Medical Edition 2014
Issue 3, No. 1
Lightning-Fast Laser Boosts Implant Surface Properties
Leading-edge metal surface treatment technologies being pioneered at the Institute of Optics, University of Rochester, NY, holds the promise of creating enhanced biocompatible properties for the next generation of titanium medical and dental implants. Professor Chunlei Guo said the centerpiece of his research and development efforts is based on a titanium-doped-sapphire, “femtosecond” pulsed laser, one of the most advanced lasers in the world. Professor Guo defined a femtosecond (10-15 second) as a “millionth of a billionth of a second”—an unimaginably fast speed. When applied to a metal substrate, the pulsed output of the laser can create a variety of micro- and nano-level surface structures, “dramatically increasing” the biocompatibility of titanium implants to sustain bone growth (osseo-integration) and integrate with human tissue, Guo explained. The same technology also can be employed to improve the hydrophilic properties (the ability to attract water and body fluids) of titanium implants, once again to tailor biocompatibility properties depending on the needs of the particular application. The femtosecond laser technology has successfully demonstrated the ability to improve the biocompatibility of titanium implants, according to Guo. The next step would be for the research lab to establish business alliances in order to scale up the process and demonstrate its ability for high volume commercial use. Guo “welcomes interest” from the titanium industry and already has received inquiries from potential partners. To create a system for commercial applications, he estimated the investment would be around $1 million for the laser, in addition to other instruments and production devices. In recent years the institute’s technology and Guo’s work have been profiled in feature articles published by The New York Times. Originally, the femtosecond laser technology was designed to boost the optical surface properties of metals, making substrate components more effective in applications involving sensors, commercial and industrial lighting, and solar energy. Eventually, further examination of the process revealed the laser technology also could be used to improve the biocompatible surface properties of titanium implants. The Institute of Optics was founded at the University of Rochester in 1921 to train scientists and technicians to support growth at the Eastman Kodak Company and the Xerox Corporation. The mission for the institute in those early years focused on research to develop better camera lenses and mirrors for commercial and industrial cameras and imaging equipment. Guo received his Ph.D. in Physics from University of Connecticut in 1999 and earned his postdoctoral training at Los Alamos National Laboratory, NM. In 2001, he was awarded the Postdoctoral Publication Prize in Experimental Sciences. He joined the faculty of University of Rochester in 2001 and his research led to the discoveries of the so-called “Black and Colored Metals,” which was profiled by The New York Times and other publications. He has published over 100 scientific refereed journal articles and is an elected Fellow for the American Physical Society, College Park, MD, and the Optical Society of America, Washington, DC.
Titanium Plasma Spray Coating Used for Spinal Fusion Implants
Aurora Spine, Carlsbad, CA, has received (FDA) 510(k) clearance for its sterile-packed titanium plasma spray coated TiNano™ spinal fusion implants. The spinal fusion implants are manufactured from poly-ether-ether-ketone (PEEK), a high-performance engineering thermoplastic, which are coated with commercially pure (CP) titanium powder during a titanium plasma spray coating process. Trent J. Northcutt, Aurora Spine president and chief executive officer, said the TiNano “intervertebral” implants support the entire spine, from cervical to lumbar, and accommodate the company’s ZIP™ minimally invasive Inter-spinous Fusion System product portfolio as well as other fusion products currently on the market. Development of the PEEK implants began in the late 1990s, Northcutt recalled. He said the implants, in effect, create support “scaffolding” for vertebral bodies (bones in the spine). However, while the product development initially showed promise for patients requiring spinal fusion operations, the medical community expressed concern that the PEEK didn’t integrate well with the body—a condition described as “tissue encapsulation.” Northcutt said Aurora’s solution to this problem was to coat the implants with the TiNano material via plasma spray process. Bone ingrowth is achieved due to the porous structure of the plasma spray coating. Because of titanium’s well-documented biocompatible capabilities as a medical implant material of choice to promote bone growth, the plasma spray coating “creates an ideal environment for healing and osseo-integration, along with the postoperative imaging advantages of PEEK,” Northcutt said. “We’ve developed superior surface coating of the PEEK implants using plasma spray. It creates a strong bond. This is a nice marriage of two materials (titanium and PEEK).” Northcutt underlined the importance of the FDA clearance as a “major achievement for the company.” He said the FDA clearance, announced Feb. 4 on Thompson Reuters ONE, also includes several interbody fusion devices, including configurations for anterior cervical, anterior lumbar, posterior lumbar, transforaminal lumbar and direct lateral interbody spacers, all of which are applications that will utilize the plasma-spray coated TiNano material.
Nexus TDR Develops Titanium Spinal Disk Replacement
Nexus TDR, Salt Lake City, Utah, has developed FlexBAC, a titanium compliant-mechanism design for total disk replacement that is capable of replicating the moment-rotation response of natural spinal disks, as well as the location and path of the helical axis of motion. “Compliant mechanisms are devices that move because of the deflection of one or more components,” says Peter Halverson Ph.D., Senior Engineer at Nexus TDR. “The motivation for the work stemmed from the observation that achievement of a natural quality of motion could be simplified through the use of compliant mechanisms.” By combining structural and elastic elements, compliant mechanisms enable a reduced number of parts. When made of titanium, they also provide resistance to harsh or corrosive environments, higher precision, and wear-free motion. Combined with careful design, compliant mechanisms facilitate ease of miniaturization, tailorable axes of rotation, and tailorable force-deflection responses. One of the greatest challenges of compliant mechanisms is that they provide motion through deflection, which couples motion with stress. Therefore, to prevent fatigue failure, materials such as titanium must be chosen. “Titanium exhibits well-known fatigue and creep characteristics which, when used with compliant-mechanism design techniques, can provide for an implant capable of an infinite fatigue life,” says Dr. Halverson. “The compliant nature of the implant also indicates the potential for elimination of the motion that induces wear.” Motion in the device is generated through elastic deformation of the flexures, making it a compliant mechanism. As the device is displaced, the flexures are transferred from one surface to another, creating a rolling motion. Due to the fact that the mechanism rolls without slip and its low hertzian contact stress, which refers to the localized stresses that develop as two curved surfaces come in contact, Ti-6Al-4V can be used without generating wear from articulating surfaces. The diagram shows generic geometry with a constant radius, but the quality and quantity of motion of the mechanism may be modified by changing the geometry of the mobile center and flexures. This has been done for both cervical (upper neck) and lumbar (lower back) embodiments, as shown in the diagram. “Testing has shown that these devices are capable of reproducing the complex moment-rotation response, helical axis of motion, and range of motion of the healthy intervertebral disks,” says Dr. Halverson. In addition, numerical modeling has shown that by doing so, the stress on the index and adjacent levels and surrounding soft tissue is reduced. “By incorporating Ti-6Al-4V’s well known fatigue properties and crack propagation rates, these can be designed to last the lifetime of the patient.” Nexus TDR was founded with the goal of improving patient care through the accurate replication of spinal biomechanics. The FlexBAC satisifies this goal by incorporating a rolling contact joint and leaf spring, as well as the well-known Ti-6-4 alloy, which has a long history of biocompatibility. By limiting wear, FlexBAC has opened new doors to the use of titanium in spinal arthroplasty.
Russamer Focuses on Eco-Friendly Electropolishing
Russamer Lab LLC, Pittsburgh, having established the benefits and capabilities of its automated, environmentally friendly electropolishing line for Grade 5 titanium medical components, is installing systems and licensing its technology throughout the world. Anna Berkovich, owner of Russamer Lab, described the technology as an acid-free, eco-friendly, plasma electropolishing system. “Different titanium alloy types require different electropolishing regimes and different electrolytes,” Berkovich said. “We can electropolish and install production lines for all alloy types: pure titanium (grades 1-4), Ti6Al4V (grade 5), beta-alloy, and other less popular titanium alloy types.” She said the technology can be applied to titanium powder injection molding components as well as stainless steel and nitinol (a titanium/nickel alloy). The electropolishing technology also can be used for heat-oxide removal. This year Russamer is installing a new electropolishing system at BioMechanical Laboratories S de RL, Chihuahua, Mexico. Russamer is also currently working with an Israeli company on installation of anodizing line for titanium dental implants. The proprietary anodizing is designed to promote better osseointegration for dental implants. Russamer recently installed titanium processing facilities, including eco-friendly descaling to electropolishing, at BAMA Technologies, Italy, and launched electropolishing at the European producer of nitinol laser-cut stents. Last year a South Korean company licensed Russamer technologies for cleaning, electropolishing and passivation (coating a metal surface to reduce chemical reactivity) of nitinol wire-knitted stents. In 2007 the B&G Manufacturing, Hatfield, PA, installed an eco-friendly titanium coloranodizing processing line for medical implants. Another facility near Philadelphia has utilized the technology for 24/7 continuous nitinol wire electropolishing for more than six years. Founded in 1996, Berkovich said Russamer’s mission is to develop environmentally safe technologies for surface finishing of medical implants. “Russamer selects the challenges of surface finishes that exist in medical design and manufacturing, and by involving engineering and chemical specialist, tries to solve the problems in most environmentally friendly way, when possible.” she explained. In 2012 the company was nominated for the International Titanium Association’s Application Development Award. Russamer’s titanium electropolishing technology “has provided several continuous process improvement successes with our organization,” an executive at Accellent Inc., Orchard Park, NY, stated in an endorsement form. Advanced Surgical Design and Manufacture Ltd. (ASDM), an Australian producer of cobalt-chrome medical devices, also offered words of praise for Russamer. “We have worked with Russamer since 1998 in Australia, Russia and China,” an ASDM executive wrote. “We have taken a number of metallurgical and polishing problems to them…and they have never failed to deliver for us.” As a result, Russamer helped ASDM develop a knee prosthesis treatment.
Medical Implants Support Healthy Growth for Global Business Opportunities
Medical applications for titanium implants represent a growing global market that should continue to expand in the near term, given the needs of the aging Baby Boomer population in the United States and the emerging middle-class populations in China, India and Brazil. According to statistics gathered by the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD, a unit of the U.S. Department of Health and Human Services, there were 644,000 knee replacements and 410,000 hip replacements in the United States in 2011 (the most recent year of available statistics), compared with 264,300 knee replacements and 258,000 hip replacements in 1997. An AHRQ spokeswoman said that, for U.S. patients, the average bill is just above $54,000 per knee and $59,500 per hip. Jack E. Lemons, Ph.D., professor and director of laboratory surgical research at the University of Alabama at Birmingham, said that while titanium alloys compete with cobalt alloys, they remain a material of choice for many joint, dental and cardiovascular implant applications such as hips, knees, tooth roots, heart valves and stents. “These treatments provide a significant quality of life benefit for the aging population. They minimize pain and maximize function. The implants deliver cost-effective, proven outcomes.” Compared with alternative materials, Lemons said titanium’s main advantage as an implant material is its ability to integrate with bone and other tissues. In addition to aerospace titanium alloys, Lemons noted the use of special grades for implants such as titanium/zirconium, titanium/molybdenum and titanium/nickel. He said a new frontier in the medical field will be regenerative technologies and the use of tissueengineered implants, but added that much research is still needed and it’s unclear whether titanium will play a major role in that field. Dental implants must survive an extreme environment of high stress and aggressive chemical attack. Titanium materials are the leading choice for dental implants due to their balance of desirable properties; strength, biocompatibility, density, osseointegration, and surface morphology. At the upcoming TITANIUM EUROPE 2014 conference, Ric Snyder, Product Manager for Fort Wayne Metals, will be discussing how the presence of the potentially toxic vanadium and the limitations of the surface texture of this material, have created alternatives sought by the industry. Mechanical properties, grain structure, texture, surface morphology, fatigue properties, and machinability have been studied to characterize a new material alternative. Jeff Wise, vice president of sales for Titanium Industries Inc., Rockaway, NJ, said that while Europe and the United States represent the largest markets for titanium medical device and instrumentation applications, there is growing demand among consumers throughout Asia and Latin America. “With a growing middle class in many parts of the world, there are many consumers in various global markets that are electing to have an operation for a new hip or knee.” He estimates medical applications represent about 5 percent of the global demand in the titanium market. Powder Metal Technology Sources say there is an increasing amount of research and development funding going into powder metal and additive manufacturing research to design and produce titanium implants. Powder metal represents the technology vanguard for titanium implants, given the capabilities for design/production flexibility. However, sources declined to provide details, citing the proprietary nature of their development programs. Stanley Abkowitz, founder and CEO of Dynamet Technology, Inc. said the company has continued its manufacture of its CermeTiR titanium matrix composites (Ti MMC) for medical device use. As he presented during the Medical Panel of TITANIUM2013, this includes production use in Medtronic’s PrestigeRLP artificial spinal disc. (Figure 1) This device is used commercially for years outside the US and its release in the US is anticipated this year. This nextgeneration device permits the use of titanium material to be used in place of the stainless steel material design used in the predecessor device. The Titanium MMC combines titanium’s desirability for biocompatibility and imaging characteristics, now with wear resistance like the steel. A video showing this device can be found at: http://www.prestigedisc.com/intl/playvideo. html?filename=prestigehi. Dynamet Technology continues to innovate with novel powder metal enabled compositions that can extend the use of titanium materials to new applications that would otherwise require more materials such as stainless steel or CoCr for wear resistance or other properties not capable of being met by conventional titanium alloys. Haden Janda, senior materials engineer, Advanced Surgical Devices, Smith & Nephew Inc., Memphis, TN, pointed to his company’s use of porous titanium coatings on forged implants to serve as the interface to promote enhanced “bio-fixation” or bone ingrowth for hip and knee replacements. He said the porous coatings, which involve sintering spherical or asymmetric commercially pure titanium beads onto the bone-contacting surface of implants, are designed to promote osteoconductive (bone growth) attachment. The focus on powder metal titanium and porous coatings offers cost advantages along with the ability to manufacture design-driven implants not possible with conventional manufacturing techniques, according to Janda. “Porous coatings are quite prevalent in the industry,” he confirmed. “Porous coatings are the standard of care for primary hip procedures. Non-porous is the standard of care for primary knees with porous gaining in popularity.” Janda noted that titanium metal injection molding and additive manufacturing products represent mid-term development fields for titanium implants. Powder metallurgy is the leading edge of material development for medical implants, according to Michael Roach, Ph.D., assistant professor, biomedical materials science at the medical center of the University of Mississippi. Compared with wrought titanium parts, Roach said powder metallurgy opens up new possibilities in terms of tailored alloy combinations and potential cost savings (by avoiding machining/tooling challenges and scrap generation). “Conceptually, powder metallurgy offers significant advantages for implants,” he said, “but we are still verifying whether the powder metallurgy processing methods produce materials with mechanical properties comparable to their wrought metallurgy counterparts.” Roach did cite interest in the use of titanium alloys with a 15-percent molybdenum content (ASTM spec F 2066) for wrought surgical implants (with molybdenum serving as a beta stabilizer for the alloy’s ductile phase). New generations of alpha/beta alloys also hold promise for implants that need to offer enhanced stiffness and ductile mechanical properties compared to beta titanium alloys. However Roach pointed out that alpha/beta titanium alloys still present lower stiffness values compared to the cobalt chromium alloys, which are often used for hips and knees. Removing Cost from Supply Chain Lemons acknowledged the use implants will play out against the current backdrop of healthcare politics and the global economy. “Yes, there are a lot of cost pressures, both medical and legal. I know that there are generic choices for implants as one way to control costs. There are generic options, but I don’t see generic implants as the best option. Medicine always uses the best products for specific needs. There’s risk in innovation and the innovations in the global supply chain may not come from the United States. Our country is trying to improve its overall competitiveness in the medical field and titanium implants are an important part of that.” Carlos Toledo, global commodity manager for the Implants Division of Stryker Corp., a designer and manufacturer of medical devices based in Kalamazoo, MI, said that due to a variety of factors— such as uncertainty over the recent launch of the Affordable Care Act in the United States as well as the stagnant economies of the European Economic Union—there are strong downward cost pressures in the medical sector. Toledo praised the titanium industry as a partner in this ongoing effort to contain costs in the supply chain. For example, he said titanium producers and mill products suppliers “have done a tremendous job in getting the supply of metal closer to our manufacturing operations (in Europe).” Toledo also cited the trend of supplier consolidation, noting that from 2010 to 2013 there was a 30-percent decline in the number of suppliers in the medical supply chain. Another concern voiced by Toledo involves managing the cost associated with titanium scrap. Stryker has launched initial efforts for a closed-loop scrap program for its cobalt/chrome implant production. As for revealing Stryker’s development efforts for medical implants, Toledo said only that interested observers should closely monitor the company’s recent acquisition moves. In March 2013 Stryker completed its acquisition of Chinese-based Trauson Holdings Co. Ltd. Trauson is a producer of surgical instruments and implants for spine and trauma injuries. In September 2013 Stryker acquired Mako Surgical Corp. and its robotic-surgery platform for knee and hip implants. Like Toledo, Robert Daigle, senior vice president with Structure Medical LLC, a Naples, FL, subcontractor that produces medical implants, also sees downward pressure in the supply chain on pricing for medical devices in the United States. According to Daigle, the U.S. government, through Medicare and Medicaid, has made it clear that the existing cost structure must change. “The cost for insurance from private insurance companies continues to rise with more of the cost being shared by employers and employees,” he said. “Hospitals are in motion, acquiring physician offices and surgery centers. Hospitals are stopping short of telling doctors what devices they can use, but new purchasing teams and industry buyer groups are participating and having more influence on buying decisions.”
Magnetic Implant ‘Attracts’ Attention, Offering Relief from Reflux Symptoms
Torax Medical Inc., Shoreview, MN, continues the successful rollout of its LINX™ Titanium Reflux implant, which received U.S. Food and Drug Administration (FDA) approval in March 2012. As described in Torax’s information overview for the FDA, the LINX implant is a series of titanium beads, each with a magnetic core, connected together with titanium wires to form a ring shape. The device is surgically implanted around the lower end of the esophagus (the lower esophageal sphincter muscle—just above the stomach) to treat gastroesophageal reflux disease (GERD) and chronic acid indigestion. Brian Scovil, Torax senior vice president of operations, explained that while the LINX device prevents stomach contents from flowing back into the esophagus (reflux), it doesn’t restrict movement of food or liquids down the esophagus into the stomach. He described LINX as a “simple and elegant” mechanical solution to help alleviate the GERD condition, offering patients an alternative to long-term drug use or anatomy-altering surgery. Titanium was selected for LINX because of its strength, biocompatibility, and proven performance as a medical implant, according to Scovil. The LINX device is composed of 12 to 16 commercially pure (CP) titanium bead “cases,” which house magnets. The beads form an elastic chain, linked via titanium wire and washers. LINX is designed to support a weak sphincter, providing relief for many patients with severe, recurring heartburn symptoms and reflux and may reduce or eliminate drugs typically needed to treat these symptoms. Citing the FDA overview on LINX, Scovil said that when the patient swallows, pressure in the esophagus increases and the magnetic beads move apart on the titanium wires. This separation of the beads allows food or liquids to pass normally into the stomach. After the food or liquid shave passed into the stomach, the magnetic beads attract and enable the device to return to the closed position, which prevents abnormal amounts of stomach acid from flowing into the esophagus. In effect, LINX mechanically mimics the opening/closing function of a normal sphincter muscle in the lower esophagus. LINX targets patients who would be considered candidates for anti-reflux surgery. According to information posted on various medical websites, GERD affects up to 40 percent of the U.S. population on an occasional basis (once a month) and 10 to 20 percent of the population on a more chronic rate (once or more a week). It’s estimated that as many as 20 million Americans take medication for GERD on a daily basis. To date, there are over 1,600 LINX implants worldwide. As sales of the device continue to expand, the company is ramping up a production line, which includes laser welding and assembly of the device. Torax, founded 11 years ago, has been dedicated to the research and development of LINX. Bolstered by the success of the LINX project, Scovil said the company currently is working with physicians in Europe to expand the use of a titanium mechanical device (FENIX™) to address adult incontinence issues. Scovil has been involved in medical device design for more than 25 years and submitted LINX for consideration for the International Titanium Association’s 2013 Applications Development Award. For additional information contact: Torax Medical Inc. 4188 Lexington Ave N Shoreview, MN 55126 Phone: (651) 361-8900 Website: www.toraxmedical.com
Integra Titanium Bone Wedges Receive Clearance from the FDA
Integra LifeSciences Holdings Corp., Plainsboro, NJ, has received 510(k) clearance from the U.S. Food and Drug Administration (FDA) for its IntegraR Titanium Bone Wedges, designed for internal fixation for bone fractures or osteotomies (bone-cutting surgical procedures) in the foot and ankle. A company spokeswoman said commercial applications already have begun in North America and the company will expand distribution of the product this year. According to a company statement, the Integra Titanium Bone Wedges are used in corrective procedures, such as Cotton (opening wedge) osteotomies of the medial cuneiform and Evans lengthening osteotomies. The bone wedges are composed of commercially pure titanium formed into a cancellous-like structure that mimics the strength and porosity of human bone. A cancellous structure describes the region of interior bone that has a spongy, porous appearance. Wedges are available in 15 different pre-shaped anatomical sizes, to accommodate various skeletal deformities in the foot. The spokeswoman said the company “estimates there are several thousand of these procedures done annually to address posterior tibial tendon dysfunction and flat-foot reconstruction. We anticipate significant penetration into this market with the Titanium Bone Wedge System.” She said the company believes the “porous titanium technology” does have potential applications for implants outside of the foot. “We’re very pleased that we can now offer surgeons another option to complete our flat-foot correction portfolio,” Robert Paltridge, Integra LifeSciences president, Extremity Reconstruction, said in the company statement. “Our Titanium Bone Wedges provide more stability over allograft wedges. Additionally, our extensive line of pre-shaped bone wedge implants does not require custom shaping, which helps reduce surgical time.” The company explained that osteotomies are procedures in which surgeons realign or remove a segment of bone located near a damaged joint to help correct deformities, typically in the foot. Bone wedges are designed to provide bone grafting material for osteotomy corrections. They create a scaffold for bone growth, as well as biologic stability and structural support for deformity corrections. Ancillary plates are used to hold bone graft material in place and prevent it from expulsion. Development of the Integra wedges began in late 2011. “The goal has always been to produce a product made from porous titanium, due to its proven clinical track record,” the spokeswoman said. She noted there are proprietary surface treatments used to manufacture the product, which enhance the stability of the implant. Integra wedges were featured at the American College of Foot and Ankle Surgeons annual scientific conference, which was held Feb. 27-March 2 in Orlando, FL. According to information posted on its website (www.integralife.com), the company’s line of orthopedic products includes devices and implants for spine, foot and ankle, hand and wrist, shoulder and elbow, tendon and peripheral nerve protection and repair, and wound repair. It also provides surgical instruments to hospitals, surgery centers and alternate-care sites, including physician and dental offices. Founded in 1989, Integra LifeSciences has 3,500 employees worldwide.
Medical Subcommittee Prescribes Objectives for Next Two Years
The International Titanium Association (ITA) has formed a medical subcommittee created to explore burgeoning opportunities in the international field of high-tech medical devices and instruments. The committee, led by chair Susan M. Abkowitz, has drafted a list of targeted objectives for 2014 and 2015 in conjunction with the general strategies of the ITA. The medical subcommittee is composed of executives from ITA member organizations, all which have an interest in seeing titanium use expanded for medical applications. In addition to Abkowitz, the group includes Fanny Carrillon of ACNIS International, Villeurbanne, France; Mary Downes, Titanium Industries Inc., Rockaway, NJ; Jeff Slater, Fort Wayne Metals, Fort Wayne, IN; and Tom Zuccarini, Dynamet Incorporated, Washington PA. “We have an active medical committee and members are enthusiastic about helping to grow awareness and future opportunities in this field for the titanium industry,” Abkowitz said. She serves as the chief operating officer and vice president of technology for Dynamet Technology Inc., Burlington, MA. Abkowitz explained that, guided by the two-year plan of targeted objectives, she and her subcommittee associates will work to increase visibility both within ITA and its publications as well as through marketing to other industry organizations and trade shows. She acknowledged that while titanium has long held a spot as a premier material of choice for the medical industry, there has been a distinct surge in business opportunities in recent years, with an even greater potential for near-term penetration into this sector. According a variety of industry analysts and observers, as well as companies involved in the design and production of titanium medical devices and implants, much of the anticipated international growth in the medical sector is due to two factors: the demographics of the aging “Baby Boomer” population in North America; and the rising demand for enhanced medical treatments in emerging consumer markets found in South America, Asia and India. Utilizing the support of the ITA as well as alliances with international partners, the medical subcommittee will look to build upon titanium’s existing strong base of applications in the medical field and identify areas for new growth. Much of the effort will involve expanded communication and outreach by the ITA to help educate designers of medical devices on the advantages of specifying titanium for new applications. As part of the two-year plan, the ITA has laid out a communication strategy for subcommittee activities through five points for 2014. First, this year the subcommittee will “collaborate on editorial topics for the ITA’s quarterly Titanium Update E-Newsletter and Titanium Today magazine.” Second, committee members have been charged with “maintaining the product & services categories in the ITA’s Titanium Resource Center to ensure there are no duplicates or unaccounted items.” The subcommittee will review incoming requests received by the ITA for new products and services relating to the medical business sector to determine what, if anything, should be added to the Resource Center. Third, the subcommittee will “discuss ideas for potential trade show recommendations on where the ITA should exhibit and prepare appropriate collateral materials for public distribution.” On this point, the group will make recommendations to the ITA’s trade show committee to consider the association’s participation in medical trade shows. In turn, the trade show committee will provide a copy of the show assessment form throughout the year for all medical related exhibits for the subcommittee’s reference and future consideration. Fourth, the group will “develop market specific general sessions, inviting appropriate panel speakers and make recommendations for distinguished speakers at future TITANIUM conferences.” Fifth, members of the committee will “solicit individuals or organizations that might qualify to apply for the annual Titanium Applications Development (TAD) award, sponsored by the ITA, and will submit a minimum of two nominations for the grant committee’s consideration.” Each year the sub-group will propose nominees by April 1. Three years ago, Synthes Spine Inc., a West Chester, PA-based unit of Synthes International, was the recipient of the prestigious TAD award, recognizing the development of the Vertical Expandable Prosthetic Titanium Rib (VEPTR) implant. Next year the medical subcommittee will focus on four activities: gather and recommend ideas for the promotion of titanium medical applications in the ITA’s literature and website content; outline organizations that are not yet aligned with the ITA and assist in the referral of individuals in those organizations who potentially might qualify for ITA membership; evaluate opportunities to assist in technical development within the titanium industry (non-proprietary alloys, specifications, etc.); and evaluate methods to address concerns of potential users of titanium and ensure an industry interest in their application, regardless of the size of the application, material used or market segment. Any Member of the ITA may join this sub-group. To learn more about becoming a member of the Medical sub-group or any other ITA committee, please contact Jennifer Simpson at 303-404-2221 or by email at firstname.lastname@example.org.
Titanium Orthopedic Implants at North Carolina State University
“Our research group at North Carolina State University has been involved in the fabrication of titanium orthopedic implants for approximately ten years,” says Dr. Denis J. Marcellin-Little, an orthopedic surgeon at the colleges of veterinary medicine and engineering. The team builds implants of grade 5 (Ti-6Al-4V) titanium alloy, by means of two additive manufacturing techniques: direct metal laser sintering and electron beam melting. “The impetus for development of DMLS and EBM custom implants was the complex geometry we could build with these technologies,” he explains. Such capability would allow repairing problems such as large skull defects and loss of long bones. It would also enable custom total joint replacement, and transdermal osseointegrated implants, all of which are too complex to be fabricated by traditional methods. Direct metal laser sintering (DMLS) is an additive metal fabrication technology in which a powerful fiber-optic laser is focused onto a bed of metal powder on a platform within a build chamber. Titanium powder is dispensed onto the platform in a thin layer about 40 microns thick, and the laser sinters and fuses the powder along a path dictated by a CAD program. Then a recoater blade moves a new layer of powder on top of the build platform, and the next layer is sintered. Thus the part is built up layer by layer into the final three-dimensional solid structure. The DMLS process facilitates the creation of very complex geometries derived from three-dimensional CAD data. The process is completely automated and is usually completed within a few hours. It accurately builds parts with tight tolerances, excellent surface quality, and high mechanical properties. Electron Beam Melting (EBM) is another powder-based process for the additive manufacturing of three dimensional parts. Rather than being sintered as in the laser process, the powder bed is selectively melted layer-by-layer by an electron beam under a high vacuum. The vacuum eliminates the possibility of oxidation, and enables production of parts made of reactive metals such as titanium. Each layer is melted to the exact geometry defined by a CAD model. The EBM process takes place in vacuum and at high temperature, producing stress-relieved components with material properties better than cast and comparable to those of wrought material. The vacuum system provides a base pressure of 1×10-5 mbar or better throughout the entire build cycle. During the actual melting process, a partial pressure of helium is introduced to 2×10-3 mbar. This controlled environment is important to maintain the cleanliness of the build material. For each layer, the electron beam heats the entire powder bed to an optimal ambient temperature, specific for the material. As a result, the parts produced with the EBM process are free from residual stresses and from martensitic microstructures. “The complexity of the implants we make has increased over time,” says Dr. Marcellin-Little. “They now may include coarse meshes to decrease the implant modulus. They also allow the growth of musculoskeletal soft tissue and subcutaneous tissues through loose titanium meshes as part of transdermal osseointegrated implants.” Tests have confirmed the biocompatibility of titanium alloy surfaces with mesenchymal stem cells, dermal fibroblasts, and keratinocytes Researchers are currently investigating the development of advanced titanium implants for limb-sparing procedures. These implants have a low modulus to decrease loads at bone/implant interfaces, conforming geometry, and ingrowth/ongrowth surfaces. “We are also investigating the potential of titanium alloy implants in custom joint hemiarthroplasties,” adds Dr. Marcellin-Little. “For these applications, a highly conforming artificial joint surface articulates with native articular cartilage.” Until recently, titanium has been the preferred material for implants that rely on bone ingrowth, whereas cobalt-chromium has often been selected where higher as-cast mechanical properties are needed. However, additive manufacturing can now produce titanium components with improved mechanical properties, making titanium the material of choice for most custom implants. In cases where implants have a need for both bone ingrowth surfaces and articulating bearing surfaces, coatings such as titanium nitride are now available that improve titanium bearing surfaces to equal the bearing surfaces of cobalt-chromium. NCSU researchers anticipate that additive manufacturing processes will change the implant industry for custom implants, enabling solutions that function far beyond the capabilities of implants made by traditional methods. The team at NCSU will help speed this development, and has already collaborated with BioMedtrix LLC, Boonton, N.J., which has commercialized an EBM-fabricated acetabular cup for dogs.
Lima Develops Trabecular Titanium to Imitate Natural Bone
“We make our implants of titanium because of its unique combination of resistance to corrosion, high biocompatibility, and excellent mechanical properties (Figure 1),” says Michele Pressacco, Product Development Director at LimaCorporate, “especially its resistance to fracture and fatigue.” LimaCorporate engineers took advantage of electron beam melting technology to add even more favorable properties by creating a strong bone-like porous structure from titanium powder. Called Trabecular Titanium, it has a three-dimensional, multiplanar, regular hexagonal cell structure characterized by a high open porosity. This structure imitates the morphology of trabecular bone (Figure 2), and promotes the ingrowth of natural bone. As a result, it provides extremely high implant stability with superior osteointegration characteristics. Human bone is composed of a hard solid outer bone called cortical bone, and a less-hard porous inner structure called trabecular bone. The structure of this inner bone is an irregular three-dimensional array of boney rods and plates called trabeculae. “Trabecula” is Latin for “small beam” or “strut,” and is an accurate description of the microscopic structure of the inner bone. The struts in the Trabecular Titanium microstructure were given surface roughness (Figure 3) that further promotes attachment, proliferation, and differentiation of anchorage-dependent bone and tissue-forming cells. “It has been demonstrated in vitro that human adipose stem cells grown on trabecular titanium are able to adhere (Figure 4), proliferate, and differentiate into osteoblast-like phenotypes (Figure 5), thus producing a mineralized extracellular bone matrix (Figure 6),” explains Mr. Pressacco. In this way, damaged tissue can be regrown (Figure 7), and bone function can be restored. Of course, the structure of bone and the advantages of a material with a similar structure have long been known, but it was not until the development of additive manufacturing technologies such as electron beam melting (EBM) that it became possible to make such materials. EBM is a powder metallurgy technique in which a powerful beam of electrons strikes metal powder in a special high-vacuum build chamber. The powder is melted in very thin layers according to a CAD model, building up the layers until the part is complete. The technology enables creation of any threedimensional design. LimaCorporate has advanced the technology to optimize cell size for effective osseointegration while ensuring mechanical properties suitable for a long-lasting implant. Over 37,000 of LimaCorporate’s acetabular cups of trabecular titanium have been implanted all over the world, and the number continues to grow. “We have applied Trabecular Titanium technology to a unique and complete system of acetabular cups (Figure 8) that can be adapted to a variety of different clinical indications,” says Mr. Pressacco. “Each offers maximum stability and excellent recovery of the biomechanical parameters of the joint.” To maintain this production, Lima Corporate has more EBM installed systems than any company in the world, with an annual consumption of more than 5000 kilograms of titanium. Lima Corporate’s Trabecular Titanium provides an advanced cellular solid structure that has been shown to be effective as a scaffold to regenerate damaged bone tissue, and in orthopedic applications to promote osseointegration. The material expands the use of titanium in regenerative medicine, especially in bone tissue engineering, with a new generation of scaffolds to stimulate the growth of bone on trabecular titanium constructs.