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Additive in Medical


quences of cancer surgery, car accidents, or gunshot wounds, among other traumas. “Tese 3D models have aided teams of surgeons in dramatically shortening the actual surgical time. It both reduces cost and trauma to the patient,” Wohlers said.


producing complex shapes and features, and cost,” answered Wohlers. What’s more, additive manufacturing can elimi- nate some finishing work required by conventional methods. “Tese cups need a rough, porous surface for bone in-growth,” Wohlers said. Conventional methods use an expensive and time-consuming sintering process on the outer surface of a cast or forged part. Besides the cost of this secondary process, manufacturers usually outsource the work. Lead-time can be significant while increasing inventory costs. “Using additive manufacturing means you can build that surface feature into the data,” Wohlers said, noting that solid and porous sections of the implant can be built in the same step. Another area of medical production where additive


manufacturing is making inroads is dental copings made from cobalt chrome, used for crowns and bridges. Wohlers said that “at least 15,000 of these are made every day,” with machinery provided by EOS (Krailling, Germany). Other dental items be- ing produced by additive manufacturing include: drill guides for placing implants, braces, partials, and dental stones.


Titanium hip cups feature a trabecular surface for good osseointegration and are made in a single step with EBM additive manufacturing.


A leading company in this endeavor is Medical Modeling


(Golden, CO), which has “done over 40,000 cases representing hundreds of thousands of models,” Wohlers said. While surgical aids and models use plastics common in the


field of additive manufacturing, the development of metal- based additive manufacturing has opened up the field of metal implants to additive manufacturers, too. Wohlers points, in particular, to metal acetabular hip cup


implants. “Magnus René, CEO of Arcam [Mölndal, Sweden], estimates that about 80,000 of these have been created using the company’s electron beam melting process,” Wohlers re-


Tech Transfer from Industrial Applications Wohlers notes that most of the 80,000 hip cups manufac-


tured to date use electronic beam melting (EBM), with some others made through laser sintering. Tese are processes that melt the powder in a bed that the machine lays down layer-by- layer. Both require elaborate support structures while the part is ‘grown.’ Arcam (Mölndal, Sweden) is a primary supplier of EBM machines. According to René, the CEO of Arcam, medi- cal was not the company’s first thought: “We were founded in 1997 and initially we worked with the tooling industry,” he said. “However, in 2003 we were contacted by the University of North Carolina, in Raleigh. Tey kind of pushed us into implants made with our additive manufacturing technology.” Aſter establishing the basis for the technology, they developed a partnership with the Lima Corp. (Udine, Italy). “Tey were the first to really get started with making implants in volumes


“The value of additive manufacturing is not in converting an existing process, but developing a design tuned for the process.”


ported. Te parts are made primarily from Ti6Al4V, a favorite titanium alloy used for medical implants because of biocom- patibility. Tese hip cups, fixed into the pelvis of the patient, are the part to which the bone stem mates and rotates around. “About 30,000 have been implanted into patients; the remain- der is inventory,” said Wohlers, noting that doctors want them on the shelves for rapid selection when needed. It is interesting that these are standard items. Unlike


the surgical guides, they are not customized to a patient’s unique geometry. So what is the advantage in using additive manufacturing? “Speed, on-demand manufacturing, ease of


58 Medical Manufacturing 2013


using additive manufacturing, around 2006,” René said, noting that Lima owns eight of Arcam’s EBM machines: “We believe that 2% of all acetabular hip cups worldwide are made with our machines, and most of those are made by Lima.” For press-fit implants specifically, Arcam says, the EBM process lends itself to high-volume production. René also stressed that Arcam makes many other medical


components with EBM technology as well—hip cups are just the most successful at present. With a number of customers making such implants he notes that about one-third of Arcam’s business is supplying


Photo courtesy Arcam


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