Ranica Arrowsmith, Associate Editor09.15.15
Testing is the workhorse of the medical device supply chain. It exists at the disposal of, and in response to, whatever materials science, manufacturing processes or pharmaceutical (in combination devices) technology advances dictate. Testing service providers have to constantly adapt to advancements in device technology, and have to do it well and fast. Without testing and validation, the device cannot make it to market—and if done imperfectly, recalls and punitive actions are risked.
The key, experts in testing note, is that an off-the-shelf approach to testing does not work for orthopedic devices. Technology is advancing so rapidly that testing must be approached on an individual basis customer to customer. As much as products that appear to be the same—such as screws or plate systems—differ, so do customers. John Bolinder notes that Nelson Laboratories Inc. “looks beyond the test” to meet unique challenges from each customer, as well as regulatory requirements, head on and effectively.
Orthopedic Design & Technology’s expert sources came together to form a cohesive picture of how orthopedic device testing service providers are adapting to fast-changing landscapes; how they deal with new OEM (original equipment manufacturer) demands; and how they see testing services progressing and changing in the future. For instance, additive manufacturing is having an impact on how the companies approach testing. Experimentation with newer, perhaps cheaper materials in 3-D printing are posing challenges such as how to deal with more porous coatings. Also, those in the field of biologics will find an expanding job market as orthopedic devices using tissue, cell or gene-based therapies become more prominent. Testing such devices requires a specific skill and education set. In this vein, combination products—those that integrate hardware and pharmaceuticals—are on the rise, and will require experts in these crossover fields to test them adequately.
Experts at the roundtable include:
Jarret Wright, thermal, physical, and microscopy lab manager for Polymer Solutions Incorporated, a Christiansburg, Va.-based materials analysis and testing lab. The most common orthopedic products the company tests are bioabsorbable devices such as screws, tacks, pins, rods and plates. Wright notes that the chemical and physical properties of these products are heavily regulated because they perform as a medical device as well a as a drug.
Maciej Jakucki, department manager of medical device testing for Element Materials Technology in Cincinnati, Ohio.
Headquartered in London, United Kingdom, Element's team of over 1,800 "engaged experts" provide materials testing, product qualification, and failure analysis services in 51 laboratories throughout the United States and Europe. In the orthopedic space, Element performs mechanical testing for feasibility studies and regulatory submission purposes. Its most commonly tested devices include hip, knee, spine, and shoulder implants along with a wide variety of trauma, maxillofacial and dental devices.
Linda K. Hansen, Ph.D., scientific director of custom studies at WuXi AppTec. The company’s U.S. headquarters are located in St. Paul, Minn., with additional U.S. testing facilities in Atlanta, Ga., and Philadelphia, Pa. WuXi AppTec offers several areas of testing and services in the orthopedic area, from standardized osteoinductivity tests to custom pre-clinical efficacy studies, as well as tissue-based orthopedic product manufacturing.
John Bolinder, Alexa Tatarian and Thor Rollins, vice president of marketing and communications, study director in the chemistry department, and biocompatibility specialist and consulting manager, respectively, for Salt Lake City, Utah-based Nelson Laboratories Inc. Nelson Laboratories provides biocompatibility, sterilization validation, reuse and cleaning validation services, among others, on a wide range of orthopedic device types including surgical kits and trays, total joint, hip and knee implants, and small-bone devices such as bone screws.
Gary Socola, president of Highpower Validation Testing & Lab Services Inc. The firm’s testing services focus mainly on reusable medical devices that require cleaning, packaging and sterilization between patients. The company is headquartered in Rochester, N.Y.
ODT: Do you have an overall company philosophy when it comes to testing?
Jarret Wright: Polymer Solutions has an overall philosophy of quality and integrity. As a third-party testing lab our customers depend on precise and accurate results every time. We have a substantial amount of training and quality assurance procedures to ensure that we are able to deliver exactly that. There is also a philosophy that happy scientists do good science. Every Friday we have a company breakfast, and each month there are company events that foster fun and friendly interactions. We recognize that our work is a blend of strict scientific rigor but also creative thinking to tackle our clients’ most difficult materials challenges.
Maciej Jakucki: Element’s mission is to become the world’s most trusted testing partner. To achieve this, our testing philosophy is to be more than just a vendor to our clients. By providing pre-project consulting and review, we ensure that all interested parties are on the same page with the goals and objectives of each project. After testing, we provide comprehensive test reports and make ourselves available for discussion of results. This collaborative process leads to timely, accurate results that our customers can trust.
Linda Hansen: We aim to serve the client along the full path of product development from conception to pre-clinical regulatory approval. We believe in developing the best test plans to meet our customers’ specific needs, we take time to really understand those needs and develop our test plan accordingly. We don’t believe in a one-size fits all—we customize our approach.
Thor Rollins: We always consider what’s best for each client; devices which appear to be the same may have very different testing routes depending on the customer. Large medical device companies may benefit more from a reduced timeline where a small startup might be looking at the most cost effective solutions available. We make it a point to understand the client’s primary pain points so we can provide the most creative testing solutions for their unique needs.
Gary Socola: Yes, we take the business of medical device validations very seriously. We like to think of ourselves as an extension of our customers’ companies. There are plenty of laboratories that have a tremendous number of tests available that they can perform on a single-use or reusable medical device. We are not one of those laboratories. We want to be considered experts at what we do and we have found that our customers prefer to have a laboratory that they consider to be experts in reusable medical device packaging, cleaning and sterilization efficacy testing.
Because we specialize in cleaning, packaging and sterilization efficacy validation testing, we are extremely in tune with what is required from each part of the world and more importantly what changes are occurring right now at the U.S. Food and Drug Administration’s (FDA’s) Office of Device Evaluation.
ODT: What is your approach when starting work with a new customer?
Wright: It is very important for us to have a clear understanding of the problem or other need for testing. It is also important for the client to have a clear understanding of what results the analyses will provide. This two-way communication allows us to work together toward the solution. We clarify and work collaboratively with our clients to ensure success. Each client has a project manager who is their direct point of contact and serves as a liaison between them and our labs. Since we offer so many testing capabilities under one roof we find one technical point of contact ensures that start to finish, our entire team remains on the same page and exceeds our clients’ expectations.
Jakucki: We will spend time up-front with our new customers, taking the initiative to explain our process and the deliverables they can expect. In addition, we take the time to fully understand our client’s goals and ideas in order to help identify potential issues and share our expertise. New clients are often looking to learn as much as they can about test methods and new developments.
Our participation in ASTM (American Society for Testing and Materials) allows Element to be at the forefront of method development and, as such, direct our clients through successful testing projects.
Hansen: It is our goal to build strong relationships, partnerships with our customers. That starts by listening to fully understand the unique product or challenge that our customer is facing. We believe in transparency and accomplish that by establishing a key point of contact for customer interface which allows for efficient and effective communication of key details. Our technical staff is available to offer support, troubleshoot along the way and ensure the testing meets our customers’ goals.
John Bolinder: Ideally we take time to understand the product life cycle, consulting with the client to understand where they are in their product development phase, regulatory process and validation approach. This includes assessment of the test requirements and standards, preparation of sampling plans and written justifications for test methods selected, then working to help the client understand and interpret the test results once testing concludes. Not everyone works in a lab and it is important that the client understand how to properly interpret and use the test data they receive from their laboratory testing partner.
Socola: Initially we establish a relationship and gather as much information about the customer, their device and the reason they are seeking to have the validation work performed. For instance, is the customer looking for data to receive a CE mark in Europe, a 510(k) in the United States or just to add information to their products master device file? Each of these three scenarios could require that the device be tested very differently. Depending on the answer to this question, Highpower can begin to develop the tests that are required for the customer’s specific needs.
ODT: Can you provide an example of a testing challenge you faced with an OEM customer’s device, and how you met that challenge?
Wright: We recently completed a project for a client, which produces a device composed of thin layers of multiple polymer types. The thickness of each layer and the morphology of particles in each layer were of interest. A technique was developed that uses 18 different steps for staining, some with radioactive reagents. This allowed for transmission electron microscopy (TEM) images with individual material components within the device having distinct contrast. It was quite a challenge and therefore very satisfying when we were able to provide our client with exceptional TEM images and a testing solution that met their unique needs.
Jakucki: In the test lab, we break parts every day and we understand how the failure modes can help improve product designs. Our most common challenge is identifying design issues and then working alongside our clients to modify or even redesign. This can be costly and stretch out lead times but results in better device performance, which ultimately leads to better patient outcomes.
Small details such as sharp corners can quickly result in unexpected failures, and while the parts performed well in static evaluations, fatigue testing showed otherwise. We often recommend performing feasibility studies, which help evaluate devices prior to launching full testing studies. The last thing anyone wants to do is manufacture a large amount of product only to render it useless after the first couple of tests. We try to be aware of design and leverage our years of expertise to help identify potential design issues as soon as possible.
Socola: Yes, we have had many different situations over the years but one involving swine tendons was very challenging. We knew that the tendon would not be able to go through any high temperature sterilization process such as steam or dry heat, so that left us with low temperature sterilization processes. After performing a number of feasibility tests, we found sterilization with hydrogen peroxide vapor to hold the most promise and after further testing, was able to adjust the sterilization temperature, concentration level and exposure time in order to sterilize the tendon without altering or damaging it in any way.
ODT: How have orthopedic device testing methods changed over the past years?
Wright: There has been a great increase in the popularity of Restriction of Hazardous Substances (RoHS, often pronounced “row-hass”) testing. This could be attributed to the E.U. (European Union) RoHS Directive that mandated all medical devices and monitoring and control instruments must meet the established RoHS limits, which took effect July 22, 2014. We perform this analysis using X-Ray Fluorescence Spectroscopy. This technique uses a concentrated X-ray beam to provide an elemental analysis screening for heavy metals and other compounds on the RoHS lists.
Jakucki: Metal-on-metal hip implants have certainly sent a ripple through the testing world over the past several years. The increased scrutiny has resulted in a much larger focus on wear evaluation of modular connections and their associated fretting/corrosion and debris generation, across all implant platforms.
In addition, test methods are generally becoming more aggressive and complex in order to better address clinical failure modes. Specifically, there is an increased emphasis on multi-axial setups and environmental conditions.
Hansen: More quantitative assessments are required for regulatory approval, which can add time and expense to medical device manufacturers’ development projects. In addition, more clinically relevant implant sites are expected—extrapolation from other implant sites is no longer acceptable. Extractable/leachable (E/L) analysis is also increasingly expected, along with a toxicologic risk assessment of any chemicals found in the E/L analysis.
Rollins: For biocompatibility it has been a roller coaster of testing requirements. When I first came into the industry 13 years ago, most orthopedics just reused the same materials that were always used and performed limited testing. Issues with some materials and the introduction of novel materials caused a huge upswing in required testing. With the inclusion of material characterization and chemical characterization we have moved past a “check box” testing strategy to a scientific approach to biocompatibility testing.
Socola: We are seeing more requests for combination testing of reusable medical devices coming from the FDA. For example, in years past, an orthopedic device manufacturer could perform limits of reuse testing on their device (number of sterilization cycles it could withstand), along with an independent validation study on device cleaning and device efficacy. However, in 2015, the FDA is asking for the limits of reuse testing on the same device to include not only the device sterilization but also the device cleaning steps. After the limits of reuse testing has been completed, devices may then move on to other tests, such as cytotoxicity, biocompatibility or maybe even whole package integrity testing of an orthopedics set within a rigid container.
ODT: How does testing differ between different materials? What kind of testing challenges do implants and products made from different materials pose?
Wright: For failure analysis projects we are often analyzing modes of degradation. This involves examination of pitting or corrosion for metal products and oxidative discoloration and micro cracking for polymers. There are many test methods offered by Polymer Solutions that are applicable to any material type, but the techniques used for testing and analysis require background knowledge for each type.
Good sample preparation is often critical to standardized test methods. This is an area where working with different materials may require drastic changes in methodology. Polymer Solutions has a machine shop with typical power tools as well as specialty metallurgy equipment that allows us to work with just about anything. We occasionally work with samples that bridge material categories, such as an analysis of the solder joints embedded in an epoxy resin for a micro circuit board used in hearing aids. We had to prepare a cross-section of the whole device with a glassy smooth surface for microscopic analysis. Another example is a project we did for a client who produces a surgical device that has a metal housing with a polymeric anti-corrosion coating. A particular lot of devices were susceptible to flaking of the coating off of the metal after several autoclave cycles. Multiple techniques were used to analyze the metal, the coating, and their contact with one another to determine the reason for this defect.
Jakucki: Polymers are strain rate dependent and can generate different results based on the speed of the testing, both in static and fatigue methods. For ceramic testing, alignment is critical, as any misalignment can generate significant unintended bending stress, which can result in sudden bursting of the test specimen. Metal performance is generally well documented; however, metal interaction with other materials has been an area of particular interest over the last several years.
Different materials have different properties. This is especially important to understand when making devices that have various material couples. Using dissimilar materials can introduce additional risk which needs to be evaluated. A spine implant that has PEEK (polyether ether ketone) and titanium can have a much higher risk of generating wear debris as the materials make contact during testing. A hip implant that has a titanium stem and cobalt chrome neck will experience different types of corrosion due to the dissimilar metals. Two materials may be biocompatible, but that doesn’t necessarily mean that the resulting product or its generated debris will be safe.
Rollins: The preliminary material characterization we do before testing can have a significant impact on the testing plan. This is not so much dependent on the type of material but the history of use and established information on the materials. The more information we have the less testing that may be necessary. The biggest impact we see is from materials that are bio reactive.
Materials that are dynamic in vivo can have a complex biological response compared to traditional metal or hard plastic materials.
Alexa Tatarian: Different device materials hold on to residue differently and will behave differently in testing. Great consideration is taken when setting up a test plan to determine the most appropriate methods based on the device material. Very textured and porous materials create unique challenges from a testing standpoint. When textured and porous materials are present, we want to be aggressive in determining what can extract or leach from the device without breaking down the product. This can also be true for materials with unique coatings—these materials may interfere with the test methods and need to be addressed.
Socola: Good question. Different device materials do require different sterilization processes. For example, instruments made of stainless steel would typically be sterilized in a steam autoclave, while rubber, plastics and certain adhesives, would likely require sterilization efficacy testing in low temperature sterilization processes such as EO (ethylene oxide) gas or hydrogen peroxide. The sterilization efficacy testing may be different for various materials, the limits of reuse testing may be different and the biocompatibility testing most certainly would be different based on the device makeup. A few years ago, Highpower was involved with a revision of the Association for Advanced Medical Instrumentation TIR: 17—Compatibility of Materials Subject to Sterilization. This technical information report provides guidance for healthcare manufacturers in the selection and qualification of polymeric materials, ceramics, and metals in healthcare products that are sterilized by the various sterilization processes.
The most difficult devices are those that are being developed with no prior device testing to be used as a basis for the new device. In these situations, one may find it difficult to validate the device in a traditional type of sterilization cycle and may actually have to develop a sterilization cycle for the device.
ODT: Where do you see orthopedic device testing procedures going in the future?
Jakucki: Additive manufactured materials are making a significant impact in the medical industry. Many of our clients will manufacture their devices out of both a standard and additive material, and then test side by side to demonstrate equivalence.
Depending upon the quality of the process, we have seen a range of poor to superior performances. This is especially crucial when evaluating porous coating structures. Standard products such as thermal spray coatings have a proven performance, but 3-D printed coatings have had a mixed performance. Proper evaluation is the key to success. Requirements will include material validations in different printed orientations as well as product evaluation once materials issues have been resolved.
Hansen: Biologics is an exciting, rapidly growing product area that will affect orthopedics as well as a host of other indications. These new tissue-, cell-, or gene therapy-based products will likely require additional testing such as immunogenicity, tumorigenicity, and biodistribution analyses to support product safety. And, we expect to continue to see an expansion of combination products that will add even more complexity to the testing. Expertise in the execution and evaluation of these testing areas is an important future direction.
Rollins: Chemical characterization is becoming a large part of biocompatibility testing. Chemical characterization testing allows us to assess the impact of individual chemical compounds as opposed to relying on vague biological responses in animals.
Tatarian: 3-D printed devices have introduced obstacles from a testing perspective. There are different concerns and considerations for these devices than those produced using more traditional methods like wet or dry machining. Manufacturers are constantly trying to streamline their processes to limit the introduction of unnecessary contaminants. Testing procedures are evolving to use advanced analytical instrumentation to help identify and pinpoint specific residuals of concern. Relying on analytical instrumentation provides greater specificity in the test results for improved data interpretation, which ultimately helps ensure greater patient safety.
Socola: There are always new materials emerging in the development of new medical devices, and these materials like the others before them will require the standard types of testing. Limits of reuse, biocompatibility, sterilization efficacy, cleaning, residual testing and the like, will all still need to be performed but as stated earlier, some tests may no longer be allowed to be run individually on new devices by regulatory bodies like the FDA, but instead in combination testing to include the process of cleaning, packaging and sterilization or disinfection, to see if there are any cumulative effects on these new materials.
The key, experts in testing note, is that an off-the-shelf approach to testing does not work for orthopedic devices. Technology is advancing so rapidly that testing must be approached on an individual basis customer to customer. As much as products that appear to be the same—such as screws or plate systems—differ, so do customers. John Bolinder notes that Nelson Laboratories Inc. “looks beyond the test” to meet unique challenges from each customer, as well as regulatory requirements, head on and effectively.
Orthopedic Design & Technology’s expert sources came together to form a cohesive picture of how orthopedic device testing service providers are adapting to fast-changing landscapes; how they deal with new OEM (original equipment manufacturer) demands; and how they see testing services progressing and changing in the future. For instance, additive manufacturing is having an impact on how the companies approach testing. Experimentation with newer, perhaps cheaper materials in 3-D printing are posing challenges such as how to deal with more porous coatings. Also, those in the field of biologics will find an expanding job market as orthopedic devices using tissue, cell or gene-based therapies become more prominent. Testing such devices requires a specific skill and education set. In this vein, combination products—those that integrate hardware and pharmaceuticals—are on the rise, and will require experts in these crossover fields to test them adequately.
Experts at the roundtable include:
Jarret Wright, thermal, physical, and microscopy lab manager for Polymer Solutions Incorporated, a Christiansburg, Va.-based materials analysis and testing lab. The most common orthopedic products the company tests are bioabsorbable devices such as screws, tacks, pins, rods and plates. Wright notes that the chemical and physical properties of these products are heavily regulated because they perform as a medical device as well a as a drug.
Maciej Jakucki, department manager of medical device testing for Element Materials Technology in Cincinnati, Ohio.
Headquartered in London, United Kingdom, Element's team of over 1,800 "engaged experts" provide materials testing, product qualification, and failure analysis services in 51 laboratories throughout the United States and Europe. In the orthopedic space, Element performs mechanical testing for feasibility studies and regulatory submission purposes. Its most commonly tested devices include hip, knee, spine, and shoulder implants along with a wide variety of trauma, maxillofacial and dental devices.
Linda K. Hansen, Ph.D., scientific director of custom studies at WuXi AppTec. The company’s U.S. headquarters are located in St. Paul, Minn., with additional U.S. testing facilities in Atlanta, Ga., and Philadelphia, Pa. WuXi AppTec offers several areas of testing and services in the orthopedic area, from standardized osteoinductivity tests to custom pre-clinical efficacy studies, as well as tissue-based orthopedic product manufacturing.
John Bolinder, Alexa Tatarian and Thor Rollins, vice president of marketing and communications, study director in the chemistry department, and biocompatibility specialist and consulting manager, respectively, for Salt Lake City, Utah-based Nelson Laboratories Inc. Nelson Laboratories provides biocompatibility, sterilization validation, reuse and cleaning validation services, among others, on a wide range of orthopedic device types including surgical kits and trays, total joint, hip and knee implants, and small-bone devices such as bone screws.
Gary Socola, president of Highpower Validation Testing & Lab Services Inc. The firm’s testing services focus mainly on reusable medical devices that require cleaning, packaging and sterilization between patients. The company is headquartered in Rochester, N.Y.
ODT: Do you have an overall company philosophy when it comes to testing?
Jarret Wright: Polymer Solutions has an overall philosophy of quality and integrity. As a third-party testing lab our customers depend on precise and accurate results every time. We have a substantial amount of training and quality assurance procedures to ensure that we are able to deliver exactly that. There is also a philosophy that happy scientists do good science. Every Friday we have a company breakfast, and each month there are company events that foster fun and friendly interactions. We recognize that our work is a blend of strict scientific rigor but also creative thinking to tackle our clients’ most difficult materials challenges.
Maciej Jakucki: Element’s mission is to become the world’s most trusted testing partner. To achieve this, our testing philosophy is to be more than just a vendor to our clients. By providing pre-project consulting and review, we ensure that all interested parties are on the same page with the goals and objectives of each project. After testing, we provide comprehensive test reports and make ourselves available for discussion of results. This collaborative process leads to timely, accurate results that our customers can trust.
Linda Hansen: We aim to serve the client along the full path of product development from conception to pre-clinical regulatory approval. We believe in developing the best test plans to meet our customers’ specific needs, we take time to really understand those needs and develop our test plan accordingly. We don’t believe in a one-size fits all—we customize our approach.
Thor Rollins: We always consider what’s best for each client; devices which appear to be the same may have very different testing routes depending on the customer. Large medical device companies may benefit more from a reduced timeline where a small startup might be looking at the most cost effective solutions available. We make it a point to understand the client’s primary pain points so we can provide the most creative testing solutions for their unique needs.
Gary Socola: Yes, we take the business of medical device validations very seriously. We like to think of ourselves as an extension of our customers’ companies. There are plenty of laboratories that have a tremendous number of tests available that they can perform on a single-use or reusable medical device. We are not one of those laboratories. We want to be considered experts at what we do and we have found that our customers prefer to have a laboratory that they consider to be experts in reusable medical device packaging, cleaning and sterilization efficacy testing.
Because we specialize in cleaning, packaging and sterilization efficacy validation testing, we are extremely in tune with what is required from each part of the world and more importantly what changes are occurring right now at the U.S. Food and Drug Administration’s (FDA’s) Office of Device Evaluation.
ODT: What is your approach when starting work with a new customer?
Wright: It is very important for us to have a clear understanding of the problem or other need for testing. It is also important for the client to have a clear understanding of what results the analyses will provide. This two-way communication allows us to work together toward the solution. We clarify and work collaboratively with our clients to ensure success. Each client has a project manager who is their direct point of contact and serves as a liaison between them and our labs. Since we offer so many testing capabilities under one roof we find one technical point of contact ensures that start to finish, our entire team remains on the same page and exceeds our clients’ expectations.
Jakucki: We will spend time up-front with our new customers, taking the initiative to explain our process and the deliverables they can expect. In addition, we take the time to fully understand our client’s goals and ideas in order to help identify potential issues and share our expertise. New clients are often looking to learn as much as they can about test methods and new developments.
Our participation in ASTM (American Society for Testing and Materials) allows Element to be at the forefront of method development and, as such, direct our clients through successful testing projects.
Hansen: It is our goal to build strong relationships, partnerships with our customers. That starts by listening to fully understand the unique product or challenge that our customer is facing. We believe in transparency and accomplish that by establishing a key point of contact for customer interface which allows for efficient and effective communication of key details. Our technical staff is available to offer support, troubleshoot along the way and ensure the testing meets our customers’ goals.
John Bolinder: Ideally we take time to understand the product life cycle, consulting with the client to understand where they are in their product development phase, regulatory process and validation approach. This includes assessment of the test requirements and standards, preparation of sampling plans and written justifications for test methods selected, then working to help the client understand and interpret the test results once testing concludes. Not everyone works in a lab and it is important that the client understand how to properly interpret and use the test data they receive from their laboratory testing partner.
Socola: Initially we establish a relationship and gather as much information about the customer, their device and the reason they are seeking to have the validation work performed. For instance, is the customer looking for data to receive a CE mark in Europe, a 510(k) in the United States or just to add information to their products master device file? Each of these three scenarios could require that the device be tested very differently. Depending on the answer to this question, Highpower can begin to develop the tests that are required for the customer’s specific needs.
ODT: Can you provide an example of a testing challenge you faced with an OEM customer’s device, and how you met that challenge?
Wright: We recently completed a project for a client, which produces a device composed of thin layers of multiple polymer types. The thickness of each layer and the morphology of particles in each layer were of interest. A technique was developed that uses 18 different steps for staining, some with radioactive reagents. This allowed for transmission electron microscopy (TEM) images with individual material components within the device having distinct contrast. It was quite a challenge and therefore very satisfying when we were able to provide our client with exceptional TEM images and a testing solution that met their unique needs.
Jakucki: In the test lab, we break parts every day and we understand how the failure modes can help improve product designs. Our most common challenge is identifying design issues and then working alongside our clients to modify or even redesign. This can be costly and stretch out lead times but results in better device performance, which ultimately leads to better patient outcomes.
Small details such as sharp corners can quickly result in unexpected failures, and while the parts performed well in static evaluations, fatigue testing showed otherwise. We often recommend performing feasibility studies, which help evaluate devices prior to launching full testing studies. The last thing anyone wants to do is manufacture a large amount of product only to render it useless after the first couple of tests. We try to be aware of design and leverage our years of expertise to help identify potential design issues as soon as possible.
Socola: Yes, we have had many different situations over the years but one involving swine tendons was very challenging. We knew that the tendon would not be able to go through any high temperature sterilization process such as steam or dry heat, so that left us with low temperature sterilization processes. After performing a number of feasibility tests, we found sterilization with hydrogen peroxide vapor to hold the most promise and after further testing, was able to adjust the sterilization temperature, concentration level and exposure time in order to sterilize the tendon without altering or damaging it in any way.
ODT: How have orthopedic device testing methods changed over the past years?
Wright: There has been a great increase in the popularity of Restriction of Hazardous Substances (RoHS, often pronounced “row-hass”) testing. This could be attributed to the E.U. (European Union) RoHS Directive that mandated all medical devices and monitoring and control instruments must meet the established RoHS limits, which took effect July 22, 2014. We perform this analysis using X-Ray Fluorescence Spectroscopy. This technique uses a concentrated X-ray beam to provide an elemental analysis screening for heavy metals and other compounds on the RoHS lists.
Jakucki: Metal-on-metal hip implants have certainly sent a ripple through the testing world over the past several years. The increased scrutiny has resulted in a much larger focus on wear evaluation of modular connections and their associated fretting/corrosion and debris generation, across all implant platforms.
In addition, test methods are generally becoming more aggressive and complex in order to better address clinical failure modes. Specifically, there is an increased emphasis on multi-axial setups and environmental conditions.
Hansen: More quantitative assessments are required for regulatory approval, which can add time and expense to medical device manufacturers’ development projects. In addition, more clinically relevant implant sites are expected—extrapolation from other implant sites is no longer acceptable. Extractable/leachable (E/L) analysis is also increasingly expected, along with a toxicologic risk assessment of any chemicals found in the E/L analysis.
Rollins: For biocompatibility it has been a roller coaster of testing requirements. When I first came into the industry 13 years ago, most orthopedics just reused the same materials that were always used and performed limited testing. Issues with some materials and the introduction of novel materials caused a huge upswing in required testing. With the inclusion of material characterization and chemical characterization we have moved past a “check box” testing strategy to a scientific approach to biocompatibility testing.
Socola: We are seeing more requests for combination testing of reusable medical devices coming from the FDA. For example, in years past, an orthopedic device manufacturer could perform limits of reuse testing on their device (number of sterilization cycles it could withstand), along with an independent validation study on device cleaning and device efficacy. However, in 2015, the FDA is asking for the limits of reuse testing on the same device to include not only the device sterilization but also the device cleaning steps. After the limits of reuse testing has been completed, devices may then move on to other tests, such as cytotoxicity, biocompatibility or maybe even whole package integrity testing of an orthopedics set within a rigid container.
ODT: How does testing differ between different materials? What kind of testing challenges do implants and products made from different materials pose?
Wright: For failure analysis projects we are often analyzing modes of degradation. This involves examination of pitting or corrosion for metal products and oxidative discoloration and micro cracking for polymers. There are many test methods offered by Polymer Solutions that are applicable to any material type, but the techniques used for testing and analysis require background knowledge for each type.
Good sample preparation is often critical to standardized test methods. This is an area where working with different materials may require drastic changes in methodology. Polymer Solutions has a machine shop with typical power tools as well as specialty metallurgy equipment that allows us to work with just about anything. We occasionally work with samples that bridge material categories, such as an analysis of the solder joints embedded in an epoxy resin for a micro circuit board used in hearing aids. We had to prepare a cross-section of the whole device with a glassy smooth surface for microscopic analysis. Another example is a project we did for a client who produces a surgical device that has a metal housing with a polymeric anti-corrosion coating. A particular lot of devices were susceptible to flaking of the coating off of the metal after several autoclave cycles. Multiple techniques were used to analyze the metal, the coating, and their contact with one another to determine the reason for this defect.
Jakucki: Polymers are strain rate dependent and can generate different results based on the speed of the testing, both in static and fatigue methods. For ceramic testing, alignment is critical, as any misalignment can generate significant unintended bending stress, which can result in sudden bursting of the test specimen. Metal performance is generally well documented; however, metal interaction with other materials has been an area of particular interest over the last several years.
Different materials have different properties. This is especially important to understand when making devices that have various material couples. Using dissimilar materials can introduce additional risk which needs to be evaluated. A spine implant that has PEEK (polyether ether ketone) and titanium can have a much higher risk of generating wear debris as the materials make contact during testing. A hip implant that has a titanium stem and cobalt chrome neck will experience different types of corrosion due to the dissimilar metals. Two materials may be biocompatible, but that doesn’t necessarily mean that the resulting product or its generated debris will be safe.
Rollins: The preliminary material characterization we do before testing can have a significant impact on the testing plan. This is not so much dependent on the type of material but the history of use and established information on the materials. The more information we have the less testing that may be necessary. The biggest impact we see is from materials that are bio reactive.
Materials that are dynamic in vivo can have a complex biological response compared to traditional metal or hard plastic materials.
Alexa Tatarian: Different device materials hold on to residue differently and will behave differently in testing. Great consideration is taken when setting up a test plan to determine the most appropriate methods based on the device material. Very textured and porous materials create unique challenges from a testing standpoint. When textured and porous materials are present, we want to be aggressive in determining what can extract or leach from the device without breaking down the product. This can also be true for materials with unique coatings—these materials may interfere with the test methods and need to be addressed.
Socola: Good question. Different device materials do require different sterilization processes. For example, instruments made of stainless steel would typically be sterilized in a steam autoclave, while rubber, plastics and certain adhesives, would likely require sterilization efficacy testing in low temperature sterilization processes such as EO (ethylene oxide) gas or hydrogen peroxide. The sterilization efficacy testing may be different for various materials, the limits of reuse testing may be different and the biocompatibility testing most certainly would be different based on the device makeup. A few years ago, Highpower was involved with a revision of the Association for Advanced Medical Instrumentation TIR: 17—Compatibility of Materials Subject to Sterilization. This technical information report provides guidance for healthcare manufacturers in the selection and qualification of polymeric materials, ceramics, and metals in healthcare products that are sterilized by the various sterilization processes.
The most difficult devices are those that are being developed with no prior device testing to be used as a basis for the new device. In these situations, one may find it difficult to validate the device in a traditional type of sterilization cycle and may actually have to develop a sterilization cycle for the device.
ODT: Where do you see orthopedic device testing procedures going in the future?
Jakucki: Additive manufactured materials are making a significant impact in the medical industry. Many of our clients will manufacture their devices out of both a standard and additive material, and then test side by side to demonstrate equivalence.
Depending upon the quality of the process, we have seen a range of poor to superior performances. This is especially crucial when evaluating porous coating structures. Standard products such as thermal spray coatings have a proven performance, but 3-D printed coatings have had a mixed performance. Proper evaluation is the key to success. Requirements will include material validations in different printed orientations as well as product evaluation once materials issues have been resolved.
Hansen: Biologics is an exciting, rapidly growing product area that will affect orthopedics as well as a host of other indications. These new tissue-, cell-, or gene therapy-based products will likely require additional testing such as immunogenicity, tumorigenicity, and biodistribution analyses to support product safety. And, we expect to continue to see an expansion of combination products that will add even more complexity to the testing. Expertise in the execution and evaluation of these testing areas is an important future direction.
Rollins: Chemical characterization is becoming a large part of biocompatibility testing. Chemical characterization testing allows us to assess the impact of individual chemical compounds as opposed to relying on vague biological responses in animals.
Tatarian: 3-D printed devices have introduced obstacles from a testing perspective. There are different concerns and considerations for these devices than those produced using more traditional methods like wet or dry machining. Manufacturers are constantly trying to streamline their processes to limit the introduction of unnecessary contaminants. Testing procedures are evolving to use advanced analytical instrumentation to help identify and pinpoint specific residuals of concern. Relying on analytical instrumentation provides greater specificity in the test results for improved data interpretation, which ultimately helps ensure greater patient safety.
Socola: There are always new materials emerging in the development of new medical devices, and these materials like the others before them will require the standard types of testing. Limits of reuse, biocompatibility, sterilization efficacy, cleaning, residual testing and the like, will all still need to be performed but as stated earlier, some tests may no longer be allowed to be run individually on new devices by regulatory bodies like the FDA, but instead in combination testing to include the process of cleaning, packaging and sterilization or disinfection, to see if there are any cumulative effects on these new materials.