"Could 3-D Printing Enhance Your Joint Replacement Surgery?" - U.S. News and World Report
These days, 3-D printing can be used to make just about anything – from guns to eyeglasses.
In place of the ink used by their 2-D counterparts, 3-D printers take materials ranging from plastics and ceramics to metals and, layer by layer, create three-dimensional objects based on digital files. Also called additive manufacturing, the process supports a high degree of customization, making it particularly attractive for creating individualized solutions to problems – including those in health care.
One way the technology is being used in patient care is to prepare for complex surgeries – like removing a large brain tumor, where the margin for making accurate incisions is minimal. In such a case, a surgeon at The Ottawa Hospital in Ontario – which earlier this year launched the first hospital-based 3-D printing program in Canada – can request a 3-D model that would show the brain and the tumor, based on scans, to prepare for the surgery.
Such models are also used to discuss the procedure with patients in complex cases. “The patient is able to see exactly what the surgeon is going to do – how they’re going to make the incision, or the surgical cuts [and] what is going to come out,” says Dr. Adnan Sheikh, a radiologist and medical director of 3-D printing at The Ottawa Hospital. So that really helps the patient understand better what is going to happen with their care.
The same focus is also now being used to customize joint replacement surgeries – such as hip and knee procedures – for patients with significant anatomical abnormalities or deformities, explains Dr. Jason Koh, a spokesman for the American Academy of Orthopaedic Surgeons. An orthopedic surgeon who specializes in sports medicine, Koh is chairman of the orthopedic surgery at NorthShore University Health System in Evanston, Illinois.
Some patients have, for example, sustained a fracture; or it may be, he says, that “the normal geometry of the knee is distorted, or they have significant erosion of their bone so that the alignment of the knee is off.” While it’s common for cartilage in joints to be worn away with wear and tear – such as in the case of osteoarthritis – bone abnormalities or deformities can affect how well an implant may fit.
There are two ways that 3-D printing may help tackle the problem. First, many joint implant manufacturers now have 3-D printing capability and software. “So patients will get a pre-operative MRI or CT scan. That information is sent to the company, [which] then provides and makes the custom-made cutting guide to help assist in planning surgery for that patient,” Koh notes. The surgeon uses that sterilized custom, 3-D printed cutting guide in the operating room to assist in actually performing the surgical procedure.
That’s the most common way 3-D printing is used to customize joint replacement, he says. “The guides are used to help cut the bone, so that a pre-selected standard implant is able to fit better – in better alignment,” Koh says.
For all the hoopla surrounding 3-D printing in health care, a simple question remains: Will it improve patient outcomes?
In some instances, 3-D printing has proven all-important, as with an airway splint – which, in 2013, became the first 3-D printed medical implant used to save a life. “It’s a scaffold that goes on the outside of the trachea that’s designed to support a collapsing wind pipe,” explains Dr. Glenn Green, an associate professor of pediatric otolaryngology at the University of Michigan and pediatric otolaryngologist at U-M’s C.S Mott Children’s Hospital, who performed the 2013 procedure.
He's used the splint on a handful of patients since who – as with the first patient – also had severe tracheobronchomalacia, a rare condition that involves the collapsing of the windpipe. "The airway splints are extremely complex in the engineering that we’re able to offer and the level of customization; so we’re able to make things that grow, that open up over time as the child grows,” he says. “There’s a risk that it doesn’t open up the way that we’re hoping, and that it’d interfere with airway growth. But to date, things have looked good.”
The advantage of the technology, as it relates to improving care, isn't always so obvious. So experts say it’s important to discuss the perceived or expected benefits of using 3-D technology for any clinical purpose versus what’s known to date based on research, as well as risks and unknowns.
Theoretically, experts say that customization using 3-D printing with total joint replacement – whether for cutting guides or to customize the implant itself – might be expected to enhance surgery results and patient outcomes. But, in general, the vast majority of patients who undergo traditional total joint replacement do well in regards to reducing pain and improving range of motion and mobility. Because of that, research evaluating a large group of patients would likely be needed to home in on even small differences in improvement. “At this point in time, there’s no clear cut advantage … at least that I can see in the literature on total knee replacement,” Koh says, where 3-D printing technology is used versus the majority of joint replacement procedures where the technology isn’t used. The technology is still relatively new, he notes. So overall more research is needed to definitively determine if patient outcomes improve for hip, knee or other joint replacement surgeries when 3-D printing technologies are used. For now, at the very least, Koh points out that it’s safe to use the technology for total joint replacement – patients aren’t taking on added risk, compared with procedures where 3-D printing isn’t used.
“I don’t think that there’s conclusive evidence one way or another that customized instrumentation provides significant benefit,” he says. “But sometimes we have to see how things turn out over a period of several years with joint replacements,” Koh says – since most of the joint replacements work very well regardless of whether 3-D printing technology is involved.