Mark Crawford, Contributing Writer03.16.21
Orthopedic device manufacturers are focused on designing high-quality products that comply with evolving national and international regulatory standards and meet the growing needs of an aging population. As life expectancy gets longer, people want to complete their daily activities comfortably in their old age, which creates a growing interest in medical procedures such as knee, hip, and spine surgeries.
“This trend is driving a need for mobility-preserving, minimally invasive procedures and therefore performance implantable components to treat injuries in this active cohort,” said Eoghan Groonell, senior marketing executive for Aran Biomedical, a Galway, Ireland-based provider of implantable device development and manufacturing services for the medical device industry. “This trend is particularly evident in the sports medicine market.”
OEMs increasingly seek advice from their designers and contract manufacturers (CMs) on developing products that will make them stand out from the competition. These devices are often complex yet must also be cost effective, which challenges engineers to improve their designs through the innovative use of automation and robotics, materials, advanced design software tools, or manufacturing and/or inspection equipment, such as additive manufacturing (AM).
To stand out OEMs usually must have an orthopedic product that significantly reduces overall procedure time and improves patient outcomes, both during and post-surgery, that is also easy and comfortable to use. This is especially true for minimally-invasive (MI) techniques or robotics that assist with the procedure. OEMs also want fast, innovative, and high-precision prototyping to test materials, dimensions, shapes, assembly, fit, and function, and validate processes, especially for making the submittal process to the FDA go smoothly.
For example, much of PHACON’s business is designing custom prototypes for its customers. “The conversation usually starts with the question, ‘Can you build this for me?’” said Brandon Gehrmann, account executive for the Atlanta, Ga.-based provider of anatomical models that mimic human specimens. “The answer is if they need it, we can build it.”
Gehrmann related PHACON was recently asked to build cortical and cancellous bone blocks for testing a drill clutch. “The OEM also wanted a different bone density based on their targeted demographic,” he said. “We had the ability to match this density so they could go ahead and conduct their testing for the FDA without delay.”
Latest Trends
One of the largest technology trends in the orthopedic space is the advancement of MI robotic- or computer-assisted surgeries. Numerous players are launching surgical robotics products and developing new concepts. These breakthroughs will ultimately reduce procedure time spent in the OR or ER, and improve outcomes for both surgeons and patients. More surgeons are using robotic arms because they improve performance during complex procedures—for example, lower leg alignment, soft tissue balance, and the sizing of components. Robotic arms also reduce surgeon fatigue and give them the option to remotely perform certain types of surgeries.
With COVID-19, companies are genuinely concerned about using human specimens and exposing their employees to potential infection. This safety concern has created a need for alternative methods of testing. With so many project managers working from home and limited access to office and lab space, there is “great need for haptic, detailed, and human-equivalent artificial materials,” said Gehrmann. “PHACON helps meet this need by providing bone material that is safe to use, without the need for expensive labs or human specimens.”
A company recently asked PHACON to design a leg for a fasciotomy procedure. The requirement was that it had to exceed the capabilities of what was available on the market, which the PHACON design team achieved with multiple fascia compartments. “We are now using this new technology to create shoulder and arm models for vascular procedures,” said Gehrmann. “This level of detail and realism, for example, allows someone to conduct a procedural seminar without having to deal with expensive tissue labs and banks and the disposable costs of human tissue.”
Interest continues to grow in textile scaffolds that mimic the natural tissues in the body and can stimulate osseointegration and cell growth. Flexible textile components create intriguing design options for implants and can be made from a variety of materials or combination of materials to create specific mechanical properties. For example, textile-based parts can be designed for static or dynamic loads to enhance tissue integration or for abrasion resistance.
“OEMs are moving toward implants with lower profiles and tuneable elongation properties, enabled through various textile technologies, including braiding and weaving,” said Groonell. “These configurations complement the availability of performance input biomaterials, high-tenacity synthetic fibers, and natural fibers.”
Textile constructs are inherently versatile in their design and performance. When coupled with high-performance biomaterials, they can significantly improve the effectiveness of many orthopedic repair procedures. For example, ultra-high-molecular-weight polyethylene (UHMWPE), commonly known by the brand name Dyneema, is one of the strongest and most durable input yarns available. It also enables lower-profile solutions, without the bulk that is often associated with other biomaterials. It also has an established clinical history and meets all ASTM and ISO standards.
Surgeons (and their healthcare systems) have a keen interest in performing MI surgeries. For these procedures, “more companies are requesting longer working lengths for the in-the-body portions of their devices, so the full procedure requires smaller surgery incisions and those incisions can be placed at the optimal locations,” stated Weston Fiebiger, product development engineer for Nordson MEDICAL, a Minneapolis, Minn., provider of solutions for hydration and delivery of allograft, autograft, or synthetic bone graft materials. “This in turn provides patients with less pain and a faster recovery with a smaller chance of infection.”
One company has gone beyond MI to incisionless by designing a needle arthroscope system that can complete surgical procedures through a needle, instead of an incision. Designed and developed by Arthrex, a Naples, Fla.-based global medical device company that specializes in product development, especially arthroscopic solutions. Called the NanoScope, the needle arthroscopy system is both diagnostic and therapeutic in that it provides a direct view into the surgery site and allows follow-up nanoscopic instrumentation if needed, making it a less-invasive procedure compared to regular arthroscopy, which improves the patient experience with fewer to no incisions, reduced pain and inflammation, and less risk of infection at the procedure site.1
What OEMs Want
When it comes to design, OEMs seek innovation, product differentiation, low cost, and speed to market. They expect fast turnaround times with the ability to quickly iterate on design concepts to reach design freeze, in the shortest possible time.
“Customers expect to pick up models/prints and be able to turn around a tray layout that flows with surgical technique within one to two weeks and full design with artwork within two weeks,” said David Hollner, manager for U.S. cases and trays for Intech, a Memphis, Tenn.-based global contract manufacturer of surgical instruments, implants, cases and trays, and silicone handles. “Production-equivalent prototypes are expected two weeks after design approval, so a four-to-six-week turnaround from the initial request.”
To further improve speed to market and reduce costs, trays are becoming increasingly modular to accommodate interchangeable layouts in the field. There is also increased emphasis on automated washing capabilities. “As a result, we have designed off-the-shelf ultra-high perforated trays that allow for quick response while ensuring perforation rates close to 70 percent,” added Hollner.
OEMs also want design help for making innovative products for highly specific markets, as well as redesigning legacy products to boost market share. Implants are historically a strong segment of the orthopedic market and OEMs are always looking for ways to improve implant function, osseointegration, and patient outcomes. For example, Hilton Head Island, S.C.-based startup OrthoDx has invented an implantable sensor that can detect micronic shifts in orthopedic implants that would indicate the onset of loosening of joint components.2
A constant pressure by OEMs on their supply chain partners is process certification. As products get smaller and more complex, with shorter timelines, OEMs expect more from their designers and CMs to meet quality demands and provide their own validations, sharing in the risk of the development process, especially with newer technologies such as additive manufacturing, which can require more steps to validate. This is one reason many products still require traditional machined prototypes as part of the verification and validation process.
“We machine and measure parts down to the millionths, with complex curves, bends, and shapes, and that level of precision can’t be reached with rapid prototypes,” said Philip Allen, vice president of sales and marketing for Lowell, a Minneapolis, Minn.-based contract manufacturer of complex implants and instruments for the orthopedic and cardiovascular markets. “Traditional machined prototypes allow us to verify that parts actually fit together as they should, and are used to meet inspection requirements. We also work with our customers to align inspection processes as part of verification, and traditional prototypes are invaluable for this work.”
Advanced Technologies Spur Innovation
Laser micromaching continues to evolve—and sometimes is the only way to cut features in complex devices. For example, the fastest, highest-precision laser in micromanufacturing today is the femtosecond laser, which can process nearly any type of solid material, including layered, mixed, laminated, or coated materials, with the highest quality and precision.
“Femtosecond lasers are transforming manufacturing by performing high-speed, high-precision material removal, additive processes such as laser-induced forward transfer, and sometimes even hybrid subtractive-additive processes when needed,” said Matt Nipper, director of engineering for Laser Light Technologies, a Hermann, Mo.-based provider of laser micromachining to the medical device, life sciences, and microelectronic industries. “Features as small as 0.0005 inches [13 microns] can be laser-cut with high dimensional accuracy.”
Designers prefer the ultrashort pulses of femtosecond lasers because there is no thermal damage or heat-affected zones to the material being processed, which is ideal for sensitive materials. Because the cuts are clean with no burrs, secondary processes are typically not required. Lasers are ideal for drilling high-precision holes and micro-texturing implant surfaces.
“Laser-cutting processes are being integrated more often with ‘conventional’ punching processes, allowing for greater personalization of containers, with system-specific branding and logos,” said Hollner.
Another creative application of lasers in designing orthopedic products is using them to texture metal surfaces to make them more antimicrobial. For example, it is well-known that copper is a naturally antimicrobial material; however, it takes hours to kill most bacteria on a copper surface. Purdue University researchers have developed a laser system that etches nanoscale grooves into the metal, increasing its surface area and enhancing its microbe-killing abilities, thereby reducing post-surgery infection rates.3 “This one-step laser-texturing technique effectively enhances the bacteria-killing properties of copper’s surface,” stated lead researcher and materials engineering professor Rahim Rahimi. “The process selectively generates micron and nanoscale patterns directly onto the targeted surface, without altering the bulk of the copper material.”
For increasingly complex products with intricate designs and tight tolerances, manufacturers are relying more on design for manufacturing (DFM) to identify the best and most cost-effective manufacturing process.
Using DFM during the prototyping stage is the best way to identify and work out any design flaws before the production process gets locked in. Finite element analysis (FEA) is a crucial DFM tool that predicts how a proposed medical device will respond to real-world forces such as vibration, load, heat, fluid flow, electrostatics, and other physical effects. FEA will reveal a product’s design weaknesses and the most probable points of failure, which can then be fixed through redesign.
“FEA advancements provide a deeper look into mechanical properties and how the component will respond to forces, without going through the whole design process,” said Fiebiger. “This provides clarity and eases some stresses if we believe a requirement might not be able to be met.”
Compared to DFM, DFI—design for inspection—is often overlooked. The total cost of manufacturing a product always includes some cost associated with inspection. DFI evaluates how a component will be inspected and how the drawing or model can be modified to make the inspection process as clear as possible.
Additive manufacturing (AM)/3D printing is fast-becoming an essential tool for prototyping and design. Easy accessibility to these processes gives device manufacturers the ability to design and build prototypes and devices that cannot be machined or built otherwise in a cost-effective manner—a capability that greatly expands engineering and design options. AM is used to print custom-made orthopedic implants using patient-specific measurements. Spinal interbody implants and acetabular cups have also become routine 3D-printed products. Recent advancements in AM methods have improved the regularity of internal pore structure patterns, creating complex, repeatable geometries that improve osseointegration.
“Additive manufacturing is becoming more accessible and efficient at an exponential rate,” said Fiebiger. “Build volumes are getting larger, material selection is getting wider, resolution is getting finer, and prices are dropping. With these advances, complex design and materials no longer need to be prototyped by an outside vendor. This allows in-house prototyping at a fraction of the time and cost, with little to no harm to the design.”
When rapid prototyping is facilitated by iterative design and AM processes, orthopedic device manufacturers can shorten the product development cycle and deliver their new products to market faster. However, implants that bear loads other than pure compression, such as hip stems, remain challenging because of strength issues. Even though AM capabilities are rapidly advancing, most orthopedic devices still require secondary machining after being 3D printed.
Better Materials, Better Designs
Orthopedic OEMs continue to support advances in research and design. Of particular interest are new materials with improved physical and chemical behaviors that can even be combined to provide highly specific mechanical or chemical properties. Finding the right material for a new device can impact its design, shape, functionality, durability, and long-term effectiveness.
Prototyping and design in the niche market of graft materials have been especially active. “We have been approached by many graft material companies that require simple solutions to hydration and delivery of their graft,” stated Fiebiger. “All grafts require different solutions, so depending on material and customer needs, we will provide a 3i [influence, importance, imagination] brainstorming event that will end with the design and delivery of a customized prototype.”
Graft material, depending on composition, can be expensive. Greater efficiencies in dispensing this material with little to no material loss is therefore essential for controlling costs. To meet this need, Nordson MEDICAL developed its OsteoPrecision delivery device to facilitate MI surgeries. For example, developing a cannula or tube that fits through a smaller incision greatly improves the efficiency of MI procedures. “With a normal syringe, the cannula’s inside volume would end up being dead volume that the physician could not use for the procedure and therefore be waste,” said Fiebiger. “We developed an integrated stylet that provides effective and easy dispensing of graft material with little to no material loss.”
Coatings continue to evolve, especially for antibacterial properties, which allow designers to make safer products. National University of Science and Technology MISIS scientists have created an antibacterial nano-coating for implants based on boron nitride, which is highly effective against microbial pathogens (up to 99.99 percent).4
Bone-like materials are also in high demand. Scientists at the University of Birmingham in the U.K. have invented a new thermoplastic biomaterial that could have broad applications for orthopedic design. Called “adaptable nylon,” this material could facilitate bone-replacement procedures or MI surgeries that require flexibility in implant materials.5 “This new class of biocompatible plastic is as strong as nylon, but much easier to shape and manipulate due to its unique structural design, which is only accessible using our synthetic approach,” said lead researcher Josh Worch. “We specifically addressed these challenges by creating a tough plastic with changeable mechanical properties [varying stiffness and/or stretchability], excellent processability, and shape-memory behavior. It is a really fascinating material that can mechanically compete with conventional hard plastics such as polycarbonates or acrylics, in addition to other nylons.”
Dimension Inx, a Chicago, Ill.-based developer of tissue-engineered regenerative medical products, has created a suite of new 3D-printable biomaterials called “3D Paints.”6 One of these, known as “hyperelastic bone,” is nearing FDA approval. Hyperelastic bone consists of 90 weight percent calcium phosphate ceramic microparticles, linked by a matrix of 10 weight percent high-quality, biodegradable polymer. “The composition and microstructure are so similar to natural bone that resulting computed tomography reconstructions of 3D-painted hyperelastic-bone parts are difficult to distinguish from natural bone,” said Adam Jakus, co-founder and chief technology officer.
A wide range of 3D-painted materials can be produced, including metals and alloys, ceramics, and biological powders made from decellularized tissues and organs. The company has created hundreds of materials with this process, using simple room-temperature 3D printing.
“Any machine that operates via material extrusion will work, including fused deposition modeling machines and liquid, gel, and paste extrusion machines, often referred to as direct ink write, robocasting, or bioprinting,” Jakus added.
Of special interest to designers is that all 3D paints are compatible with each other, meaning multi-material structures can be created. They can even be mixed prior to or during printing to create materials with blended or gradient functionality that change over length or depth—a property that is essential for tissue and organ fabrication.
Jakus plans to continue to develop more biomaterials and partner with other companies to design future devices.
“We look at it more as the innovation hub, where we work with these partners to develop new devices that are either based on our materials, or they have their own materials that they want to print using our process to generate new products in their portfolio,” said Ramille Shah, co-founder and chief scientific officer.7
“You’re no longer necessarily fixed to titanium and plastics,” Jakus added. “You could design entirely new materials. If you had an ideal material, what would it be? Dimension Inx is in a place now where we could probably design that material.”
References
Mark Crawford is a full-time freelance business and marketing/communications writer based in Madison, Wis. His clients range from startups to global manufacturing leaders. He also writes a variety of feature articles for regional and national publications and is the author of five books.
“This trend is driving a need for mobility-preserving, minimally invasive procedures and therefore performance implantable components to treat injuries in this active cohort,” said Eoghan Groonell, senior marketing executive for Aran Biomedical, a Galway, Ireland-based provider of implantable device development and manufacturing services for the medical device industry. “This trend is particularly evident in the sports medicine market.”
OEMs increasingly seek advice from their designers and contract manufacturers (CMs) on developing products that will make them stand out from the competition. These devices are often complex yet must also be cost effective, which challenges engineers to improve their designs through the innovative use of automation and robotics, materials, advanced design software tools, or manufacturing and/or inspection equipment, such as additive manufacturing (AM).
To stand out OEMs usually must have an orthopedic product that significantly reduces overall procedure time and improves patient outcomes, both during and post-surgery, that is also easy and comfortable to use. This is especially true for minimally-invasive (MI) techniques or robotics that assist with the procedure. OEMs also want fast, innovative, and high-precision prototyping to test materials, dimensions, shapes, assembly, fit, and function, and validate processes, especially for making the submittal process to the FDA go smoothly.
For example, much of PHACON’s business is designing custom prototypes for its customers. “The conversation usually starts with the question, ‘Can you build this for me?’” said Brandon Gehrmann, account executive for the Atlanta, Ga.-based provider of anatomical models that mimic human specimens. “The answer is if they need it, we can build it.”
Gehrmann related PHACON was recently asked to build cortical and cancellous bone blocks for testing a drill clutch. “The OEM also wanted a different bone density based on their targeted demographic,” he said. “We had the ability to match this density so they could go ahead and conduct their testing for the FDA without delay.”
Latest Trends
One of the largest technology trends in the orthopedic space is the advancement of MI robotic- or computer-assisted surgeries. Numerous players are launching surgical robotics products and developing new concepts. These breakthroughs will ultimately reduce procedure time spent in the OR or ER, and improve outcomes for both surgeons and patients. More surgeons are using robotic arms because they improve performance during complex procedures—for example, lower leg alignment, soft tissue balance, and the sizing of components. Robotic arms also reduce surgeon fatigue and give them the option to remotely perform certain types of surgeries.
With COVID-19, companies are genuinely concerned about using human specimens and exposing their employees to potential infection. This safety concern has created a need for alternative methods of testing. With so many project managers working from home and limited access to office and lab space, there is “great need for haptic, detailed, and human-equivalent artificial materials,” said Gehrmann. “PHACON helps meet this need by providing bone material that is safe to use, without the need for expensive labs or human specimens.”
A company recently asked PHACON to design a leg for a fasciotomy procedure. The requirement was that it had to exceed the capabilities of what was available on the market, which the PHACON design team achieved with multiple fascia compartments. “We are now using this new technology to create shoulder and arm models for vascular procedures,” said Gehrmann. “This level of detail and realism, for example, allows someone to conduct a procedural seminar without having to deal with expensive tissue labs and banks and the disposable costs of human tissue.”
Interest continues to grow in textile scaffolds that mimic the natural tissues in the body and can stimulate osseointegration and cell growth. Flexible textile components create intriguing design options for implants and can be made from a variety of materials or combination of materials to create specific mechanical properties. For example, textile-based parts can be designed for static or dynamic loads to enhance tissue integration or for abrasion resistance.
“OEMs are moving toward implants with lower profiles and tuneable elongation properties, enabled through various textile technologies, including braiding and weaving,” said Groonell. “These configurations complement the availability of performance input biomaterials, high-tenacity synthetic fibers, and natural fibers.”
Textile constructs are inherently versatile in their design and performance. When coupled with high-performance biomaterials, they can significantly improve the effectiveness of many orthopedic repair procedures. For example, ultra-high-molecular-weight polyethylene (UHMWPE), commonly known by the brand name Dyneema, is one of the strongest and most durable input yarns available. It also enables lower-profile solutions, without the bulk that is often associated with other biomaterials. It also has an established clinical history and meets all ASTM and ISO standards.
Surgeons (and their healthcare systems) have a keen interest in performing MI surgeries. For these procedures, “more companies are requesting longer working lengths for the in-the-body portions of their devices, so the full procedure requires smaller surgery incisions and those incisions can be placed at the optimal locations,” stated Weston Fiebiger, product development engineer for Nordson MEDICAL, a Minneapolis, Minn., provider of solutions for hydration and delivery of allograft, autograft, or synthetic bone graft materials. “This in turn provides patients with less pain and a faster recovery with a smaller chance of infection.”
One company has gone beyond MI to incisionless by designing a needle arthroscope system that can complete surgical procedures through a needle, instead of an incision. Designed and developed by Arthrex, a Naples, Fla.-based global medical device company that specializes in product development, especially arthroscopic solutions. Called the NanoScope, the needle arthroscopy system is both diagnostic and therapeutic in that it provides a direct view into the surgery site and allows follow-up nanoscopic instrumentation if needed, making it a less-invasive procedure compared to regular arthroscopy, which improves the patient experience with fewer to no incisions, reduced pain and inflammation, and less risk of infection at the procedure site.1
What OEMs Want
When it comes to design, OEMs seek innovation, product differentiation, low cost, and speed to market. They expect fast turnaround times with the ability to quickly iterate on design concepts to reach design freeze, in the shortest possible time.
“Customers expect to pick up models/prints and be able to turn around a tray layout that flows with surgical technique within one to two weeks and full design with artwork within two weeks,” said David Hollner, manager for U.S. cases and trays for Intech, a Memphis, Tenn.-based global contract manufacturer of surgical instruments, implants, cases and trays, and silicone handles. “Production-equivalent prototypes are expected two weeks after design approval, so a four-to-six-week turnaround from the initial request.”
To further improve speed to market and reduce costs, trays are becoming increasingly modular to accommodate interchangeable layouts in the field. There is also increased emphasis on automated washing capabilities. “As a result, we have designed off-the-shelf ultra-high perforated trays that allow for quick response while ensuring perforation rates close to 70 percent,” added Hollner.
OEMs also want design help for making innovative products for highly specific markets, as well as redesigning legacy products to boost market share. Implants are historically a strong segment of the orthopedic market and OEMs are always looking for ways to improve implant function, osseointegration, and patient outcomes. For example, Hilton Head Island, S.C.-based startup OrthoDx has invented an implantable sensor that can detect micronic shifts in orthopedic implants that would indicate the onset of loosening of joint components.2
A constant pressure by OEMs on their supply chain partners is process certification. As products get smaller and more complex, with shorter timelines, OEMs expect more from their designers and CMs to meet quality demands and provide their own validations, sharing in the risk of the development process, especially with newer technologies such as additive manufacturing, which can require more steps to validate. This is one reason many products still require traditional machined prototypes as part of the verification and validation process.
“We machine and measure parts down to the millionths, with complex curves, bends, and shapes, and that level of precision can’t be reached with rapid prototypes,” said Philip Allen, vice president of sales and marketing for Lowell, a Minneapolis, Minn.-based contract manufacturer of complex implants and instruments for the orthopedic and cardiovascular markets. “Traditional machined prototypes allow us to verify that parts actually fit together as they should, and are used to meet inspection requirements. We also work with our customers to align inspection processes as part of verification, and traditional prototypes are invaluable for this work.”
Advanced Technologies Spur Innovation
Laser micromaching continues to evolve—and sometimes is the only way to cut features in complex devices. For example, the fastest, highest-precision laser in micromanufacturing today is the femtosecond laser, which can process nearly any type of solid material, including layered, mixed, laminated, or coated materials, with the highest quality and precision.
“Femtosecond lasers are transforming manufacturing by performing high-speed, high-precision material removal, additive processes such as laser-induced forward transfer, and sometimes even hybrid subtractive-additive processes when needed,” said Matt Nipper, director of engineering for Laser Light Technologies, a Hermann, Mo.-based provider of laser micromachining to the medical device, life sciences, and microelectronic industries. “Features as small as 0.0005 inches [13 microns] can be laser-cut with high dimensional accuracy.”
Designers prefer the ultrashort pulses of femtosecond lasers because there is no thermal damage or heat-affected zones to the material being processed, which is ideal for sensitive materials. Because the cuts are clean with no burrs, secondary processes are typically not required. Lasers are ideal for drilling high-precision holes and micro-texturing implant surfaces.
“Laser-cutting processes are being integrated more often with ‘conventional’ punching processes, allowing for greater personalization of containers, with system-specific branding and logos,” said Hollner.
Another creative application of lasers in designing orthopedic products is using them to texture metal surfaces to make them more antimicrobial. For example, it is well-known that copper is a naturally antimicrobial material; however, it takes hours to kill most bacteria on a copper surface. Purdue University researchers have developed a laser system that etches nanoscale grooves into the metal, increasing its surface area and enhancing its microbe-killing abilities, thereby reducing post-surgery infection rates.3 “This one-step laser-texturing technique effectively enhances the bacteria-killing properties of copper’s surface,” stated lead researcher and materials engineering professor Rahim Rahimi. “The process selectively generates micron and nanoscale patterns directly onto the targeted surface, without altering the bulk of the copper material.”
For increasingly complex products with intricate designs and tight tolerances, manufacturers are relying more on design for manufacturing (DFM) to identify the best and most cost-effective manufacturing process.
Using DFM during the prototyping stage is the best way to identify and work out any design flaws before the production process gets locked in. Finite element analysis (FEA) is a crucial DFM tool that predicts how a proposed medical device will respond to real-world forces such as vibration, load, heat, fluid flow, electrostatics, and other physical effects. FEA will reveal a product’s design weaknesses and the most probable points of failure, which can then be fixed through redesign.
“FEA advancements provide a deeper look into mechanical properties and how the component will respond to forces, without going through the whole design process,” said Fiebiger. “This provides clarity and eases some stresses if we believe a requirement might not be able to be met.”
Compared to DFM, DFI—design for inspection—is often overlooked. The total cost of manufacturing a product always includes some cost associated with inspection. DFI evaluates how a component will be inspected and how the drawing or model can be modified to make the inspection process as clear as possible.
Additive manufacturing (AM)/3D printing is fast-becoming an essential tool for prototyping and design. Easy accessibility to these processes gives device manufacturers the ability to design and build prototypes and devices that cannot be machined or built otherwise in a cost-effective manner—a capability that greatly expands engineering and design options. AM is used to print custom-made orthopedic implants using patient-specific measurements. Spinal interbody implants and acetabular cups have also become routine 3D-printed products. Recent advancements in AM methods have improved the regularity of internal pore structure patterns, creating complex, repeatable geometries that improve osseointegration.
“Additive manufacturing is becoming more accessible and efficient at an exponential rate,” said Fiebiger. “Build volumes are getting larger, material selection is getting wider, resolution is getting finer, and prices are dropping. With these advances, complex design and materials no longer need to be prototyped by an outside vendor. This allows in-house prototyping at a fraction of the time and cost, with little to no harm to the design.”
When rapid prototyping is facilitated by iterative design and AM processes, orthopedic device manufacturers can shorten the product development cycle and deliver their new products to market faster. However, implants that bear loads other than pure compression, such as hip stems, remain challenging because of strength issues. Even though AM capabilities are rapidly advancing, most orthopedic devices still require secondary machining after being 3D printed.
Better Materials, Better Designs
Orthopedic OEMs continue to support advances in research and design. Of particular interest are new materials with improved physical and chemical behaviors that can even be combined to provide highly specific mechanical or chemical properties. Finding the right material for a new device can impact its design, shape, functionality, durability, and long-term effectiveness.
Prototyping and design in the niche market of graft materials have been especially active. “We have been approached by many graft material companies that require simple solutions to hydration and delivery of their graft,” stated Fiebiger. “All grafts require different solutions, so depending on material and customer needs, we will provide a 3i [influence, importance, imagination] brainstorming event that will end with the design and delivery of a customized prototype.”
Graft material, depending on composition, can be expensive. Greater efficiencies in dispensing this material with little to no material loss is therefore essential for controlling costs. To meet this need, Nordson MEDICAL developed its OsteoPrecision delivery device to facilitate MI surgeries. For example, developing a cannula or tube that fits through a smaller incision greatly improves the efficiency of MI procedures. “With a normal syringe, the cannula’s inside volume would end up being dead volume that the physician could not use for the procedure and therefore be waste,” said Fiebiger. “We developed an integrated stylet that provides effective and easy dispensing of graft material with little to no material loss.”
Coatings continue to evolve, especially for antibacterial properties, which allow designers to make safer products. National University of Science and Technology MISIS scientists have created an antibacterial nano-coating for implants based on boron nitride, which is highly effective against microbial pathogens (up to 99.99 percent).4
Bone-like materials are also in high demand. Scientists at the University of Birmingham in the U.K. have invented a new thermoplastic biomaterial that could have broad applications for orthopedic design. Called “adaptable nylon,” this material could facilitate bone-replacement procedures or MI surgeries that require flexibility in implant materials.5 “This new class of biocompatible plastic is as strong as nylon, but much easier to shape and manipulate due to its unique structural design, which is only accessible using our synthetic approach,” said lead researcher Josh Worch. “We specifically addressed these challenges by creating a tough plastic with changeable mechanical properties [varying stiffness and/or stretchability], excellent processability, and shape-memory behavior. It is a really fascinating material that can mechanically compete with conventional hard plastics such as polycarbonates or acrylics, in addition to other nylons.”
Dimension Inx, a Chicago, Ill.-based developer of tissue-engineered regenerative medical products, has created a suite of new 3D-printable biomaterials called “3D Paints.”6 One of these, known as “hyperelastic bone,” is nearing FDA approval. Hyperelastic bone consists of 90 weight percent calcium phosphate ceramic microparticles, linked by a matrix of 10 weight percent high-quality, biodegradable polymer. “The composition and microstructure are so similar to natural bone that resulting computed tomography reconstructions of 3D-painted hyperelastic-bone parts are difficult to distinguish from natural bone,” said Adam Jakus, co-founder and chief technology officer.
A wide range of 3D-painted materials can be produced, including metals and alloys, ceramics, and biological powders made from decellularized tissues and organs. The company has created hundreds of materials with this process, using simple room-temperature 3D printing.
“Any machine that operates via material extrusion will work, including fused deposition modeling machines and liquid, gel, and paste extrusion machines, often referred to as direct ink write, robocasting, or bioprinting,” Jakus added.
Of special interest to designers is that all 3D paints are compatible with each other, meaning multi-material structures can be created. They can even be mixed prior to or during printing to create materials with blended or gradient functionality that change over length or depth—a property that is essential for tissue and organ fabrication.
Jakus plans to continue to develop more biomaterials and partner with other companies to design future devices.
“We look at it more as the innovation hub, where we work with these partners to develop new devices that are either based on our materials, or they have their own materials that they want to print using our process to generate new products in their portfolio,” said Ramille Shah, co-founder and chief scientific officer.7
“You’re no longer necessarily fixed to titanium and plastics,” Jakus added. “You could design entirely new materials. If you had an ideal material, what would it be? Dimension Inx is in a place now where we could probably design that material.”
References
- bit.ly/odt210321
- bit.ly/odt210322
- bit.ly/odt210323
- bit.ly/odt210324
- bit.ly/odt210325
- bit.ly/odt210326
- bit.ly/odt210327
Mark Crawford is a full-time freelance business and marketing/communications writer based in Madison, Wis. His clients range from startups to global manufacturing leaders. He also writes a variety of feature articles for regional and national publications and is the author of five books.
