Furthering Orthopedic Implant Fabrication Methods

Orthopedic implant manufacturing continues to expand as an industry at a steady (but not spectacular) pace. The value of the orthopedic implants market is projected to exceed $78 billion by 2033—a compound annual growth rate of 4.9% from 2024 to 2033. Factors driving this growth include advances in additive manufacturing technologies, automation, digital Internet of Things (IoT) applications, and an aging population that requires orthopedic implants to remain fit and active.

Much of this innovation is happening in the spinal market.

“The complexity of implants in the spinal arena is expanding and that is largely due to advancements in precision machining methods and metrology,” said Kelly Cimillo, senior account executive for Triangle Manufacturing Company, an Upper Saddle River, N.J.-based contract manufacturer of precision-machined orthopedic implants and instrumentation. “New high-tech and high-speed equipment, along with a more profound use of wire EDM [electrical discharge machining], are allowing implant manufacturers to produce complex geometry holding tighter tolerances.”

Mark Barker, program manager for Vaupell, an Everett, Wash.-based full-service contract manufacturer that serves the medical, defense, and aerospace industries, agreed.

“In addition to the need for smaller finished forms and new surgical instruments for implanting those forms, there is growing demand for more complex designs and advanced manufacturing to create custom, patient-specific, fitted solutions,” said Barker. “These factors have contributed to advancements in new materials and a closer examination of their overall performance.”

Popular materials include ultra-high molecular weight polyethylene (UHMWPE) for joint replacement implants and polyether ether ketone (PEEK) and carbon fiber-reinforced PEEK implants for spine surgeries. “A clear trend that can be observed in UHMWPE implant manufacturing is the transition to cross-linked and vitamin E-blended materials,” said Patrick Fässler, CEO for Gsell, the U.S. subsidiary of Gsell Medical Plastics AG, a Switzerland-based strategic supplier of medical polymer implants, carbon fiber, and custom single-use instruments.

These and other advanced materials are being used more frequently in trauma implant production, driven by various properties such as enhanced corrosion resistance, nickel-free stainless steel, biocompatibility, and increased strength requirements. “This trend has led to the creation of several new stainless steel alloys,” said Barker.

Supply chain delays are still causing headaches for ortho companies regarding supplies and materials, which slow down implant production, speed to market, and R&D for product development.

“Material availability continues to be a hot topic in supply chain organizations,” said Shawn Schafer, vice president of business operations for Oberg Medical, a Sarver, Pa.-based full-service medical device contract manufacturer that provides implants, instruments, and stamped metal components. “Compounding the issue is overall lead time which, in some cases, can extend beyond 60 to 90 weeks. This requires our customers to provide better forecasts and/or purchase order coverage to mitigate risks on delivery.”

Current Trends

Orthopedic manufacturers are utilizing a greater variety of coating methods and surface texturing on implants, which aim to improve overall performance and reduce wear caused by friction. “Some of these advancements include nanostructured coatings, bioactive coatings, surface texturing, drug-eluting coatings, antimicrobial coatings, and smart coatings,” said Barker.

Because of their unique capabilities, lasers are being used more frequently in orthopedic implant production. Ultra-fast lasers are in high demand because of their speed and precision—for example, they can cut features as small as 0.0005 inches (13 microns) with high accuracy and no thermal damage. With an average pulse width of 150 femtoseconds (150 quadrillionths of 1 second), there is virtually no heat transfer beyond the dimensions of the cut, making it a “cool” process. Applications include creating intricate, microtextured patterns or lattice structures on part surfaces, drilling high-precision holes, and micro-texturing patterns or grooves into the sides of molds or onto implant surfaces.

“Surface texture plays an important role in the osseointegration of metal orthopedic implants,” said Blake Winkelmann, technical solutions manager for Spectrum Plastics Group, a DuPont Business that provides development through scaled manufacturing of critical polymer-based components and devices for medical and other demanding markets. “Femtosecond lasers are often used to create fine texture patterning on implantable hardware. Laser texturing allows for precise control of depth, size, and location of the applied texture in a cleaner process than other more traditional methods.”

As implants become smaller and more complex, significantly more inspection requirements are being added to the deliverables required by the medical device manufacturer’s (MDM) process for introducing new products to the market. Although implant designs have not changed greatly in recent years, ortho companies have changed the way the features are dimensioned and modeled, requiring more coordinate measuring machine (CMM) and/or non-contact inspection.

“Product designs are also becoming more stringent dimensionally,” John Helmuth, general manager at Wilmington, Mass.-based Tecomet, which develops full-spectrum, scalable manufacturing solutions for medical device companies, said in an ODT roundtable discussion last year. “The traditional methodology for producing parts is manual gaging methods and basic profile verification, whereas the new designs use coordinate measuring machines [CMM] and optical scanning methods. There are tighter tolerances that come with all that and more precision is required for those tighter tolerances.”

“Companies continue to move away from ‘hard gaging’ in favor of slower and more costly CMM inspection,” agreed Schafer. “Oberg has added 12 CMMs over the past few years to address the geometric dimensioning and tolerancing being added to customer designs and drawings.”

CT scanning in the additive manufacturing space has been an invaluable tool when developing new products that push innovative concepts. This inspection method can scan a titanium implant in less than an hour with a resolution of approximately 10 microns. “This has been critical in low-volume products such as patient-specific projects, where every part might be completely unique,” said Sloan Volkman, additive manufacturing engineer for rms Company, a Coon Rapids, Minn.-based Cretex Medical company and contract manufacturer to the medical device industry. “Additionally, it is a great way to get dimensional data gathered and stored quickly without needing a CMM program. The ability to scan a part and section it in infinite angles, without having to do destructive testing, has also allowed us to find defects such as cracks, porosity, trapped powder, and dimensional non-conformance.”

Ultimately, “metrology correlation, early on, between the contract manufacturer and the orthopedic manufacturer, is essential for eliminating false rejects,” noted Bob Imhoff, senior account executive for Triangle Manufacturing Company.

What Ortho Companies Want

Top priorities vary among orthopedic implant manufacturers. For some, the main focus is the supply chain—how to deal with fluctuations in material shortages, prices, lead times, and availability of different stock shapes. Even with these supply chain impacts, MDMs still push their contract manufacturers (CMs) for year-over-year cost reductions—even as implants get more complicated and costly to make. “Overall, price and lead time are always key concerns for ortho companies,” said Fässler.

MDMs also look to shorten supply chains, which often means more vertical integration. In turn, this improves communication, decision-making, and speed to market. Ortho manufacturers are also pushing more process capabilities and quality management responsibilities onto their suppliers to reduce internal inspections and associated costs.

“In addition, ortho companies are looking for a simpler purchasing process that may include cleanroom, packaging, and labeling services,” added Fässler. “We have invested in additional cleaning equipment to offer a final cleaning and rinsing of implants and have re-validated the entire cleaning process, up to the latest regulatory and customer-specific requirements.”

Some OEMs bid out large packages, claiming they are reducing or consolidating their supply base. Most of the time, however, this is an attempt to reduce pricing. For example, the quote packages include all the part numbers across many different product lines to gather pricing from their preferred suppliers. “They explain that this exercise is a chance to gain new business, but really what they are doing is looking for the lowest pricing so they can go back to the incumbent supplier and ask for price reductions, stating if we cannot improve, they will re-allocate the business to the lower priced supplier—which they really do not want to do,” said Imhoff. “In reality, this benchmarking exercise is only used to leverage existing suppliers to reduce their margins.”

Technologies, Tools, and Know-How

Within the orthopedic implant industry, the spinal market has probably shown the greatest amount of innovation. Traditional machining of PEEK spine implants is steadily decreasing and 3D printing of titanium implants is spreading rapidly, driven more by improved patient outcomes than optimization in manufacturing processes. In the near future, 3D-printing of PEEK implants could also become a favored manufacturing approach.

“Implants must be manufactured in a highly controlled process that is very precise and repeatable,” said David Cabral, president and CEO of New Bedford, Mass.-based Five Star Companies, a full-capability contract manufacturer and surgical instrument repair/refurbishment company.

For most non-metal components, machining must be done without coolant or other contaminants. For example, due to the expansion/contraction coefficients of UHMWPE material, “we machine the components out of specification in the cold-air environment with dedicated machinery,” said Cabral. “Once the component is completed and removed from the machine, it will warm to room temperature and come into compliance with the required dimensions. It sounds strange, but this approach works and is based on our team’s extensive experiences with these materials.”

With the increased volume of total joint replacements comes the need to improve production processes for tibial trays. Large surfaces, tight tolerances, and fatigue performance standards have required CMs to adapt the way they heat-treat parts to manage warpage and improve mechanical properties. “Hot isostatic pressing [HIP] has historically been the heat treatment of choice across the additive scene, but these tibial designs require creative heat-treatment solutions outside of just HIP,” said Volkman. “Vacuum furnace treatments to relieve stress and/or anneal parts have been critical to complementing and replacing HIP to keep parts dimensionally accurate, while still modifying microstructure appropriately, opening the door to get creative with process flow and reduce scrap from defects.”

Almost all MDMs and their CMs are using automation and robotics in some measure to improve quality, efficiency, and speed of production, all while reducing operational costs. A goal for many manufacturers is to create robotic/automated cells that can run production equipment unattended for long periods of time and even measure, inspect, and mark parts in serial production, thereby eliminating process steps and reducing costs. “Automation of capable processes is the best way to improve upon legacy processes,” said Imhoff.

“This can be a robot loading and unloading a part or a multi-pallet system set up to run unattended.”

The ultimate set-up for speed and reduced production costs is “lights out” manufacturing, which is a production method where, through automation and robotics, it can operate with minimal or no human intervention. Achieving this level of “dark factory” performance requires the integration of IoT-based technologies with configurable machines and conveyor belts, vision systems, and advanced process control software. Lights-out manufacturing is not always easy to achieve—however, when it is successfully implemented, it reduces labor costs and maximizes production efficiency.

AM continues to expand design options for implant engineers. By de-constraining design specifications, AM allows them to design and build components and products that are impossible to make with standard manufacturing methods. Rapid AM advances such as print resolution improvements and larger selections of printable materials “have also made AM an appealing alternative to more common fixture-creation processes, not to mention that it allows for more rapid prototyping than ever before,” said Cody Bonk, sales engineer for Marquette, Mich.-based Able Medical Devices, which provides services ranging from product design and development to comprehensive finished goods manufacturing for the medical device industry.

However, like in most disruptive manufacturing technologies, there are still plenty of challenges when using AM and 3D printing. These include variability of fine build features, cleanliness, and the need for secondary processes that still require conventional methods of manufacturing. This often adds lead time and cost—however, on the positive side, meaningful advancements in cleaning technologies, conventional machining, advanced inspection, and product finishing help AM stay competitive with other manufacturing methods.

As additive technology becomes more common, engineers are looking at existing subtractive-manufactured parts and wondering how AM can improve the process. “Whether it’s combining additional post-processes, such as titanium plasma spraying or diffusion bonded meshes, the ability for additive technology to add porous lattices to any part—all in one step—has been gaining popularity,” said Volkman.

More implants are being designed to be patient-specific. This is accomplished by CT scanning the patient and then creating an implant that perfectly matches the patient’s existing anatomy. “These implants can be manufactured quickly and cost-effectively by designing a standardized base that uses off-the-shelf hardware, and then customizing the surfaces that interface with the patient,” said Volkman. “It is a great use case for additive manufacturing where digital customization from the surgeon’s preferences can be brought to fruition without modifying downstream CNC [computer numerical control] programs or adding manual processes.”

Moving Forward

One of the issues in the AM community is the lack of standardized evaluation techniques and terminology necessary to fully characterize the unique products that can be designed for and made with AM. “A good example would be the unique surface topology that can be obtained via AM,” said Ryan Kircher, principal additive manufacturing engineer for rms Company. “Standard surface roughness terms like Ra value are not descriptive enough for these types of surfaces, which can be critical in how a device performs in situations like dynamic loading. Reliance on old conventional test methods has led to an inability to fully define AM products on technical drawings, forcing manufacturers to conduct costly equipment and process validations, which inhibit innovation and supply chain flexibility. The FDA has recognized these limitations and is working with industry experts to develop and standardize newer test methods more applicable to the devices we are manufacturing.”

Legacy products and validation procedures and timelines keep many orthopedic manufacturers from investing in new innovative materials and products. Many of the “new” products they release are based on previous designs. If there are tightly toleranced features that are critical from the previous design, the product development team will rarely change them in the new product because of the validation/510(k) requirements that must be met when a key feature or characteristic is modified—which drives up costs and delays speed to market. “For released product designs, design for manufacturability and design for inspection are usually off the table, depending on the ROI to the OEM for the change,” said Cimillo. “In general, changes are not well received due to the time, testing, cost, and approvals required for the OEM.”

Technology is always the way of the future and advances are ongoing in the orthopedic implant industry. For example, sophisticated machine monitoring software, when used in conjunction with advanced artificial intelligence (AI), enables predictive maintenance to calculate failure patterns in components and tooling. AI-driven algorithms can generate supports that minimize printing time and material use while still supporting challenging geometries. AI also helps production engineers evaluate the immense amount of data that is generated during the AM process and identify any potential processing issues.

“Artificial intelligence is very helpful in multiple ways,” said Volkman. “For example, we use AI to help predict the best orientation and supports for printing with a laser powder bed fusion system. With simulation tools, we can get a good idea of the thermal stresses a part may see during printing. We can then use this information to select locations to support the part accordingly and ensure parts conform to required dimensions. AI-generated build simulations are a great way to avoid defects such as shrink lines, before even printing the first part.”

IoT can create “smart” implants with embedded sensors that can monitor kinematics and performance through the lifecycle of the implant and eventually provide intelligence on improving outcomes. This will likely become a hot market within the orthopedic implant industry in the next few years, especially with the assistance of AI.

“Smart implants—the in-molding of electronics into PEEK—are already being developed,” said Fässler. “More niche applications are also being developed for PEEK carbon fiber-reinforced implants—for example, trauma and spine—due to its advantages of radiolucency and mechanical properties.”

An increasing number of orthopedic implant manufacturers are adopting implant lifecycle management (ILM) strategies to track long-term patient outcomes and device performance. ILM involves management processes from conception, design, and manufacturing to sales and repairs. “Advances in ILM are mainly software-based and use unique device identification, automated invoice processing, or implant tracking,” said StartUs Insights, a business intelligence firm that tracks multiple high-tech industries. “It also ensures the safe disposal of toxic waste because of the precise tracking of used materials during manufacturing. Manufacturing companies use IML solutions to reduce costs and maintain compliance.”

ILM also intersects the growing commitment that ortho companies have toward their sustainability initiatives and goals, “including environmental, social, and governance [ESG] performance and efforts to minimize their environmental footprint, enhance workplace safety, and contribute positively to society,” said Barker.

MDMs also expect their CMs and other supply chain partners to develop similar sustainability programs. Not only are these practices important for the environment, but implant manufacturers also want their customers to be aware of their commitment to sustainable practices, which can be a differentiator in the marketplace.