Additive Manufacturing: Hype or Future Hope for Orthopedics?

Science-fiction writers are the consummate visionaries. Collectively, they’ve conjured up countless numbers of inventions that ultimately have come to pass, from airplanes, spaceships and submarines to cell phones, electronic books, robots and computer eyewear (the latter novelty is marginal; Google Glass cannot store human memories like the spectacles worn by venture altruist Manfred Macx in Charles Stross’s 2005 novel “Accelerando”).

Many ideas, of course, are just too preposterous for the real world (pumpkin houses, ebony teeth, plant-grown meats and see-through pants immediately come to mind) while others are simply impracticable. For the most part though, science-fiction scribes have been fairly accurate prognosticators, especially about healthcare. Aldous Huxley, for example, presaged the arrival of genetic engineering back in 1931 and Philip K. Dick amazingly predicted the advent of spray-on skin in 1960. A dozen years later, Martin Caidin published “Cyborg,” the novel that inspired both a television series (“The Six Million Dollar Man”) and the evolution of bionic body parts.

Gene Roddenberry’s “Star Trek” franchise has been equally as influential, fostering the development of jet injectors (a parody of the high air pressure hypodermic injections administered by Dr. McCoy); handheld disease detectors (modeled after those nifty tricorders Spock and Captain Kirk used to survey new planets); and 3-D printing (based loosely on the “replicators” that kept the Enterprise crew clothed, well-fed and flying).

Otherwise known as additive manufacturing or free-form fabrication, 3-D printing creates objects through successive layers of material, fusing individual cross-sections (slices) of molecules until a complete product is formed. The concept of additive manufacturing is similar to Star Trek’s replicator, but the technology is markedly different—whereas the replicator worked by rearranging subatomic particles to form molecules and assemble them into desired products—3-D printing uses digital files generated by software design tools such as CAD (computer-aided design) to create microscopically thin layers (usually between 0.03 mm and 0.20 mm) that are melded into place with a liquid binder, thermal print head, laser or electron beam. As these layers build up, the desired 3-D object slowly takes shape.

Additive manufacturing has existed for nearly 30 years, but it traditionally has been used to make prototypes rather than finished products. Recent technological advancements, however, have broadened the scope of viably printable materials, thus enabling the machines to produce finished items from such substances as titanium, cobalt chromium, stainless steel and polyetherketoneketone (PEKK). 

Additive manufacturing is bound to become a big part of future orthopedics, considering the technology currently is being used by companies like Ala Ortho of Italy, MCP HEK of Germany and Arcam AB of Sweden to produce acetabular hip shells and customized implants for trauma surgery. At least 1,000 acetabular hip shells made by electron-beam melting have been implanted in patients over the last several years, industry research shows, though that number most certainly will rise as more manufacturers take advantage of 3-D printing to create customized device geometries, complex scaffold structures and porous surfaces that significantly improve bone ingrowth. 

Some 3-D systems even allow the properties and internal structure of the material being printed to be varied. Within Technologies, for example, offers titanium medical implants with features that resemble bone. The British firm’s femoral device is appropriately dense in areas where stiffness and strength are required, but it also has strong lattice structures that encourage osteointegration. 

Working at such a fine level of internal detail allows the stiffness and flexibility of an object to be determined at any point. The company currently is working to develop other lattice structures, including aerodynamic body parts for race cars and special insoles for stiletto-heeled shoes. 

While some experts doubt the ability of 3-D printing to reinvent or revolutionize manufacturing, others insist the enhanced performance of additively manufactured items will help drive the technology forward. The process already has proven itself in the craniomaxillofacial realm. Last year, Belgian additive manufacturer LayerWise NV built a 3-D printed lower jawbone that was implanted in an 83-year-old woman suffering from an infection. The 3-D printing made it possible to create a lightweight titanium implant with articulated joints, cavities that foster muscle attachment and grooves to guide nerve and vein regrowth. 

Oxford Performance Materials of South Windsor, Conn., had similar success with its 3-D-printed skull implant. Surgeons used the company’s OsteoFab Patient Specific Cranial Device within weeks of its U.S. Food and Drug Administration approval in late winter to replace 75 percent of an American patient’s skull. Few details of the surgery have emerged, and only basic information about the implant itself exists. According to a company news release, the OsteoFab device is comprised of PEKK, a biocompatible bone-like material that does not interfere with X-rays. The implant was printed using an EOS P800 laser-sintering printer. 

Oxford President and CEO Scott DeFelice called the OsteoFab technology “a highly transformative and disruptive platform that will substantially impact all sectors of the orthopedic industry.” Such an outlook perhaps explains the 13-year-old company’s plans to expand beyond the skull to other bone replacements, opening up the revolutionary new technology to a multimillion-dollar industry.

“We see no part of the orthopedic industry being untouched by this,” a jubilant DeFelice proclaimed.

If additive manufacturing is indeed transformational, then no part of the orthopedic industry will want to be untouched by it.