New Approaches, Better Products
Innovation in product research and development comes in a number of different forms and disciplines.
Patient and physician expectations regarding joint replacement performance have increased over the years. Baby boomers especially have led the drive for developing implant systems that are more comfortable and provide increased range of motion, incorporating longer-lasting materials that will meet the needs of more active patients. For OEMs and their supply chains, this requires more challenging design and engineering work, the latest materials and technologies and in-depth, post-market surveillance.
Working directly with surgeons—in risk assessment, creative work and design verification, among others—is a critical component in the R&D process. Pictured above is an offset reamer handle designed to allow easier access to the hip. Photo courtesy of Greatbatch Medical.
“As the indications for joint replacement have broadened, we have seen increased demand for more tailored or personalizedsolutions, such as knee implants designed specifically to fit the anatomy of women,” said Garry Clark, director of public relations for Zimmer, a Warsaw, Ind.-based developer of orthopedic reconstructive, spinal and trauma device-related surgical products. “Other examples would be Zimmer’s Continuum acetabular cup system that allows surgeons to choose between metal, polyethylene or ceramic bearing materials to best match the demands of each patient’s lifestyle. New technologies for hip stems feature a range of modular neck options that enable independent, intra-operative control of leg length, offset and version for a more accurate restoration of the patient’s natural anatomy.”
During the last several years, patient-specific instrumentation and other intelligent instruments designed to personalize the surgical experience have become more widespread. These are designed to ensure accurate placement of the knee implant for an optimal fit, feel and function.
“They also help streamline surgicalprocedures by eliminating numerous steps in the conventional knee replacement process, potentially reducing surgery time and increasing operating room efficiency,” added Clark.
Another noticeable trend in orthopedic product research and development is the move toward minimally invasive devices with smaller profiles that are more complex and functional. These enable the surgeon to complete the procedure through a smaller incision, usually in less time and with greater repeatability and accuracy, resulting in better outcomes and shorter hospital stays.
“There have been many adaptations to surgical approaches for a number ofprocedures for joints, spine and trauma that have driven requirements for different instrumentation,” said Hugh Davies, director of orthopedic product line management and marketing for Greatbatch Medical in Clarence, N.Y., which designs, develops and manufactures a variety oforthopedic products. “New instrument
designs to enable a new surgical approach or a smaller incision are a commondemand for most of the projects that we have been doing over the past several years. For example, our total hip arthroplasty (THA) product offerings have consistently evolved to support minimally invasive surgical techniques.”
The demand for smaller, faster and more functional orthopedic devices can challenge the limits of implant design and production. Systems must be installed or adapted to handle advanced materials, increased design complexity, and even tighter machined tolerances—all while maintaining or improving quality and time to market.
For Secant Medical LLC, a Perkasie, Pa.-based manufacturer of high-performance woven, knitted and braided fabrics for implantable devices, the goal is to create the smallest yet strongest textile possible. Secant Medical uses a variety of metallic and polymeric biomaterials to engineer textile components for high-strength sutures, bone anchoring devices, rotator cuff and arthroscopic joint repair, spinal stabilization, textile-based heart valves and vascular grafts, and lightweight textile mesh structures for tissue reinforcement and wound support.
The trend toward miniaturization,however, often results in unique challenges for biomedical textiles.
“The fibers lose strength as theybecome smaller so the same textile-forming techniques of the past will not work going forward,” said Amy Woltman, program engineer for Secant Medical. “It is more challenging to intertwine these fiber elements due to the significant amount of intimate contact between the fibers and the machine technology we utilize to form them. The resulting effect is an increased challenge in maintaining the high level of quality our clients expect. We recognize the impact that miniaturization has on our technology resources and we continue to invest heavily back into our company in order to meet the market demand.”
Medical device suppliers often maintain their own contacts within the surgeon community to evaluate product both in the office and cadaver labs.
“Our team has many years of experience in orthopedics, much of it working with surgeons. That experience is constantly in use in risk assessment, creative work and design verification,” said Davies.
“In one team of six people we can easily show over 100 years of combined industry experience. On several projects we have met with the surgeons specified by the OEM, collected design requirements and then continued to interface with the surgeons through prototyping and device evaluation until completing a full product line, meeting the users’ need.”
OEMs and their manufacturing partners that deliver the best possible prototypes as early as possible in the production schedule can help improve decision-making times and schedules, lower costs and increase efficiencies. OEMs, in turn, then benefit from a reduced need for assembly and development, and possibly fewer additional materials as well, which also saves money and adds speed.
“More clients are indicating they want textiles to be engineered in near-net shapes or as close to the finished product as possible in order to decrease post-processing steps for the device engineer,” said Woltman. “This presents an engineering opportunity because all textiles areinherently formed using a continuous manufacturing process, so making adiscrete unit can be challenging. It requires us to rethink the design of the products we manufacture and anticipate how the textile structure will be incorporated into the final device. To that end, we have brought intextile design engineering talent to work closely with our clients to understand their design and assembly process. It becomes our engineering and design team’s job to translate these needs into a very specific fabric geometry.”
Within the orthopedic market more textile structures are being designed for sports medicine applications, such assuture-based textiles, anterior cruciateligament repair and rotator cuff repair.
“There is also an increased focus on textiles with higher-strength properties, lower profiles and a certain level of specialization within orthobiologics to aid in the treatment of joint and cartilage degeneration, tendon and ligament repair and bone grafting,” added Woltman. “We engineer a combination of materials into the textile structure or scaffold upon which the client can attach their biologic material to or within a containment structure to affect the biologic repair.”
There are several other new devices and technologies on the market that target joint preservation and joint repair, with the objective of saving the patient from going through joint replacement (or at least
delaying it). For example, Zimmer’sDeNovo NT Natural Tissue Graft is ajuvenile cartilage allograft tissue implant that provides an early intervention option for the repair of articular cartilage. Itconsists of particulated articular cartilage with actual living cells. The implantprovides a single-stage procedure to treat articular cartilage defects in a wide range of anatomical applications including knee, ankle, hip, shoulder or elbow. Introduced in 2009, more than 3,500 DeNovo NTprocedures have been performed.
“In 2012 Zimmer introduced Chondrofix Osteochondral Allograft for therepair of osteochondral lesions in diarthrodial joints in a single-stage procedure,” said Clark. “The allograft is minimally manipulated using a proprietary process which results in viral inactivation and terminal sterilization. The product features a two-year shelf life, allowing for off-the-shelf use in situations where a pre-operative MRI has not revealed the full extent of the injury. The technology is designed forpatients with osteochondral lesions who are considered too young for a total joint replacement or who may need to reduce rehabilitation time to a minimum.”
Design engineers increasingly are expected to provide more complex, near-net-shape components within a shortened development time frame. OEMs also are asking for qualifications and validations for the entire process (including the biomaterial) to be completed earlier in the development phase to meet their fast-paced development cycles.
“OEMs want the product right the first time in as near net shape as possible,” said Woltman. “Therefore, more interaction and collaboration between our engineers and our clients’ engineers is critically important at the beginning of the development process. To accommodate these needsSecant Medical engineers are engaging in more process and prototype analysis, such as tensile testing and data collection and analysis on early stage prototypes.”
At the start of each project medicaldevice contract manufacturers must dedicate the time and resources necessary to completely understand each client’s unique situation, design and budget constraints and schedule for development and launch.
“This often means helping themunderstand the risks and rewards ofcertain design paths in order to optimize their device development,” said Woltman. “Clients need to know that a device is worth pursuing up front and want to beassured that the component meets qualifications from the beginning of development—not as an afterthought.”
For Greatbatch Medical, the best way to support customers in getting their new products to market quicker is throughadditive manufacturing (or rapid prototyping) technologies,” according to Davies.
“We have both direct metal laser sintering (DMLS) and 3-D printing capabilities that give us great advantages in the quick evaluation and visualization of design,” Davies added.
Direct metal laser sintering is an additive metal fabrication process where a 3-D CAD file is sent directly to the DMLSmachine’s computer system. The file’s specifications then are configured to construct the part. This final “build file” isprogrammed with all the necessary parameters, including the thickness of each layer of the additive process (typically about 20 micrometers). The metal powder is spread evenly over the build platform with an automated arm.A high-intensity fiber-optic laser inside the build chamber then fuses the metal powder into a solid layer of metal. The next layer of powder is then spread on this first layer of fused metal and the process is repeated. As the layers accumulate the part takes shape. DMLS is precise enough to produce complex geometries from CAD data, typically within half a day, from almost anypowdered alloy, without any extra tooling (ideal for short runs).
Because DMLS is a net shape process the parts are produced with high precision and tight tolerances, good surface quality and functionalmechanical properties. Probably the biggest advantages of DMLS over traditionalmanufacturing systems are speed and theability to rigorously test prototypes.
An Objet machine (www.objet.com) is a 3-D printing device that creates highly realistic visual and functional rapid prototypes. More than 60 materials are available that can simulate properties ranging from varying grades of rubber to clear transparency to rigid, ABS-grade engineering plastics. An Objet machine is good for making smaller prototypes with thin walls (0.6 mm and even thinner) with high
accuracy (+/- 0.1 mm). Medical deviceprototypes that commonly are produced are implants, drug delivery systems, diagnostic equipment, laboratory instruments, surgical devices and pharmaceutical packaging. Objet also can be used to test biocompatible materials. After creating and studying the prototypes of their products or components, designers and engineers can quickly incorporate any modifications into their CAD files, building speed into the production process.
Orthopedic OEMs constantly seek high-strength, high-performance device designs with lower profiles. For biomedical textiles, clients want thinner, stronger fabrics for orthopedic designs as well as fabrics engineered into complex geometries that better conform to the body. OEMs are serious about searching for the most cost-effective yet high-performing products and will shop multiple suppliers to find the solution that balances cost with performance.
A recent trend in biomedical textileengineering is incorporating hybrid materials in textile structures to enhance orimprove performance, such as a metalintegrated with a polymer, a polymer with a resorbable material or potentially aresorbable material with a metal.
“Hybrids help leverage different physical and mechanical properties for textile structures that a single material simply cannot achieve,” noted Woltman. “Hybrid materials can push the device design envelope further by posing limitless possibilities in biomedical textile structures with complex geometries and custom designs to leverage specific biologic responses due to their unique properties. Additional innovations that affect efficiency in biomedical textile engineering include post-processing technologies such as ultrasonic welding and laser cutting techniques.”
Secant Medical has access to a wide range of advanced metallic and polymeric raw materials.
“All materials we select are capable of passing biocompatibility testing once they undergo a thorough cleaning process,” said Woltman. “No two biomedical textiledesigns are exactly alike and, as a result, the density of the structure, the materials used and the physical characteristics of the fabric makes each fabric react differently to a uniform cleaning process. It is vital to leverage our material science knowledge to evaluate the effect of our custom manufacturing processes on the chemical, biological and physical characteristics of each fabric that we design for our clients.”
Some of the biomaterials Secant Medical uses for device component design include resorbables such as polyglycolide, poly-L-lactide, polyhydroxyalkanoate, nitinol, ultra-high-molecular-weight polyethylene fiber, polyethylene terephthalate (polyester) and PEEK (polyetheretherketone).
“Resorbables are in more of an exploratory stage of use within orthopedics and are mainly seen within orthobiologic application areas,” said Woltman. “PEEK is now being extruded into yarn form that can be engineered into a soft textile implant.”
Recently, Secant Medical and SolvayAdvanced Polymers, a global supplier of high-performance polymers, formed amarketing partnership to promote thedevelopment and production of implantable biomedical fabric structures made of Solvay’s Zeniva PEEK fiber. The collaboration willresult in the formulation of a new supply chain that will provide medical OEMswith the option of developing customimplantable fabrics made of Zeniva PEEK for therapeutic devices in orthopedics, cardiovascular, tissue engineering, neurology and general surgery. Solvay's Zeniva “soft” PEEK provides a modulus very close to that of bone and has excellent biocompatibility, toughness and fatigue resistance.
Advancements in material science have the potential to address many of the long-term challenges in orthopedics, especially biologic fixation and wear. Some of theadvanced materials Zimmer offers include trabecular metal technology, a highly porous biomaterial that resembles the structure, function and physiology of trabecular bone.
“This novel material supports bone formation, enabling biologic fixation and a stiffness similar to cancellous bone,” said Clark. “The elasticity of trabecular metal technology provides more normal physiological loading which has the potential to decrease stress shielding and improve long-term implant fixation.”
Other material advances include antibacterial materials (silver, copper) that are incorporated into implants to preventinfection. Zimmer also has created a next-generation, highly-crosslinked polyethelene formulated with vitamin E. Currently available in Europe, this new formulation
provides antioxidant protection and results in a more durable, longer-lasting product.
Ceramics is a rapidly evolving science that continues to engineer hybrid materials for high-performance applications, especially hip and knee replacements that bear a lot of weight. These unique materials can be designed to have specific physical properties such as strength, optical and magnetic characteristics, conductivity and biocompatibility. Ceramics can be hardened with zirconia or alumina to be thermally insulating and corrosion-resistant. Integrating steatite and cordierite into ceramic structures canimprove thermal expansion, thermal shock resistance and electrical insulation.
Polymer ceramic hybrids also can be designed with precision microstructures that are ideal for spinal procedures and femoral implants.
Resorbable polymers can be incorporated into ceramics to modify bioactivity forspecific applications.
Groundbreaking research is being conducted in the emerging field of supramolecular polymers, which are compounds connected by weaker, non-covalent bonds. Because these bonds are easier to manipulate, scientists can create polymers with unique combinations of order and flexibility that allow them to interact more dynamically within their environments.
Samuel I. Stupp, a professor of materials science and engineering at Northwestern University, is a leader in this field of research.
“Over the past decade we have demonstrated some of the most bioactive materials ever reported by making supermolecular polymers and giving them structures that can signal cells,” Stupp said.
Recent successes include an injectable gel that promotes the growth of new cartilage and strings of aligned supramolecular polymers that can be surgically placed to repair tissues in organ systems.
“This field shows great promise fordesigning new materials, including highly sustainable forms of materials and highly bioactive materials for medicine, renewable energy and sustainability,” he said.
(Editor’s note: For more information onmaterial development, see this issue’s previous feature.)
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. Contact him at email@example.com.