Stryker 3D Printing for Artificial Joints; From R&D to Production

Stryker 3D Printing for Artificial Joints; From R&D to Production


[intro music]>>Robert Cohen: R&D engineers embraced us
right away. The idea that you could have a new process that could take designs and geometries
in totally different ways, it really allowed us to think very, very different. In fact,
it was the process that we were waiting for and looking for.>>Narrator: In the early 2000s, Stryker engineers
started exploring the potential of 3D printing for manufacturing cementless artificial joints.
For cementless models, manufacturers must develop porous interfaces, where implants
attach to bone. This promotes the ingrowth of bone tissue, what�s called “biological
fixation.” Stryker thought the technology might prove especially valuable for a tibial
baseplate — where the implant meets the upper shinbone in a total knee replacement. The
engineers thought 3D printing might produce optimal porosity, while also offering unprecedented
design freedom. But 3D printing with metals was still an emerging technology — far from
production-ready for artificial joints.>>Lewis Mullen: Obviously we’re making medical
devices so we have to make sure every aspect of those devices is looked at and make sure
we’re supplying the highest quality components. So it took a long time for us to make the
final leap into Additive. It wasn’t until 2013 that we released our first additive manufacturing
product. And within that time, it was about gathering data. It was about building up business
case as well as showing that the technology had the potential and was production capable.>>Narrator: At many points, Stryker engineers
had to develop their own know-how. Early on, especially, few industry-wide technical standards
were available.>>Robert Cohen: You’re actually creating
your standards and you have to create the performance standards for the product. That
we’re pretty good at. But consistency and looking at all the unknowns of additive manufacturing.
For instance, when you have a build plate and you’re making 10 different parts in one
run, are all the parts based on location of the build plate exactly the same? What is
the difference? If you look at different powder, powder configurations, lot by lot by lot of
material powder, were we creating the same part? When you made parts, did you have some
areas where maybe the consolidation of the powder wasn’t as great as you want and you
had some porosity?>>Narrator: Evaluation also involved conventional
testing for strength and durability.>>Lewis Mullen: In terms of the testing we
performed in during the development phase, if we take a tibial baseplate for example,
that tibial baseplate is loaded mechanically. When it’s implanted into the body it sits
within the knee and there’s forces that go through that, so we have to look and analyze
every single aspect of the mechanical loading that will go through joint’s lifetime. We
perform fatigue tests. We perform static material tests and then we also look at, you know,
how that will perform over long term.>>Narrator: Then came the challenges of scaling
up for manufacturing.>>Robert Cohen: Even after we had the design
validated and we had a part that passed fatigue testing, had dimensional integrity, that still
doesn’t mean you can make 1,000 of them.>>Narrator: As the R&D engineers performed
test after test, colleagues in supply chain and production began to embrace the Additive
Manufacturing challenge.>>Naomi Murray: It’s always difficult to
go from a bench top R&D process into a manufacturing process, but that’s what we do, that’s part
of the job. And yes, there were a lot of difficulties and things to get over, such as making sure
you have stable equipment. Making sure you understand the environment you need to be
manufacturing in. Making sure you understand what you need to be testing when you test
the component. Making sure you understand what the actual form, fit, and function of
the component is. But they were challenges we expected.>>Robert Cohen: So an example of one problem
is, let’s take that total knee tibia component that caps a bone resected tibia. In that case,
was every component flat when it came out of additive manufacturing? And at times, for
reasons we didn’t fully understand, we didn’t get the flatness that we wanted.>>Narrator: Testing led Stryker to understand
variables that could affect that flatness. And company engineers also addressed challenges
of quality assurance.>>Robert Cohen: One of the benefits of additive
manufacturing, it allowed us to make complex shapes. Well, complex shapes are actually
harder to measure and our quality assurance people now had to convert to laser inspection
and using lasers and looking at computer coordinate measuring machines in ways like never before.
That’s actually a good problem to have. That was okay. But for the mechanical integrity,
the porosity of the equipment, we could do chemical analysis on a part, make sure we
didn’t introduce light elements, hydrogen, oxygen, nitrogen. But by the same token, the
consistency and consolidation of a powder, deep within the solid construct, you couldn’t
see it. So what we decided to do was use micro CT. Just like one of our patients would go
for a CT scan in a hospital to look at a cross-section of their bone and see the health of their
bone, we do the same thing.>>Narrator: Stryker, and other companies
using additive manufacturing, say other techniques, like in-process monitoring, may prove effective,
too.>>Lewis Mullen: So, a lot of the machines
you see nowadays, you can take images of the build as it’s being performed and you can
potentially start to use some of those images as verification methods at the end of a build
to make sure that everything within that build has worked and is successful. So there is
potential with Additive because you have the flexibility and you are actually manufacturing
that material layer by layer to be able to perform this analysis and hopefully at some
point in the future be able to implement that as a verification as to the process at the
end.>>Narrator: Stryker had the engineering talent
and research dollars to embark on a very careful, and ultimately successful, journey with Additive
Manufacturing.>>Lewis Mullen: We’re proud of the tibial
baseplate because it was our first product that we had on the market from an Additive
Manufacturing perspective. It was a great achievement for everyone that was involved
in Additive, to have that finally released onto the market. We were able to input features
onto our tibial baseplate that we would not have been able to do with any other manufacturing
technologies. We can put solids in places where we wouldn’t have been able to with other
technologies. Our porous material could overlap with solid material, so design freedom was
a major benefit with the Additive Manufacturing technology.>>Narrator: But how might Stryker’s experience
help other companies at earlier stages in analyzing the business and technical merits
of Additive Manufacturing? We asked Stryker engineers about lessons they could share.>>Robert Cohen: I think companies that want
to go additive and decide to go additive and only decide to go additive at the front end
before doing their diligence on the work, are indeed making a mistake. I can tell you,
we are not taking all our components at Stryker and converting it to additive manufacturing.
There are some configurations that are quicker and easier and our conventional machining
and manufacturing is just fine for it.>>Narrator: But when Additive Manufacturing
may be an appropriate technology, Stryker says many resources are now available to help
companies make good decisions.>>Robert Cohen: I’ve often get asked, often
asked, especially by small companies, that we don’t have the resources that Stryker has.
How do we become successful in additive manufacturing and bring that into our product line? And
I could tell, the very first thing I say, “It’s fortunate you’re asking the question
today.” Additive’s maturity has come so far. To look at a part and to have a company that
sells the equipment or some consulting engineering house that may be familiar with additive manufacturing.
They could give you a good probability of success of that part. They could project cost
of that part and they can help you along the way with mechanical properties. People have
done software for additive manufacturing, simulation of additive manufacturing, you
could do so much predictive modeling even before you spend any money. Partnering with
material suppliers, partnering with the equipment manufacturers and even going to some of the
universities which have programs and professors that actually could do some of the analytics.
I think we’re living in a day and age right now that is not only extraordinary but the
help that’s out there for additive manufacturing is really quite phenomenal.

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