Orthopedic Manufacturing: A Look at the Current State of Product Development

With multiple cost stressors on the orthopedic market—including the medical device tax—orthopedic OEMs are intent on saving time and money. This means adding value whenever they can to existing products to improve performance and make them stand out from the competition—usually by using methods and materials that already have regulatory approval and validated by a large body of testing and performance data. For many orthopedic manufacturers, the research-and-development mission has become enhancing existing products and getting them to market quickly, while still meeting or exceeding regulatory requirements and
keeping costs down.

Achieving these goals can be a challenge for the contract manufacturer and depends on a number of factors, including the type and size of the project and whether the contract manufacturer must be fully integrated into the customer’s quality and design system. Understanding user needs early in the design process also is essential for speeding up product development—especially through the efficient use of rapid prototyping. By manufacturing prototypes quickly and inexpensively via additive manufacturing methods, engineers can hold, examine, and test these products very early in the design process. This makes it much easier to identify flaws and inconsistencies, which can then be “designed out” and retested with a minimum number of iterations.

Top R&D Trends
Orthopedic engineers continue to improve advanced-bearing surfaces in implants with the goal of reducing wear debris and implant loosening, as well as extending implant longevity. This includes testing engineered plastics for articulating devices like hips and knees, including biological reaction to wear debris. Research continues in cross-linked polyethylene and vitamin E cross-linked polyethylene. Although vitamin E-cross-linked polyethylene laboratory in-vitro testing has shown positive results for controlling oxidation, longer term follow-up testing is required to prove the clinical benefits of vitamin E materials. 

Polyether ether ketone (PEEK), which has proven itself in the spinal market for many years, is strong, biocompatible, radiolucent, and easily adaptable for machining and molding. As a bearing surface, however, PEEK is sup-optimal in high load-bearing applications (such as hip and knee implants) unless additives such as carbon fiber are used to increase strength. Although some companies market carbon-fiber-reinforced PEEK materials as acceptable wear surfaces for acetabular liners, most device manufacturers avoid PEEK for these applications while they wait for more clinical data confirming its reliability as a high load-bearing surface. 

The U.S. Food and Drug Administration (FDA) is placing increased scrutiny on new materials—especially for bearing couples—and is asking more questions related to the wear performance of these materials. Standard cross-linked polyethylene, vitamin-E cross-linked polyethylene, carbon fiber PEEK, and titanium carbide all are new materials that require additional tests such as third-body wear testing, particulate analysis, particle counts, morphology, and leaching studies (traditional polyethylene bearing surfaces do not require these tests). Also, since many of these types of tests are relatively new, there are no ASTM or ISO standards that specify how to run these tests, which can be a challenge when trying to find a predicate device/test for comparing results—which can drive up costs. Therefore, considerable R&D is being directed toward justifying these new testing parameters, acceptance criteria, worst-case samples, appropriate loading regimes, etc., to provide data that is acceptable to the FDA.

Design for Manufacturability
More complexity means more cost. OEMs are looking for ways to reduce costs through simpler design strategies—for example, assembly simplification. Finding ways to maintain or improve functionality by using designs that have fewer pieces and/or less complex modes of operation are significant breakthroughs that can reduce overall production costs. For example, using casting, additive manufacturing, or metal injection molding to join multiple parts in an assembly into one part that would otherwise be too complicated to machine as a single piece reduces the number of parts and eliminates some assembly steps. Engineers also are always looking for ways to optimize production—machine programs, operation order, process type, and other elements can be experimented within the prototype environment to achieve a process that easily can be transferred into a production environment.

Rapid Additive Manufacturing
Design for manufacturability studies can greatly benefit from rapid additive manufacturing (AM) technologies for making prototypes. Rapid additive manufacturing eliminates the time-consuming steps and delays that come with standard prototyping. What used to take weeks or months can now be done in a few hours, saving time and materials and driving down costs. Popular additive manufacturing technologies are direct metal laser sintering and 3-D printing in plastics. Both of these processes have revolutionized the way engineers approach the concept and design stages. Within hours, parts can be manufactured, held, and closely examined, making it much easier to identify errors and flaws, and design them out of the process.

Occasionally, additive manufacturing methods can be used to create production-ready metal parts from steel and titanium, which saves considerable time and money. Difficult geometries easily can be achieved using AM. Porous coatings also can potentially be printed directly on the part. Making fully functional parts with AM methods, however, currently is only practical for low-volume runs because of the post-processing that is required. For example, gross geometries easily are accomplished with AM but tight tolerances often cannot be reliably held—as a result, some post-process machining often is required for features like locking mechanisms, articulating surfaces, and assembly features requiring extremely tight fits. Some companies use AM technologies to mass-produce parts that are simple in design and require minimal post-build machining because the process has been optimized and validated. Overall, however, high-volume AM production still is cost-prohibitive. Current research is targeting process improvements and cost-reduction strategies.

Sterile Packaging and Product Delivery Systems
More complex products also create more packaging and sterilization challenges. The FDA also is becoming more concerned about sterilization requirements, especially in light of recent patient deaths associated with serious illnesses transmitted via imperfectly sterilized instruments.

As a result of these concerns (as well as another way to reduce costs), more companies and healthcare end users are using disposable instruments with pre-packed “peel and dispose” types of packaging, instead of more expensive instruments that are sterilized and reused. Packaging design and materials rapidly are evolving to better withstand transportation, temperature variations, and other factors to deliver a longer shelf life. Customized packaging is needed for these applications, which can be expensive for low-volume types of parts. Also, many products that were once non-sterile are now being sold as sterile, requiring new and validated packaging options for sterilization processes such as ethylene oxide radiation, vaporized hydrogen peroxide, and plasma.

Forming Strong Relationships
The best solution for maximizing product quality, improving time to market, and reducing overall cost is building long-term relationships with highly qualified suppliers and inviting them to share their knowledge and expertise during product development. Their knowledge of what works and what doesn’t is gained from working on hundreds of different projects with different designs, materials, processes and technologies—this tribal knowledge is vital to developing a smooth-running and cost-efficient design and
production process.

Working with the customer in the concept and/or design stages enables the contract manufacturer (CM) to develop the best possible design and production process to meet or exceed customer requirements in a timely and cost-efficient manner. Human factors engineering especially is important to do early on and is greatly enhanced by rapid prototyping and 3-D printing. Getting the designs off the computer screen and into people’s hands is critical for initiating thoughtful dialogue about how the products can be improved—especially how they are held and used in the working environment. These improvements are best identified and tested through several rounds of rapid prototyping.

Depending on the size of the project, getting the contract manufacturer involved in the concept stage can save up to one-third of total production cost. This also includes the CM’s help in determining the best way to invest funds during the R&D phase of the project. When properly targeted, R&D dollars can provide a significant return on investment during the design, production, and packaging stages.

When looking for a contract manufacturing partner, evaluate how the CM will assist you through the entire process, from conception to production and delivery. Contract manufacturers should be eager to be fully engaged in the concept and development stages and bring considerable medical device experience to the table. On-site prototype capabilities are critical for enabling engineers and fabricators to have daily interaction regarding things that are learned during prototype manufacturing, so changes made to the design and key aspects of what makes the prototype work are properly documented. It also is important that the CM uses the same computer-aided design software as the customer so that all files are compatible, streamlining the exchange process.  

Cost goals typically drive every medical device project and are best attained when the CM and the customer collaborate. It’s hard for OEM engineers and design teams to keep up with the latest in advanced materials, improved prototyping and injection molding technologies, additive manufacturing and 3-D printing capabilities, and sterilization and product delivery systems—all of which are evolving very quickly. The experts who do have this up-to-date knowledge, however, are CMs and other vendors who work with a variety of clients and project types across the medical device industry. By teaming up with CMs during the concept and design stages to allow them to share their industry-wide knowledge and experience, OEMs improve their odds of developing a better product that meets or exceeds their initial expectations, at a lower cost. 

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Ron Litke and Chris Scifert, Ph.D., are engineering managers with Holt, Mich.-based Orchid Orthopedic Solutions Inc.
Scifert has more than 12 years of experience including serving as senior manager of product development at Medtronic Spinal and Biologics, where he executed engineering projects and group management responsibilities for intradiscal and extradiscal dynamic stabilization systems and semi-rigid tumor/trauma technologies. Scifert is a certified Lean Sigma green belt and supported the continuing improvement efforts during his tenure at Medtronic. Scifert’s additional experience includes managing engineering projects as a senior engineer and project manager at Smith & Nephew, focusing on early intervention knee and shoulder systems. Scifert received his bachelor’s degree in engineering sciences and mechanics at the University of Tennessee and his Ph.D. in biomedical engineering at the University of Iowa with his doctoral dissertation titled, “A Finite Element Investigation into the Biomechanics of Total Artificial Hip Dislocation.” Scifert is based at Orchid’s facility in Memphis, Tenn.

Litke’s expertise is in the design and development of mechanical systems and mechanisms. He has strong computer-aided engineering experience coupled with solid manufacturing process expertise including welding, forging, extrusion, casting and machining. He also is certified through the American Society of Mechanical Engineers as a Senior Level GD&T (geometric dimensioning and tolerancing) Professional. He was employed by Cannondale and NextRnd, a contract engineering firm. Litke has 15 years of engineering experience, and received his bachelor’s and master’s degrees in mechanical engineering from the University of Connecticut. He holds 11 patents or patent applications. Litke is based at Orchid’s facility in Shelton, Conn.