Mark Crawford, Contributing Writer08.09.16
Now that 3D printing has settled into the consciousness of the medical device industry, and most people have a good idea of the incredible potential it offers, orthopedic companies are starting to focus on how to use additive manufacturing technologies like 3D printing in their research and development efforts, in more in-depth ways. Orthopedics is, in general, a cautious industry. In the beginning, 3D printing was limited to making prototypes, reducing iterations, and speeding up decision making. Now, however, more companies are seriously looking at additive manufacturing—especially 3D printing—as a way to make patient-specific products, as well as larger, more complex implants and devices, with higher production runs.
“We are starting to get past the 3D-printing hype and into a phase of sustainable growth for applications where additive manufacturing adds real value,” said Sebastian De Boodt, product portfolio manager for Materialise NV, a Leuven, Belgium-based provider of certified medical 3D printing solutions, including anatomical models and patient-specific products.
Additive manufacturing (AM) capabilities continue to evolve at a rapid pace, giving engineers and product designers the ability to create geometries that could not be manufactured otherwise, with minimal material waste and faster product development speeds. For example, research teams at Stryker Corp., a Kalamazoo, Mich.-based manufacturer of medical products and services, including implants, is using AM to combine highly porous structures with solid structural elements in designs for spinal implants that could not be manufactured before using traditional manufacturing techniques.
Other applications for AM in orthopedics include the production of patient-specific plastic surgical guides and standard titanium hip cups. Lima and Adler Ortho S.R.L., both Italian firms, have been leaders in making titanium hip cups. AM allows the creation of a porous layer that facilitates bone ingrowth without the need for coatings or post-processing, which makes AM cost-competitive with standard approaches. Other companies are starting to follow this lead, using AM for hip and spine implants. And, although the total volume is still small, there is increased production of patient-specific orthopedic implants, such as the hip revision systems or glenoid reconstruction implants manufactured by Materialise. This is where 3D printing really demonstrates its greatest value to date—allowing patient-specific production of highly complex implants, designed to match the geometry and mechanics of individual patients.
More companies are looking at adopting 3D printing as a volume manufacturing technology in the near future. In the past, many companies did not take full advantage of the design freedom that 3D printing offers; this is beginning to change, resulting in more intelligent implant designs with improved functionality, especially for patient-specific needs.
“For example, we expect to see the 3D printing of large joint orthopedic implants increase as the productivity of 3D printing technology grows year after year,” said Peter Mercelis, director of applied technologies for healthcare for 3D Systems, a global provider of 3D printing technologies and solutions. “In the past, 3D printing used to raise a lot of questions around mechanical integrity; this is no longer an issue with high-purity printing machines and appropriate heat treatments.”
What OEMs Want
OEMs are asking for better replication of bone models that mimic the complexity of real bone, including the range of hardness and geometry of cortical and cancellous bone, as well as marrow. Having the ability to integrate multiple textures that better match the complexity of living anatomy will improve surgical outcomes. This means improved osseointegration, which is high on the orthopedic wish list. For example, in lumbar spinal fusion procedures, advancement of bony fusion at the target levels is essential for successful clinical outcomes. This is dependent on creating a porous surface that enhances the biologic fixation potential of implants. Research is under way that will study what geometries and pore sizes provide the optimal environment for cells to attach and multiply within an implanted structure. With the capabilities of 3D printing, these designs are becoming increasingly complex—for example, incorporating osseoinductive bone scaffolds for improved short- and long-term implant fixation.
“Businesses often make the mistake of considering 3D printing for the simple replacement of an existing manufacturing technology, and this doesn’t always work,” said Greg Thompson, global product manager for 3D printing for Proto Labs, a Maple Plain, Minn.-based provider of 3D printing, computer numerical control (CNC) machining, and injection molding services. “The real value comes from enabling designs or design cycles previously unachievable via conventional methods. If the business is not considering fundamentally different processes or part designs, it will miss out on much of the benefit and opportunities for overall cost reduction and value enhancement.”
Despite the fact 3D printing and AM have brought exciting technologies to the forefront, they are evolving very rapidly, which has created some concerns among MDMs and contract manufacturers about maintaining validation of the process. Repeatable quality and full traceability of the production process are absolutely essential for validation. To ensure these requirements are met, AM equipment providers are introducing systems that capture the necessary data for validation. For example, Materialise has developed its own software program that captures and analyzes all key AM data (including machine parameters and log data), manages AM-specific production workflows, and automates AM process steps like part serialization. “This helps facilitate the certification process and ensures an efficient implementation of the AM production process,” said De Boodt.
Current Applications
More companies are incorporating 3D printing into their design processes. This and other additive manufacturing methods are being used to make a wide range of products, including prototypes and parts, surgical guides, medical models, various equipment, and both standard and custom implantable devices—especially knee, hip, and spine implants.
For example, Stryker’s Tritanium posterior lumbar cage received 510(k) clearance from the U.S. Food & Drug Administration (FDA) in November 2015. It aids in lumbar spinal fixation as an adjunct to fusion for patients with degenerative disc disease. The specific type of additive manufacturing technology used to build the cage is laser rapid manufacturing (LRM), which uses a focused laser beam to melt layers of metal powder in a fusion bed. This capability allowed the design team to create a unique material with precise porous structures that resemble cancellous bone, a type of spongy bone tissue found in vertebral bodies. After developing an innovative approach for modeling and manufacturing these porous structures using LRM, Stryker then collaborated with hardware and software companies to develop production-capable systems for processing the material.
Patients with complex traumas cannot always be treated successfully with standard implants or prostheses. For these situations, Materialise provides 3D-printed, patient-specific titanium hip, shoulder, and cranio-maxillofacial implants, which reduce time spent in the operating room, patient recovery time, and total costs. The implants are manufactured by selective laser melting of Grade-2 titanium powder. “The final implant is just part of a complete patient solution that includes in-depth 3D planning and a biomechanical simulation of the patient’s post-operative situation,” stated De Boodt.
3D Systems uses direct metal printing technology to manufacture acetabular implants for complex oncological hip resections. These are highly challenging applications, both because of the size and complexity of these large titanium implants, as well as the extreme time pressure for delivering the implant in the short period between the imaging and implant design phase and the actual tumor resection procedure.
“Direct metal printing is ideal for these situations because of the unlimited shape complexity, integrated bone scaffolds, ability for patient-specific designs, and the very short lead times that can be achieved,” said Mercelis. “Inclusion of fully controlled and reproducible porous scaffolds in orthopedic implants allows the tailoring of the mechanical properties of an implant to the surrounding bone, thereby reducing stress shielding while still ensuring sufficient strength of the implant.”
Surgeons also turn to 3D printing when time is short for life-saving surgery. For example, Alphaform AG, a Germany-based rapid-prototyping company, teamed up with Instrumentaria d.d., a Croatian manufacturer of medical instruments, to design and manufacture a hip implant for a 15-year-old boy. An especially aggressive form of bone cancer had destroyed the teenager‘s hip and his doctors were fearful the cancer would spread quickly from the hip area, so it was paramount that the implant surgery be completed as soon as possible.
Using EOS 3D printing equipment, the team designed and manufactured a precise-fitting, lightweight titanium hip implant. The biggest challenge was the short period of planning and production time before the imminent operation. The titanium implant was engineered to have a large number of cavities in otherwise solid parts to reduce weight, a design that can only be achieved through additive manufacturing (precision casting or conventional milling cannot achieve such a complex shape). The challenge with the integration of the empty spaces was finding the correct mix of stability and weight reduction, because the implant also needed to withstand a high degree of physical stress. The process, from the initial computer sketches to the final implant, took only six weeks, followed by a successful surgery and full patient recovery.
Michael Gaisford, director of marketing for the medical solutions team at Stratasys Ltd., an Eden Prairie, Minn.-based manufacturer of 3D printers and materials for production and prototyping, notes a significant increase in the use of 3D printing by hospitals and physicians. Applications include using 3D printers to plan complex surgeries (especially revisions and unusual anatomy), optimize therapy, improve efficiencies in the operating room, and shorten recovery times. Medical manufacturers are also using 3D printing to create cutting and drill guides that are patient-specific to enhance the accuracy and efficiency of surgical procedures. Custom implants are also being 3D printed to match patient anatomy and treat pathology.
“Although these devices are typically manufactured by medical device companies, the patient scans are gathered by physicians, and the data connection from scan to patient-specific design is either done in-house or by service bureaus,” said Gaisford.
More hospitals are setting up 3D printing centers to service the entire hospital, across all specialties. The centers act as a “platform technology” that enable procedure planning, physician training and education, rapid creation of unique research tools, and testing of new medical devices. “3D models are being increasingly used for education and training of physicians to learn new techniques and devices, often from patient scans that include the real pathology, a key differentiator compared to using animal models or cadavers that don’t have the disease pathology,” added Gaisford. “Physicians are therefore exposed to the full range of clinical complexity with models created from real patient examples.”
A related advancement that accelerates the 3D printing process is the continued improvement of auto-segmentation software solutions. Historically, if a patient-specific model was needed from a magnetic resonance (MRI) or computed tomography (CT) image, it required laborious manual segmentation software. Today, auto-segmentation software is getting to the point where health imaging intelligence firms like Vital Images Inc. are streamlining the 3D printing process by integrating the process of converting patient scans with the software that drives 3D printing equipment.
Regulatory Matters
So far, the FDA has cleared more than 85 applications for 3D-printed devices, though none have been for high-risk devices requiring premarket approval. In general, the FDA is looking at 3D printing and AM devices with the same requirements as other medical devices, and views 3D printing as another enabling technology similar to other advanced manufacturing methods, such as CNC machining, that does not require being put in a class by itself or facing more intense scrutiny.
In a recently published position piece in the 3D Printing in Medicine journal, materials scientist Matthew Di Prima with the FDA’s Center for Devices and Radiological Health wrote that “the software used to generate the 3D model of the patient anatomy is evaluated by the FDA to assess the accuracy of the 3D volume reconstructed from image slices; however, the printer used to print the 3D component is outside of the scope of FDA review, much like an office’s laser printer would be when printing a PDF image.” This statement confirms the position that the FDA is not regulating 3D printing any differently than any other manufacturing technique.
It’s good news to the medical device industry that the FDA is embracing AM technology and trying to collaborate with industry to deliver new orthopedic AM products into the market in a safe and cost-effective way. In May, the FDA released its draft guidance for 3D-printed medical devices entitled “Technical Considerations for Additive Manufactured Devices.”
Although it is a good start, the guidance does have some limitations in scope—for example, “it does not address the incorporation of biological, cellular, or tissue-based products in the AM process which, as the agency has noted, may require additional regulatory and manufacturing process considerations and/or different regulatory pathways,” wrote attorneys Jordan T. Cohen and Joanne S. Hawana on www.lexology.com. “The agency also clarifies that point-of-care device manufacturing—that is, the manufacturing of a device in a hospital or in doctors' offices rather than at a manufacturing facility—may raise additional technical considerations.”
They also note that, because the guidance does not address point-of-care applications of AM, it therefore leaves unanswered “the question of whether a hospital or clinic using AM will be considered a manufacturer that is subject to FDA’s regulatory oversight. The agency also fails to provide guidance on when manufacturers with previously cleared AM devices will need to submit new premarket 510(k) applications. This question is particularly salient in the context of AM, due to a manufacturer’s unique ability to tweak aspects of the manufacturing process, including the starting materials and specific synthesizing procedures.”
More clarification will likely be forthcoming after the comment period closes (Aug. 8). In the meantime, the document provides a good, general overview of the aspects that require specific attention when using 3D printing for the manufacturing of medical devices. MDMs have already adopted many of the guidelines suggested in the document, such as thorough process validation and raw material characterization.
“This document should help companies new to 3D printing to understand the technology and the specific challenges and risks it introduces,” said Mercelis. “I would also expect that clear guidelines will also lead to faster approval of premarket applications by the FDA, allowing companies to bring novel medical devices faster to market.”
(Editor’s note: For more on the FDA’s AM guidance document, view the latest Mike on Medtech video on the Medical Product Outsourcing website at http://bit.ly/mpomike1.)
On the Horizon
Over the last few years, the medical device industry has gained a better understanding of the incredible flexibility that additive manufacturing and 3D printing technologies offer in terms of material properties, surface finish, and feature resolution. “As a result,” said Thompson, “we are seeing better designs and customers are able to take advantage of the benefits of 3D printing—incorporating more complex designs, reducing the number of tools required, accelerating design iterations, and getting to market faster.”
For example, metal 3D printing can be used to make metal implants highly porous to achieve radiolucency to evaluate bone ingrowth using radiographs. Radiography “inspection windows” are already integrated in some products on the market today. “Another benefit from AM that is not yet being fully utilized in most products today is the ability to tailor the local stiffness for optimized bone loading and to avoid stress shielding,” said Mercelis. “At the same time, the geometric freedom of AM lends itself to design monolithic implant designs that still allow for motion—for example, based on leaf spring-like designs.”
Other AM design benefits are the unlimited shape complexities, integrated bone scaffolds, ability for patient-specific designs, and possibly even the integration of internal transportation channels and/or cavities for time- and dose-controlled drug release, which has great potential for reducing the risk of peri-implant infections.
One of the greatest challenges for AM will be producing materials that match the full range of hardness of living tissue. For example, cortical bone can be as hard as 20 Gpa with bone marrow that is as soft as Shore A 5. Being able to replicate this full range is a huge technical challenge. These and other materials—such as resorbables, which provide temporary stability in the patient while the native bone gradually recovers and attaches to the implant—will face heightened scrutiny in the regulatory market approval process. Although resorbable materials have not yet been applied in orthopedics, they are getting plenty of attention. “With the recent success of using polycaprolactone (PCL) for the 3D printing of tracheal splints to treat babies, PCL may be the first resorbable material that makes its way into orthopedics,” said De Boodt.
Full integration of all tools required to implement 3D printing will be the next big wave of advancement. Print speed is only a very small part of the problem (and something all manufacturers are addressing). With 3D printers designed to print in a non-attended, “lights out” mode, “what really matters is the time orthopedists, biomedical engineers, or radiologists spend on obtaining and preparing digital scans of patients for printing,” said Gaisford. “The integration of business productivity software, plug-and-play hardware, and computer power has transformed the PC industry—from hours to install a printer to only taking a few seconds. 3D-printing companies, open-source collaborations, and evolving partnerships are driving the ecosystem evolution to remove the biggest time constraint—the human-guided preparation of data.”
Mercelis expects further increases in AM productivity in the near future by using multiple lasers, larger build areas, smart scanning strategies, and automated powder handling. As the technology improves and productivity increases, 3D printing will be used more for volume manufacturing of large joint implants, where currently productivity and cost are limiting factors.
“More patient-specific implants will be manufactured in the future, which we are already seeing in custom hip revision surgery,” he added. “This will be combined with surgical guides to transfer the treatment plan to the patient and anatomical models for optimal surgery preparation to deliver truly personalized treatment with optimal outcome.”
“As with any technology, businesses should consider 3D printing within the context of their own products and processes,” added Thompson. “Despite much of the hype implying that 3D printing will replace how we manufacture now, businesses must consider how 3D printing might enable new designs, approaches, and processes. Since 3D printing doesn’t require tooling, and part cost isn’t highly dependent on complexity, it can be a highly valuable tool to open up a whole new product mix for many companies across the healthcare community.”
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. Contact him at mark.crawford@charter.net.
“We are starting to get past the 3D-printing hype and into a phase of sustainable growth for applications where additive manufacturing adds real value,” said Sebastian De Boodt, product portfolio manager for Materialise NV, a Leuven, Belgium-based provider of certified medical 3D printing solutions, including anatomical models and patient-specific products.
Additive manufacturing (AM) capabilities continue to evolve at a rapid pace, giving engineers and product designers the ability to create geometries that could not be manufactured otherwise, with minimal material waste and faster product development speeds. For example, research teams at Stryker Corp., a Kalamazoo, Mich.-based manufacturer of medical products and services, including implants, is using AM to combine highly porous structures with solid structural elements in designs for spinal implants that could not be manufactured before using traditional manufacturing techniques.
Other applications for AM in orthopedics include the production of patient-specific plastic surgical guides and standard titanium hip cups. Lima and Adler Ortho S.R.L., both Italian firms, have been leaders in making titanium hip cups. AM allows the creation of a porous layer that facilitates bone ingrowth without the need for coatings or post-processing, which makes AM cost-competitive with standard approaches. Other companies are starting to follow this lead, using AM for hip and spine implants. And, although the total volume is still small, there is increased production of patient-specific orthopedic implants, such as the hip revision systems or glenoid reconstruction implants manufactured by Materialise. This is where 3D printing really demonstrates its greatest value to date—allowing patient-specific production of highly complex implants, designed to match the geometry and mechanics of individual patients.
More companies are looking at adopting 3D printing as a volume manufacturing technology in the near future. In the past, many companies did not take full advantage of the design freedom that 3D printing offers; this is beginning to change, resulting in more intelligent implant designs with improved functionality, especially for patient-specific needs.
“For example, we expect to see the 3D printing of large joint orthopedic implants increase as the productivity of 3D printing technology grows year after year,” said Peter Mercelis, director of applied technologies for healthcare for 3D Systems, a global provider of 3D printing technologies and solutions. “In the past, 3D printing used to raise a lot of questions around mechanical integrity; this is no longer an issue with high-purity printing machines and appropriate heat treatments.”
What OEMs Want
OEMs are asking for better replication of bone models that mimic the complexity of real bone, including the range of hardness and geometry of cortical and cancellous bone, as well as marrow. Having the ability to integrate multiple textures that better match the complexity of living anatomy will improve surgical outcomes. This means improved osseointegration, which is high on the orthopedic wish list. For example, in lumbar spinal fusion procedures, advancement of bony fusion at the target levels is essential for successful clinical outcomes. This is dependent on creating a porous surface that enhances the biologic fixation potential of implants. Research is under way that will study what geometries and pore sizes provide the optimal environment for cells to attach and multiply within an implanted structure. With the capabilities of 3D printing, these designs are becoming increasingly complex—for example, incorporating osseoinductive bone scaffolds for improved short- and long-term implant fixation.
“Businesses often make the mistake of considering 3D printing for the simple replacement of an existing manufacturing technology, and this doesn’t always work,” said Greg Thompson, global product manager for 3D printing for Proto Labs, a Maple Plain, Minn.-based provider of 3D printing, computer numerical control (CNC) machining, and injection molding services. “The real value comes from enabling designs or design cycles previously unachievable via conventional methods. If the business is not considering fundamentally different processes or part designs, it will miss out on much of the benefit and opportunities for overall cost reduction and value enhancement.”
Despite the fact 3D printing and AM have brought exciting technologies to the forefront, they are evolving very rapidly, which has created some concerns among MDMs and contract manufacturers about maintaining validation of the process. Repeatable quality and full traceability of the production process are absolutely essential for validation. To ensure these requirements are met, AM equipment providers are introducing systems that capture the necessary data for validation. For example, Materialise has developed its own software program that captures and analyzes all key AM data (including machine parameters and log data), manages AM-specific production workflows, and automates AM process steps like part serialization. “This helps facilitate the certification process and ensures an efficient implementation of the AM production process,” said De Boodt.
Current Applications
More companies are incorporating 3D printing into their design processes. This and other additive manufacturing methods are being used to make a wide range of products, including prototypes and parts, surgical guides, medical models, various equipment, and both standard and custom implantable devices—especially knee, hip, and spine implants.
For example, Stryker’s Tritanium posterior lumbar cage received 510(k) clearance from the U.S. Food & Drug Administration (FDA) in November 2015. It aids in lumbar spinal fixation as an adjunct to fusion for patients with degenerative disc disease. The specific type of additive manufacturing technology used to build the cage is laser rapid manufacturing (LRM), which uses a focused laser beam to melt layers of metal powder in a fusion bed. This capability allowed the design team to create a unique material with precise porous structures that resemble cancellous bone, a type of spongy bone tissue found in vertebral bodies. After developing an innovative approach for modeling and manufacturing these porous structures using LRM, Stryker then collaborated with hardware and software companies to develop production-capable systems for processing the material.
Patients with complex traumas cannot always be treated successfully with standard implants or prostheses. For these situations, Materialise provides 3D-printed, patient-specific titanium hip, shoulder, and cranio-maxillofacial implants, which reduce time spent in the operating room, patient recovery time, and total costs. The implants are manufactured by selective laser melting of Grade-2 titanium powder. “The final implant is just part of a complete patient solution that includes in-depth 3D planning and a biomechanical simulation of the patient’s post-operative situation,” stated De Boodt.
3D Systems uses direct metal printing technology to manufacture acetabular implants for complex oncological hip resections. These are highly challenging applications, both because of the size and complexity of these large titanium implants, as well as the extreme time pressure for delivering the implant in the short period between the imaging and implant design phase and the actual tumor resection procedure.
“Direct metal printing is ideal for these situations because of the unlimited shape complexity, integrated bone scaffolds, ability for patient-specific designs, and the very short lead times that can be achieved,” said Mercelis. “Inclusion of fully controlled and reproducible porous scaffolds in orthopedic implants allows the tailoring of the mechanical properties of an implant to the surrounding bone, thereby reducing stress shielding while still ensuring sufficient strength of the implant.”
Surgeons also turn to 3D printing when time is short for life-saving surgery. For example, Alphaform AG, a Germany-based rapid-prototyping company, teamed up with Instrumentaria d.d., a Croatian manufacturer of medical instruments, to design and manufacture a hip implant for a 15-year-old boy. An especially aggressive form of bone cancer had destroyed the teenager‘s hip and his doctors were fearful the cancer would spread quickly from the hip area, so it was paramount that the implant surgery be completed as soon as possible.
Using EOS 3D printing equipment, the team designed and manufactured a precise-fitting, lightweight titanium hip implant. The biggest challenge was the short period of planning and production time before the imminent operation. The titanium implant was engineered to have a large number of cavities in otherwise solid parts to reduce weight, a design that can only be achieved through additive manufacturing (precision casting or conventional milling cannot achieve such a complex shape). The challenge with the integration of the empty spaces was finding the correct mix of stability and weight reduction, because the implant also needed to withstand a high degree of physical stress. The process, from the initial computer sketches to the final implant, took only six weeks, followed by a successful surgery and full patient recovery.
Michael Gaisford, director of marketing for the medical solutions team at Stratasys Ltd., an Eden Prairie, Minn.-based manufacturer of 3D printers and materials for production and prototyping, notes a significant increase in the use of 3D printing by hospitals and physicians. Applications include using 3D printers to plan complex surgeries (especially revisions and unusual anatomy), optimize therapy, improve efficiencies in the operating room, and shorten recovery times. Medical manufacturers are also using 3D printing to create cutting and drill guides that are patient-specific to enhance the accuracy and efficiency of surgical procedures. Custom implants are also being 3D printed to match patient anatomy and treat pathology.
“Although these devices are typically manufactured by medical device companies, the patient scans are gathered by physicians, and the data connection from scan to patient-specific design is either done in-house or by service bureaus,” said Gaisford.
More hospitals are setting up 3D printing centers to service the entire hospital, across all specialties. The centers act as a “platform technology” that enable procedure planning, physician training and education, rapid creation of unique research tools, and testing of new medical devices. “3D models are being increasingly used for education and training of physicians to learn new techniques and devices, often from patient scans that include the real pathology, a key differentiator compared to using animal models or cadavers that don’t have the disease pathology,” added Gaisford. “Physicians are therefore exposed to the full range of clinical complexity with models created from real patient examples.”
A related advancement that accelerates the 3D printing process is the continued improvement of auto-segmentation software solutions. Historically, if a patient-specific model was needed from a magnetic resonance (MRI) or computed tomography (CT) image, it required laborious manual segmentation software. Today, auto-segmentation software is getting to the point where health imaging intelligence firms like Vital Images Inc. are streamlining the 3D printing process by integrating the process of converting patient scans with the software that drives 3D printing equipment.
Regulatory Matters
So far, the FDA has cleared more than 85 applications for 3D-printed devices, though none have been for high-risk devices requiring premarket approval. In general, the FDA is looking at 3D printing and AM devices with the same requirements as other medical devices, and views 3D printing as another enabling technology similar to other advanced manufacturing methods, such as CNC machining, that does not require being put in a class by itself or facing more intense scrutiny.
In a recently published position piece in the 3D Printing in Medicine journal, materials scientist Matthew Di Prima with the FDA’s Center for Devices and Radiological Health wrote that “the software used to generate the 3D model of the patient anatomy is evaluated by the FDA to assess the accuracy of the 3D volume reconstructed from image slices; however, the printer used to print the 3D component is outside of the scope of FDA review, much like an office’s laser printer would be when printing a PDF image.” This statement confirms the position that the FDA is not regulating 3D printing any differently than any other manufacturing technique.
It’s good news to the medical device industry that the FDA is embracing AM technology and trying to collaborate with industry to deliver new orthopedic AM products into the market in a safe and cost-effective way. In May, the FDA released its draft guidance for 3D-printed medical devices entitled “Technical Considerations for Additive Manufactured Devices.”
Although it is a good start, the guidance does have some limitations in scope—for example, “it does not address the incorporation of biological, cellular, or tissue-based products in the AM process which, as the agency has noted, may require additional regulatory and manufacturing process considerations and/or different regulatory pathways,” wrote attorneys Jordan T. Cohen and Joanne S. Hawana on www.lexology.com. “The agency also clarifies that point-of-care device manufacturing—that is, the manufacturing of a device in a hospital or in doctors' offices rather than at a manufacturing facility—may raise additional technical considerations.”
They also note that, because the guidance does not address point-of-care applications of AM, it therefore leaves unanswered “the question of whether a hospital or clinic using AM will be considered a manufacturer that is subject to FDA’s regulatory oversight. The agency also fails to provide guidance on when manufacturers with previously cleared AM devices will need to submit new premarket 510(k) applications. This question is particularly salient in the context of AM, due to a manufacturer’s unique ability to tweak aspects of the manufacturing process, including the starting materials and specific synthesizing procedures.”
More clarification will likely be forthcoming after the comment period closes (Aug. 8). In the meantime, the document provides a good, general overview of the aspects that require specific attention when using 3D printing for the manufacturing of medical devices. MDMs have already adopted many of the guidelines suggested in the document, such as thorough process validation and raw material characterization.
“This document should help companies new to 3D printing to understand the technology and the specific challenges and risks it introduces,” said Mercelis. “I would also expect that clear guidelines will also lead to faster approval of premarket applications by the FDA, allowing companies to bring novel medical devices faster to market.”
(Editor’s note: For more on the FDA’s AM guidance document, view the latest Mike on Medtech video on the Medical Product Outsourcing website at http://bit.ly/mpomike1.)
On the Horizon
Over the last few years, the medical device industry has gained a better understanding of the incredible flexibility that additive manufacturing and 3D printing technologies offer in terms of material properties, surface finish, and feature resolution. “As a result,” said Thompson, “we are seeing better designs and customers are able to take advantage of the benefits of 3D printing—incorporating more complex designs, reducing the number of tools required, accelerating design iterations, and getting to market faster.”
For example, metal 3D printing can be used to make metal implants highly porous to achieve radiolucency to evaluate bone ingrowth using radiographs. Radiography “inspection windows” are already integrated in some products on the market today. “Another benefit from AM that is not yet being fully utilized in most products today is the ability to tailor the local stiffness for optimized bone loading and to avoid stress shielding,” said Mercelis. “At the same time, the geometric freedom of AM lends itself to design monolithic implant designs that still allow for motion—for example, based on leaf spring-like designs.”
Other AM design benefits are the unlimited shape complexities, integrated bone scaffolds, ability for patient-specific designs, and possibly even the integration of internal transportation channels and/or cavities for time- and dose-controlled drug release, which has great potential for reducing the risk of peri-implant infections.
One of the greatest challenges for AM will be producing materials that match the full range of hardness of living tissue. For example, cortical bone can be as hard as 20 Gpa with bone marrow that is as soft as Shore A 5. Being able to replicate this full range is a huge technical challenge. These and other materials—such as resorbables, which provide temporary stability in the patient while the native bone gradually recovers and attaches to the implant—will face heightened scrutiny in the regulatory market approval process. Although resorbable materials have not yet been applied in orthopedics, they are getting plenty of attention. “With the recent success of using polycaprolactone (PCL) for the 3D printing of tracheal splints to treat babies, PCL may be the first resorbable material that makes its way into orthopedics,” said De Boodt.
Full integration of all tools required to implement 3D printing will be the next big wave of advancement. Print speed is only a very small part of the problem (and something all manufacturers are addressing). With 3D printers designed to print in a non-attended, “lights out” mode, “what really matters is the time orthopedists, biomedical engineers, or radiologists spend on obtaining and preparing digital scans of patients for printing,” said Gaisford. “The integration of business productivity software, plug-and-play hardware, and computer power has transformed the PC industry—from hours to install a printer to only taking a few seconds. 3D-printing companies, open-source collaborations, and evolving partnerships are driving the ecosystem evolution to remove the biggest time constraint—the human-guided preparation of data.”
Mercelis expects further increases in AM productivity in the near future by using multiple lasers, larger build areas, smart scanning strategies, and automated powder handling. As the technology improves and productivity increases, 3D printing will be used more for volume manufacturing of large joint implants, where currently productivity and cost are limiting factors.
“More patient-specific implants will be manufactured in the future, which we are already seeing in custom hip revision surgery,” he added. “This will be combined with surgical guides to transfer the treatment plan to the patient and anatomical models for optimal surgery preparation to deliver truly personalized treatment with optimal outcome.”
“As with any technology, businesses should consider 3D printing within the context of their own products and processes,” added Thompson. “Despite much of the hype implying that 3D printing will replace how we manufacture now, businesses must consider how 3D printing might enable new designs, approaches, and processes. Since 3D printing doesn’t require tooling, and part cost isn’t highly dependent on complexity, it can be a highly valuable tool to open up a whole new product mix for many companies across the healthcare community.”
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. Contact him at mark.crawford@charter.net.