make that connection because we know what we’re doing every day is important, but when you bring a patient — at least once a year we bring in a surgeon, their patient, and somebody from the team — to talk about their experience like, ‘What was your life before you had knee pain? What was it like after? What was the procedure like? What was the recovery like? And what are you able to do now?’ That’s with our engineers, our manufacturing teams, just so everybody that’s involved with bringing it to market and keeping it on the market know the impact that they’re making. And it’s pretty remarkable to be a part of it.”

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This story was originally published on OCt. 25, 2023, and updated on Oct. 26 with edits to quotes for clarity and additional information from Kloes.