Manufacturing Life-like Parts of the Body
At first glance, Larry Ward's office looks a bit like Frankenstein's lab. "Visitors will walk by and I catch them doing a double take. That's a skull in the window, a foot or hand in the window." These skulls, jaws, and vertebrae aren't leftovers from a haunted house gone awry. They're 3-D replicas of human anatomy made out of plaster and resin. They're called BioModels and they're manufactured in Kannapolis by an Australian company called Anatomics. These medical models help surgeons take measurements and rehearse complicated surgeries - all before scalpel touches skin. Larry Ward is the CEO of Anatomics' U.S. operations. He picks up a clear resin model of a mandible or lower jaw bone. It's smooth and shiny, except on the left side where a large bumpy tumor juts out. "A surgeon can take this model, they can plan their surgeries, where they want to make their cuts to remove the tumor before they even get into the operating room," Ward says. These 3-D models can be used for a wide range of surgeries, from routine to high profile operations like the one Dr. Henry Kawamoto of UCLA's Division of Plastic Surgery performed in 2002. "Two infants were joined at the top of their heads and in order to plan the operation to separate them, we needed all the information we could get a hold of." Dr. Kawamoto says that without a 3-D model, preparing for a difficult surgery is a bit like putting together a mental puzzle. First he'd look at a series of CT Scans or detailed X-rays. "And then you have to put it together in your mind to stack these various pictures together to get a representation." Dr. Kawamoto wanted a physical model that he could pick up and examine from every angle. 'It's much quicker to see and feel and turn it around, physically in your hand." So he sent a CT scan of the infants' skulls to a medical modeling company like Anatomics. All of the information - every millimeter of those skulls - was transformed into a digital file that a machine called a Polyjet printer could understand. A Polyjet printer looks like an oversized photocopy machine with a piece of glass in the center. Underneath, a slim vertical band moves side-to-side, building the model one layer of resin at a time. Ward says it's a lot like building a loaf of bread - one slice at a time. "If you take that loaf of bread, stand it on end, each slice represents one printed layer of that model," Ward says. "So the instrument will print a layer and it'll drop a little. It'll print another layer, drop, until you have the full model. So you're building a model, or a loaf of bread, slice-by- slice." Once the model has hundreds of thin layers stacked on top of each other, the resin melds together, forming an extremely hard model. In the case of the conjoined twins, Dr. Kawamoto used the model to rehearse the most delicate steps of the surgery, all before the infants even entered the operating room. "Well what we did is actually divide the joint heads, the model, exactly where we were going to during the operation." When Dr. Kawamoto did go into surgery, he took the model in with him as a guide. "It gives you a very accurate representation of what you're going to see," Kawamoto says. Models are great because they don't have blood and all the other things there to obscure your vision, but it did give you a good picture of the terrain." Anatomics' Larry Ward says that having a piece of plaster or resin to reference during surgery instead of a computer image allows the surgeon to see and feel parts of the body that are still covered by skin. "Surgery is performed through an incision. If you take a model of someone's back, during the surgical procedure they may only have a portion of one or two vertebrae exposed. So a model would give the surgeon a much broader view of the patient's anatomy," he says. And there are other benefits, too. Studies have shown that 3-D medical models improve planning, diagnosis, and even save time in the operating room.