Laser-sintered prototypes of open hooks that attach to vertebral bodies/ribs. Utilized for evaluation, these are produced from 17-4 SS (stainless steel) material by DePuy Spine with Direct Metal Laser Sintering (DMLS) technology from EOS. (Image courtesy of DePuy Spine)
Prototyping and production accelerate with EOS’s laser-sintering tech
Laser-sintered prototypes of open hooks that attach to vertebral bodies/ribs. Utilized for evaluation, these are produced from 17-4 SS (stainless steel) material by DePuy Spine with Direct Metal Laser Sintering (DMLS) technology from EOS. (Image courtesy of DePuy Spine)
Surgery on the human spine is one of the most exacting, delicate procedures in the operating room. While the skill of the doctor is of paramount importance to a good outcome, the precision and reliability of the instruments they use are also critical.
As minimally invasive surgery (MIS) becomes one of the fastest-growing areas in spine treatment, orthopedic surgeons are demanding increasingly sophisticated tools. These must be sized for greater access and control through smaller incisions, made strong enough to cut through cartilage and bone, and built from materials that are biocompatible.
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Direct Metal Laser Sintering Reduces Development Lead Time
Getting the right instruments to a surgeon—and coming up with new or customized models as techniques advance and materials evolve—can be an arduous process. Prototyping, revisions, materials selection, cadaver testing and manufacturing can create total wait times of many months. DePuy Spine of Raynham, MA, is cutting lead times by employing laser-sintering technology from rapid manufacturer EOS.
DePuy Spine has worked and partnered with leading clinicians and researchers for over 20 years to advance knowledge of both professionals and patients in addressing spinal pathologies and to develop products to treat spine disorders.
Prototype Plate Bender, used to contour plates for spinal surgery, built by DePuy with the EOS M270 laser sintering system. (Image courtesy of DePuy Spine)
DePuy makes over 70 brand-name products with various product codes that are distributed globally from hubs in the US, UK and Switzerland. Using a single EOSINT M 270 direct metal laser sintering (DMLS) machine from EOS in their own shop, DePuy processed 2,000 prototype parts—benders, extractors, surgical screws, clamps, reduction devices and others—in the first year of use alone.
According to Staff Team Leader Peter Ostiguy, delivery times for surgical tool prototypes have shrunk from several months to less than a week in some cases.
“Laser sintering is very well-suited to our environment because of all the things we need to produce quickly,” he says.
“We’ve really impressed our surgeons with our ability to turn around what they’re looking for in a short amount of time.”
Surgeons Guide Prototyping Process
Surgeons’ opinions are important: some of them are active consultants to DePuy throughout the product development process.
“We work with the thought-leaders in the industry, many of whom tour our rapid prototyping lab every year as do other surgeons not on the project teams,” says Ostiguy.
Prototype of an Expedium SFX Cross Connector measuring device, which measures the distance between rods to indicate the size implant to use. Surgeons try out prototypes of DePuy Spine instruments in cadavers and give feedback on functionality and recommendations for improvements. (Image courtesy of DePuy Spine)
“What has cut development time so dramatically lately is the capability of the M 270 to build multiple iterations of a tool prototype in a matter of days.”
The DePuy development team starts with a basic design idea, often making a plastic prototype first (on a different machine in their shop), and shows it to the surgeons for feedback. After modifying the design according to the doctors’ input, DePuy may turn to the M 270 if the application is appropriate for creating a metal prototype.
From CAD Data To Prototype
The DMLS process begins with a CAD file of the product design, which defines each thin layer of a horizontal cross-sectioned model that is generated onto the work platform inside the machine. A first layer of 17-4 stainless-steel powder is deposited at a thickness of 20µm onto the work platform and then sintered by a focused laser beam.
The work platform is lowered and the process is repeated additively, layer by layer, until a three-dimensional metal part is produced (maximum dimensional limits are 10” x 10” x 8-1/2” high). In this manner extremely complex geometries are created automatically, directly from CAD data in just a few hours.
Giving Surgeons More Choice
“What’s nice about this machine is that we can easily make multiple iterations of a tool to give our doctors more choice,” says Ostiguy.
“In many instances we used to have to go with just one iteration, but now we have greater flexibility to present more options. There’s just no substitute for actually holding an item in hand.”
The consulting doctors can be very exacting about their requirements for tools such as blades, racks, tweezers, and calipers.
“When they review the prototypes they may ask for different handle angles, or different spring strengths,” says Ostiguy.
“It’s very easy to adjust the CAD design and make another iteration. Laser sintering lets us make virtually anything they ask for.”
A Paradigm Shift In Tool Design
The result of introducing laser sintering into DePuy’s Development Center has been a paradigm shift in the thought process for designing tools.
“We’re not designing for manufacturability any more, we’re designing for functionality. As designers, we were constantly thinking about how we were going to make something within process limits. With this machine, it really doesn’t matter,” Ostiguy says.
When the consulting doctors are satisfied with an instrument design, DePuy makes a final metal prototype with the M270 and sets up a cadaver section so the surgeons can put the item through its paces.
Cadaver testing of metal prototypes is the last stage in product development before DePuy sends the 3D model file for the approved piece to an outside vendor for manufacturing.
The finished items undergo a final round of mechanical testing and verification before being used in actual surgeries.
Biocompatible Materials Are Next
EOSINT M270 direct metal laster sintering (DMLS) machine. De Puy Spine processed 2,000 prototype parts of surgical equipment and devices on this type of machine in the first year of use alone. (Image courtesy of EOS)
Unlike prototypes tested in cadavers, instruments for in vivo surgical use must be made from materials that are biocompatible with the human body. Due to their success with DMLS for prototyping, DePuy recently purchased another M 270.
“If we can make instruments on our own machine we can save time and money and be responsive to our doctors’ requirements,” says Ostiguy.
The second M 270 machine will be dedicated to a single, heat-treatable material, EOS Stainless Steel PH1 (precipitation hardening stainless steel), which is characterized by high hardness, strength and corrosion resistance. PH1 can be machined, spark-eroded, welded, micro shot-peened, polished and coated if required.
The new M 270 is programmable to run layers of either 20 or 40 microns (a thicker layer cuts down on run time, a thinner one provides finer detail) and can process multiple materials as well.
Although his group is concentrating on the PH1 material for now, Ostiguy says, “the possibilities are endless for future product development with laser sintering.”
For more information visit www.depuyspine.com