Mark Crawford, Contributing Writer11.17.21
Although orthopedic R&D is up, “elective” surgical procedures are being booked that had been delayed last year due to COVID-19; and new implants, devices, and instruments are in high demand, orthopedic device manufacturers are limited in their production output due to ongoing supply chain disruptions. Nearly every item in the supply chain is harder to get, sometimes with lead times as long as six months. In addition, the extreme excess demand/deficit has resulted in some big price increases by raw material suppliers, which are further impacting medical device manufacturers (MDMs). A shortage of qualified labor also adds to the production slowdown.
“Supply chain issues caused by the pandemic continue as suppliers struggle to catch up and find workers, but we have taken this into account and expanded our inventory so we have been able to ship a very large percentage of orders,” said Bing J. Carbone, president of Modern Plastics, a Shelton, Conn.-based provider of high-performance, medical-grade polymer stock shapes for the medical device industry.
Prices continue to escalate, especially for higher-demand materials.
“Many companies have absorbed the cost increases due to the economic environment, but sustaining this is difficult,” said Ronelle Decker, global market manager for life science for Omniseal Solutions, a Saint-Gobain business that provides advanced materials and solutions for the medical device and life sciences industries. “There is also increased inflation of raw material costs, especially for the metals and polymers used in orthopedic devices. It is very difficult today to predict a trend for raw materials requiring ongoing monitoring.”
Resins are especially in short supply and, in some cases, have doubled in price. This deficit, however, is not completely COVID-19-induced; it is also related to severe storms/hurricanes that have hit the prime areas of resin production. “Many of the refineries that produce these base resins have been shut down and are slow to re-open,” said Carbone. “With demand surging, resin suppliers and resin converters are also struggling to find employees so that they can return to full production and increase manufacturing capacity.”
Demand for metal from MDMs and their contract manufacturers (CMs) began to increase in December 2020 and, to date, 2021 demands are well above 2019 levels. “The mills are working extremely hard to respond to global demand across all markets,” added Ric Snyder, director of sales and marketing for Vested Metals International, a St. Augustine, Fla.-based provider of medical-grade metals for the orthopedic medical device market. “They are facing the same challenges that many other industries are, such as labor shortages and supply chain issues. It looks like we will be well into 2022 before the mills are caught up.”
In addition, materials suppliers tend to support their largest customers first, especially for high-volume production or specialized raw materials in certain grades.
“In terms of lead time, compared to aerospace, medical does not have the same volume and we tend to be pushed behind,” said Thomas Guéguen, general manager for Forecreu America, a Chicago, Ill.-based designer and manufacturer of cannulated bars made from various types of steels and titanium alloys for the orthopedic market. “Therefore, planification/anticipation is key and we work on projections and inventory replenishment to keep plenty of stock on our shelves for our customers.”
“It is the ‘perfect storm,’” added Carbone. “We are experiencing heavy advance blanket order placement for our medical-grade plastics and are fortunate that we can keep the flow of plastic product timely and consistent for our customers.”
Current Trends
Improving biocompatibility and patient outcomes have always been key forces driving the development of patient-specific solutions in the medical device industry, especially for minimally invasive procedures and robotic-assisted surgeries. Material properties are absolutely vital for advancing these technologies—not only because of the engineered chemical and mechanical characteristics of these materials, but also their biocompatibility with the human body. For example, materials continue to evolve to mitigate certain metal sensitivities in patients, such as nickel allergies, or classifications as toxic (such as cobalt levels as determined by the EU Medical Device Regulation).
“As a material producer, we see spine and robotics as the two areas within ortho with the largest opportunity for material advancement,” said Ray DeFrain, field metallurgist for the medical sector for Philadelphia-based Carpenter Technology, a melter and manufacturer of bar, wire, strip, plate, and powder in iron, nickel, cobalt, and titanium alloys. “Within the spine segment, there is growing adoption of additively manufactured titanium components as a replacement for polyetheretherketone [PEEK] and traditionally manufactured wrought products. More work is necessary to optimize these solutions as the industry learns more about this technology. With respect to robotics, OEMs are looking for tighter tolerances and stronger materials to support minimally invasive surgical [MIS] procedures.”
For implants, a top focus is developing materials that have improved osseointegrative properties. The goal is to maximize integration of the bone into the implant for improved patient outcomes and longer-lasting performance, with no loosening. Bioactive coatings have also been developed that prompt osseointegration, or have antibacterial properties that prevent post-surgical infections.
“During the last few years, improved osseointegration has been the goal behind many new development projects,” said Ulf Brogren, chief commercial officer for Promimic, a Gothenburg, Sweden-based provider of advanced materials for medical and orthopedic devices, especially implants. “A current trend is toward cementless solutions, especially for knee and shoulder implants. In spine, the choice of material depends on the properties of the implant and the type of osseointegration that is desired.”
Using the knowledge that human bone is made from nanoparticles of hydroxyapatite, MDMs are looking for related or new materials that improve integration between the implant and bone. “With the growing trend of 3D printing implants using micro-porous implant materials, it is possible to mimic the bone structure and then coat the implant with a nano-thin surface treatment like our HAnano Surface,” said Brogren. “This process creates an implant that has the right macro-, micro-, and nano-structure and roughness for enhanced osseointegration. We have proven, both pre-clinical and clinical, that these types of materials improve osseointegration, even for the most demanding patients with compromised bone situations, such as diabetic or metabolic patients.”
MDMs are also increasingly interested in self-lubricious materials such as silicone formulations or ultra-high molecular weight polyethylene (UHMPE)—a biocompatible and self-lubricating polyolefin. Using self-lubricating materials can streamline production and eliminate secondary processing steps. “We are also seeing replacement of metal components with lighter-weight plastic materials that can be custom-fit and designed for enhanced fluid, pressure, friction, and wear control,” said Decker. “Examples include surgical- and dental-powered hand pieces for rotary or reciprocating motion, as well as in-vitro diagnostics for wear and friction control.”
What OEMs Want
OEMs are constantly focused on quality, performance, and validations of materials and processes that will speed up regulatory approvals. A big challenge is determining the balance between undertaking advanced engineering of materials to meet design criteria and component functionality, versus the cost, speed of approval, and time to market for the project. Ideally the selected material will have the enhanced properties needed to meet the performance specs, as well as a solid track record so as not to slow down approval.
For legacy materials, quality is the top concern. MDMs want quality materials that consistently meet specs every time they are ordered. For new materials, higher-strength metals with good yield strength and improved fatigue are always being explored. “Any properties that allow a smaller part to be manufactured, but still offer the same or better strength and support to the patient, are always of interest to OEMs,” said Snyder.
For example, it is advantageous for the diameter of a dental implant to be as small as possible because it requires less bone removal, which means less trauma to the patient. Often, a patient’s alveolar ridge requires an alteration to ensure it can hold a sufficiently sized implant that will provide the strength needed for proper function. This procedure utilizes bone grafting, which can be an agonizing experience for the patient and requires additional time and expense.
“Developing higher-strength materials with excellent static and dynamic fatigue properties for applications such as dental implants allows for smaller diameter implants that perform the same, or better than, larger-diameter implants and improve the patient experience,” said Snyder.
Carbone noted that, in general, depending on the application, “the most commonly desired properties are dimensionally stable materials, high-tensile plastics, radiolucency, and specialty-filled grades of plastics for enhanced physical properties.”
Other common requests from orthopedic medical engineers include a modulus closer to that of bone, strength and toughness to support MIS by reducing implant or instrument footprint, improved wear resistance, and workpiece materials compatible with more complex methods of manufacturing, such as Internet of Things, six-axis, computer numerical control (CNC), or Swiss-style. MDMs are also interested in lightweight materials for surgical hand pieces and miniaturization for small micro-motors. “Plastics with excellent heat, chemical, and wear resistance, for example, must be able to withstand the combination of speed pressure for a surgical hand piece,” said Decker. “For components in a pneumatic motor, plastics must have good wear and friction control, resistant to wide variety of solvents and corrosives, and good thermal resistance.”
Waste reduction is always a top concern—not only does reducing scrap save time and money, it is beneficial to the environment and builds brand image. “We are seeing companies that we work with reduce material loss and maximize machine time by using creative forms of input material and engineer fixtures that allow multiple parts to be manufactured without interrupting the machine cycle, thereby reducing set-up time, ” said Snyder. “We are also seeing more CNC machine-loading robots on machine shop floors. In today’s labor market, these time-saving innovations are vital in reducing machine downtime.”
Material Advances
Many alloys have been developed by Carpenter Technology to support the needs of the medical community. For cobalt-chrome-molybdenum, Carpenter has developed seven variants to support improved machinability, forgeability, and diffusion bonding characteristics of surface coatings. “These advancements have positively affected the large joint and spinal markets,” said DeFrain.
Carpenter Technology is currently developing a minimum residual stress 17-4PH bar stock for some unique medical-machining applications to ensure consistency from bar to bar. This will ensure minimal deflection during the machining operation and open the door to advanced, hands-off manufacturing of complex and thin-wall geometries. In addition, some secondary operations may be able to be eliminated due to first-time-through acceptability. “This would be a game-changer for many of the medical component machining practices,” said DeFrain.
In the plastics field, Omniseal Solutions offers fluoropolymer compounds with variable temperature resistances that were not possible in the past—in cryogenics, for example, “these compounds can be developed to withstand lower temperatures suitable for cryogenic storage, coolers, and preservation,” said Decker.
Evonik has developed a new osteoconductive PEEK—VESTAKEEP Fusion—that improves the fusion between the bone and the implant. The osteoconductive properties were achieved by using a special functional additive—biphasic calcium phosphate, which allows bone cells to adhere to implants more quickly. “Calcium phosphates are a natural component of bone,” said Carbone. “If osteoblasts find body-like substances at the implant, they can dock there more easily, which positively influences osteointegration.”
VESTAKEEP Fusion is available as a granulate and as a semi-finished stock-shape product. Evonik is also developing a polymer filament based on PEEK in implant-grade quality that can be used with fused filament fabrication (FFF) to produce AM-manufactured components and medical implants.
Another segment of materials that is often the focus of significant R&D is coatings. For example, researchers at the Chalmers University of Technology in Sweden have created a new graphene coating that prevents bacterial infections in implants over long periods, using a special sustained-release feature.1 A new implant-coating process that greatly reduces risk of post-surgical infection was recently announced by the Fraunhofer Institute for Manufacturing Technology and Advanced Materials in Germany. Physical vapor deposition is used to apply a thin layer of silver to the implant, which is then dipped into an antibiotic solution that is customized to the needs of the individual patient. The antibiotic solution keeps any infections from developing immediately after surgery; the silver layer then releases bacteria-killing ions over the next several weeks, providing additional protection against infections throughout the healing process.2
Moving Forward
Supply chain issues, raw material price increases, continued material shortages, and long lead times will continue to plague the medical device industry into 2022. However, medical device companies have become more experienced and creative in sourcing materials over the last 18 months, which will hopefully minimize the impacts of supply chain disruption.
Meanwhile, R&D will go forward in multiple ways: pre-hardened materials, high-strength nickel-free implantable alloys, and 3D-printing methods and materials [for example, poly(L-lactide) biodegradable polymer, carbon-reinforced PEEK, and memory-shape alloys]. Research continues on how porosity can affect the physical properties of certain materials. More metallic components will be replaced by lighter-weight engineered plastics that are just as tough, without losing functionality.
More work also needs to be done to understand how the chemistry and quality of metal powders are altered during additive manufacturing processes. Typically, chemistry changes during the additive manufacturing process. This change can be due to vaporized elements or the increase in elements found naturally in the air (such as oxygen and nitrogen). “These changes can mean big differences in how a material and its final component performs,” said DeFrain. “There are challenges with cracking, build failures, and undesirable mechanical properties. In addition to the chemical variation, anisotropic grain size and mechanical properties can result from an additive process. Lastly, some alloys with reduced weldability have additional hurdles to overcome in additive processes and require alternatives or unique processing strategies. We produce additive powders with customized chemistry—within industry standards—to alleviate these challenges.”
Even though it has made tremendous gains over the last several years, AM is still far from perfect—for example, producing parts with the same properties and dimensions from start to finish, consistently, every time, is still a challenge. The purity of AM materials is also essential for creating consistent, clean parts with no residues or contamination. If the raw materials used in additive manufacturing are not of precisely controlled composition, additives and contaminants can migrate to the surface and result in unintended surface composition.
“Most OEMs typically do not fully understand how the dimensional tolerances of the material they are buying can have a major impact on the effectiveness of the devices they sell, as well as the total cost to produce them,” said Steve Tamasi, president of Boston Centerless, a Woburn, Mass.-based provider of medical-grade plastics, metals, and alloys for the orthopedic device market. “With more consistently, exacting tolerances, the process to produce products becomes much more stable and predictable, allowing for less interaction with various levels of labor—from the machine operators to quality to engineering to manufacturing management.”
The field of bioabsorbable metals is an intriguing area of development in orthopedic materials.
“These compounds are naturally absorbed by the body after they are no longer needed,” said Snyder. “They have shown the potential to prevent the need for secondary surgery, promote bone growth, allow for less trauma to the patient, and reduce complications and healthcare cost.”
Magnesium alloys are especially promising materials for use in absorbable implants. Biodegradable magnesium materials offer significantly enhanced mechanical properties for orthopedic applications compared to their biodegradable plastic counterparts; the drawback, however, is that magnesium and magnesium alloys degrade too quickly in the body and do not retain their mechanical properties long enough for most structural orthopedic applications. They also tend to be low strength and low ductility.
Collaboration for Innovation
Alloy innovation is not impossible for an MDM.
Materials companies often collaborate with MDMs to develop innovative or proprietary materials for specific applications or devices.
“Several OEMs have their own advanced materials groups, often focused on material that they have bought or licensed from universities or smaller companies,” said Brogren.
When they collaborate with materials companies, MDMs have greater quality and control, more focused expertise, and a shorter supply chain for developing their own advanced materials.
“Carpenter Technology works directly with OEMs or tier suppliers to address material advancement needs,” said DeFrain. “Advancements can be found through material innovation, both existing or new-to-world, unique processing strategies, and novel testing to support adoption.”
There are natural obstacles to alloy adoption within industry standards, as well as regulatory restrictions, processes, and approvals necessary for components adoption. Carpenter Technology helps MDMs with these processes and developing next-generation materials, as well as creating new Masterfile data for new materials and/or applications.
Precise information on the performance specifications, clinical applications, and operating environment is required to make the best material choice from the existing materials available. Some of these parameters include temperature, rotary, reciprocating or static motion, speed for rotary or reciprocating motion, friction and torque requirements, flexibility, pushability, and material or surface finish within the environment.
“We have developed over 500 formulations, mostly through co-development activities with our customers,” said Decker. “Custom components and materials are designed in-house where our experts and engineers provide a precise material solution for their critical applications. Some of our material solutions include lighter-weight material for surgical drills, materials that assist with noise reduction and reduce surgeon fatigue, enhanced wear and friction control, and the ability to custom design for precise fit, especially for minimally invasive, so the device designs can remain ergonomic.”
Vested Metals recently collaborated with an OEM on two molybdenum-based materials for a spinal application, with the intent of finding materials that maximized performance and reduced the product’s diameter. “Higher tensile strength, higher yield strength, and improved fatigue were the goals,” said Snyder.
Vested Metals located a mill source where the material was melted and processed to annealed centerless ground bar according to the OEM’s specifications. Vested Metals then worked with its network of partners to facilitate the cold-working and conversion of the material to smaller diameter, higher-strength bars.
“This material does present some challenges and we do not know yet if it will be successful in accomplishing its intended purpose, but it is a great example of how OEMs are looking for new materials to improve performance and patient outcomes,” said Snyder.
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.
“Supply chain issues caused by the pandemic continue as suppliers struggle to catch up and find workers, but we have taken this into account and expanded our inventory so we have been able to ship a very large percentage of orders,” said Bing J. Carbone, president of Modern Plastics, a Shelton, Conn.-based provider of high-performance, medical-grade polymer stock shapes for the medical device industry.
Prices continue to escalate, especially for higher-demand materials.
“Many companies have absorbed the cost increases due to the economic environment, but sustaining this is difficult,” said Ronelle Decker, global market manager for life science for Omniseal Solutions, a Saint-Gobain business that provides advanced materials and solutions for the medical device and life sciences industries. “There is also increased inflation of raw material costs, especially for the metals and polymers used in orthopedic devices. It is very difficult today to predict a trend for raw materials requiring ongoing monitoring.”
Resins are especially in short supply and, in some cases, have doubled in price. This deficit, however, is not completely COVID-19-induced; it is also related to severe storms/hurricanes that have hit the prime areas of resin production. “Many of the refineries that produce these base resins have been shut down and are slow to re-open,” said Carbone. “With demand surging, resin suppliers and resin converters are also struggling to find employees so that they can return to full production and increase manufacturing capacity.”
Demand for metal from MDMs and their contract manufacturers (CMs) began to increase in December 2020 and, to date, 2021 demands are well above 2019 levels. “The mills are working extremely hard to respond to global demand across all markets,” added Ric Snyder, director of sales and marketing for Vested Metals International, a St. Augustine, Fla.-based provider of medical-grade metals for the orthopedic medical device market. “They are facing the same challenges that many other industries are, such as labor shortages and supply chain issues. It looks like we will be well into 2022 before the mills are caught up.”
In addition, materials suppliers tend to support their largest customers first, especially for high-volume production or specialized raw materials in certain grades.
“In terms of lead time, compared to aerospace, medical does not have the same volume and we tend to be pushed behind,” said Thomas Guéguen, general manager for Forecreu America, a Chicago, Ill.-based designer and manufacturer of cannulated bars made from various types of steels and titanium alloys for the orthopedic market. “Therefore, planification/anticipation is key and we work on projections and inventory replenishment to keep plenty of stock on our shelves for our customers.”
“It is the ‘perfect storm,’” added Carbone. “We are experiencing heavy advance blanket order placement for our medical-grade plastics and are fortunate that we can keep the flow of plastic product timely and consistent for our customers.”
Current Trends
Improving biocompatibility and patient outcomes have always been key forces driving the development of patient-specific solutions in the medical device industry, especially for minimally invasive procedures and robotic-assisted surgeries. Material properties are absolutely vital for advancing these technologies—not only because of the engineered chemical and mechanical characteristics of these materials, but also their biocompatibility with the human body. For example, materials continue to evolve to mitigate certain metal sensitivities in patients, such as nickel allergies, or classifications as toxic (such as cobalt levels as determined by the EU Medical Device Regulation).
“As a material producer, we see spine and robotics as the two areas within ortho with the largest opportunity for material advancement,” said Ray DeFrain, field metallurgist for the medical sector for Philadelphia-based Carpenter Technology, a melter and manufacturer of bar, wire, strip, plate, and powder in iron, nickel, cobalt, and titanium alloys. “Within the spine segment, there is growing adoption of additively manufactured titanium components as a replacement for polyetheretherketone [PEEK] and traditionally manufactured wrought products. More work is necessary to optimize these solutions as the industry learns more about this technology. With respect to robotics, OEMs are looking for tighter tolerances and stronger materials to support minimally invasive surgical [MIS] procedures.”
For implants, a top focus is developing materials that have improved osseointegrative properties. The goal is to maximize integration of the bone into the implant for improved patient outcomes and longer-lasting performance, with no loosening. Bioactive coatings have also been developed that prompt osseointegration, or have antibacterial properties that prevent post-surgical infections.
“During the last few years, improved osseointegration has been the goal behind many new development projects,” said Ulf Brogren, chief commercial officer for Promimic, a Gothenburg, Sweden-based provider of advanced materials for medical and orthopedic devices, especially implants. “A current trend is toward cementless solutions, especially for knee and shoulder implants. In spine, the choice of material depends on the properties of the implant and the type of osseointegration that is desired.”
Using the knowledge that human bone is made from nanoparticles of hydroxyapatite, MDMs are looking for related or new materials that improve integration between the implant and bone. “With the growing trend of 3D printing implants using micro-porous implant materials, it is possible to mimic the bone structure and then coat the implant with a nano-thin surface treatment like our HAnano Surface,” said Brogren. “This process creates an implant that has the right macro-, micro-, and nano-structure and roughness for enhanced osseointegration. We have proven, both pre-clinical and clinical, that these types of materials improve osseointegration, even for the most demanding patients with compromised bone situations, such as diabetic or metabolic patients.”
MDMs are also increasingly interested in self-lubricious materials such as silicone formulations or ultra-high molecular weight polyethylene (UHMPE)—a biocompatible and self-lubricating polyolefin. Using self-lubricating materials can streamline production and eliminate secondary processing steps. “We are also seeing replacement of metal components with lighter-weight plastic materials that can be custom-fit and designed for enhanced fluid, pressure, friction, and wear control,” said Decker. “Examples include surgical- and dental-powered hand pieces for rotary or reciprocating motion, as well as in-vitro diagnostics for wear and friction control.”
What OEMs Want
OEMs are constantly focused on quality, performance, and validations of materials and processes that will speed up regulatory approvals. A big challenge is determining the balance between undertaking advanced engineering of materials to meet design criteria and component functionality, versus the cost, speed of approval, and time to market for the project. Ideally the selected material will have the enhanced properties needed to meet the performance specs, as well as a solid track record so as not to slow down approval.
For legacy materials, quality is the top concern. MDMs want quality materials that consistently meet specs every time they are ordered. For new materials, higher-strength metals with good yield strength and improved fatigue are always being explored. “Any properties that allow a smaller part to be manufactured, but still offer the same or better strength and support to the patient, are always of interest to OEMs,” said Snyder.
For example, it is advantageous for the diameter of a dental implant to be as small as possible because it requires less bone removal, which means less trauma to the patient. Often, a patient’s alveolar ridge requires an alteration to ensure it can hold a sufficiently sized implant that will provide the strength needed for proper function. This procedure utilizes bone grafting, which can be an agonizing experience for the patient and requires additional time and expense.
“Developing higher-strength materials with excellent static and dynamic fatigue properties for applications such as dental implants allows for smaller diameter implants that perform the same, or better than, larger-diameter implants and improve the patient experience,” said Snyder.
Carbone noted that, in general, depending on the application, “the most commonly desired properties are dimensionally stable materials, high-tensile plastics, radiolucency, and specialty-filled grades of plastics for enhanced physical properties.”
Other common requests from orthopedic medical engineers include a modulus closer to that of bone, strength and toughness to support MIS by reducing implant or instrument footprint, improved wear resistance, and workpiece materials compatible with more complex methods of manufacturing, such as Internet of Things, six-axis, computer numerical control (CNC), or Swiss-style. MDMs are also interested in lightweight materials for surgical hand pieces and miniaturization for small micro-motors. “Plastics with excellent heat, chemical, and wear resistance, for example, must be able to withstand the combination of speed pressure for a surgical hand piece,” said Decker. “For components in a pneumatic motor, plastics must have good wear and friction control, resistant to wide variety of solvents and corrosives, and good thermal resistance.”
Waste reduction is always a top concern—not only does reducing scrap save time and money, it is beneficial to the environment and builds brand image. “We are seeing companies that we work with reduce material loss and maximize machine time by using creative forms of input material and engineer fixtures that allow multiple parts to be manufactured without interrupting the machine cycle, thereby reducing set-up time, ” said Snyder. “We are also seeing more CNC machine-loading robots on machine shop floors. In today’s labor market, these time-saving innovations are vital in reducing machine downtime.”
Material Advances
Many alloys have been developed by Carpenter Technology to support the needs of the medical community. For cobalt-chrome-molybdenum, Carpenter has developed seven variants to support improved machinability, forgeability, and diffusion bonding characteristics of surface coatings. “These advancements have positively affected the large joint and spinal markets,” said DeFrain.
Carpenter Technology is currently developing a minimum residual stress 17-4PH bar stock for some unique medical-machining applications to ensure consistency from bar to bar. This will ensure minimal deflection during the machining operation and open the door to advanced, hands-off manufacturing of complex and thin-wall geometries. In addition, some secondary operations may be able to be eliminated due to first-time-through acceptability. “This would be a game-changer for many of the medical component machining practices,” said DeFrain.
In the plastics field, Omniseal Solutions offers fluoropolymer compounds with variable temperature resistances that were not possible in the past—in cryogenics, for example, “these compounds can be developed to withstand lower temperatures suitable for cryogenic storage, coolers, and preservation,” said Decker.
Evonik has developed a new osteoconductive PEEK—VESTAKEEP Fusion—that improves the fusion between the bone and the implant. The osteoconductive properties were achieved by using a special functional additive—biphasic calcium phosphate, which allows bone cells to adhere to implants more quickly. “Calcium phosphates are a natural component of bone,” said Carbone. “If osteoblasts find body-like substances at the implant, they can dock there more easily, which positively influences osteointegration.”
VESTAKEEP Fusion is available as a granulate and as a semi-finished stock-shape product. Evonik is also developing a polymer filament based on PEEK in implant-grade quality that can be used with fused filament fabrication (FFF) to produce AM-manufactured components and medical implants.
Another segment of materials that is often the focus of significant R&D is coatings. For example, researchers at the Chalmers University of Technology in Sweden have created a new graphene coating that prevents bacterial infections in implants over long periods, using a special sustained-release feature.1 A new implant-coating process that greatly reduces risk of post-surgical infection was recently announced by the Fraunhofer Institute for Manufacturing Technology and Advanced Materials in Germany. Physical vapor deposition is used to apply a thin layer of silver to the implant, which is then dipped into an antibiotic solution that is customized to the needs of the individual patient. The antibiotic solution keeps any infections from developing immediately after surgery; the silver layer then releases bacteria-killing ions over the next several weeks, providing additional protection against infections throughout the healing process.2
Moving Forward
Supply chain issues, raw material price increases, continued material shortages, and long lead times will continue to plague the medical device industry into 2022. However, medical device companies have become more experienced and creative in sourcing materials over the last 18 months, which will hopefully minimize the impacts of supply chain disruption.
Meanwhile, R&D will go forward in multiple ways: pre-hardened materials, high-strength nickel-free implantable alloys, and 3D-printing methods and materials [for example, poly(L-lactide) biodegradable polymer, carbon-reinforced PEEK, and memory-shape alloys]. Research continues on how porosity can affect the physical properties of certain materials. More metallic components will be replaced by lighter-weight engineered plastics that are just as tough, without losing functionality.
More work also needs to be done to understand how the chemistry and quality of metal powders are altered during additive manufacturing processes. Typically, chemistry changes during the additive manufacturing process. This change can be due to vaporized elements or the increase in elements found naturally in the air (such as oxygen and nitrogen). “These changes can mean big differences in how a material and its final component performs,” said DeFrain. “There are challenges with cracking, build failures, and undesirable mechanical properties. In addition to the chemical variation, anisotropic grain size and mechanical properties can result from an additive process. Lastly, some alloys with reduced weldability have additional hurdles to overcome in additive processes and require alternatives or unique processing strategies. We produce additive powders with customized chemistry—within industry standards—to alleviate these challenges.”
Even though it has made tremendous gains over the last several years, AM is still far from perfect—for example, producing parts with the same properties and dimensions from start to finish, consistently, every time, is still a challenge. The purity of AM materials is also essential for creating consistent, clean parts with no residues or contamination. If the raw materials used in additive manufacturing are not of precisely controlled composition, additives and contaminants can migrate to the surface and result in unintended surface composition.
“Most OEMs typically do not fully understand how the dimensional tolerances of the material they are buying can have a major impact on the effectiveness of the devices they sell, as well as the total cost to produce them,” said Steve Tamasi, president of Boston Centerless, a Woburn, Mass.-based provider of medical-grade plastics, metals, and alloys for the orthopedic device market. “With more consistently, exacting tolerances, the process to produce products becomes much more stable and predictable, allowing for less interaction with various levels of labor—from the machine operators to quality to engineering to manufacturing management.”
The field of bioabsorbable metals is an intriguing area of development in orthopedic materials.
“These compounds are naturally absorbed by the body after they are no longer needed,” said Snyder. “They have shown the potential to prevent the need for secondary surgery, promote bone growth, allow for less trauma to the patient, and reduce complications and healthcare cost.”
Magnesium alloys are especially promising materials for use in absorbable implants. Biodegradable magnesium materials offer significantly enhanced mechanical properties for orthopedic applications compared to their biodegradable plastic counterparts; the drawback, however, is that magnesium and magnesium alloys degrade too quickly in the body and do not retain their mechanical properties long enough for most structural orthopedic applications. They also tend to be low strength and low ductility.
Collaboration for Innovation
Alloy innovation is not impossible for an MDM.
Materials companies often collaborate with MDMs to develop innovative or proprietary materials for specific applications or devices.
“Several OEMs have their own advanced materials groups, often focused on material that they have bought or licensed from universities or smaller companies,” said Brogren.
When they collaborate with materials companies, MDMs have greater quality and control, more focused expertise, and a shorter supply chain for developing their own advanced materials.
“Carpenter Technology works directly with OEMs or tier suppliers to address material advancement needs,” said DeFrain. “Advancements can be found through material innovation, both existing or new-to-world, unique processing strategies, and novel testing to support adoption.”
There are natural obstacles to alloy adoption within industry standards, as well as regulatory restrictions, processes, and approvals necessary for components adoption. Carpenter Technology helps MDMs with these processes and developing next-generation materials, as well as creating new Masterfile data for new materials and/or applications.
Precise information on the performance specifications, clinical applications, and operating environment is required to make the best material choice from the existing materials available. Some of these parameters include temperature, rotary, reciprocating or static motion, speed for rotary or reciprocating motion, friction and torque requirements, flexibility, pushability, and material or surface finish within the environment.
“We have developed over 500 formulations, mostly through co-development activities with our customers,” said Decker. “Custom components and materials are designed in-house where our experts and engineers provide a precise material solution for their critical applications. Some of our material solutions include lighter-weight material for surgical drills, materials that assist with noise reduction and reduce surgeon fatigue, enhanced wear and friction control, and the ability to custom design for precise fit, especially for minimally invasive, so the device designs can remain ergonomic.”
Vested Metals recently collaborated with an OEM on two molybdenum-based materials for a spinal application, with the intent of finding materials that maximized performance and reduced the product’s diameter. “Higher tensile strength, higher yield strength, and improved fatigue were the goals,” said Snyder.
Vested Metals located a mill source where the material was melted and processed to annealed centerless ground bar according to the OEM’s specifications. Vested Metals then worked with its network of partners to facilitate the cold-working and conversion of the material to smaller diameter, higher-strength bars.
“This material does present some challenges and we do not know yet if it will be successful in accomplishing its intended purpose, but it is a great example of how OEMs are looking for new materials to improve performance and patient outcomes,” said Snyder.
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.
