ANNAPOLIS — John “Bips” Egnor can simultaneously play a keyboard, two harmonicas — one on each side of his face — and a bass guitar with his feet. But after knee surgery a few months ago, playing a bass with his feet suddenly became more difficult.
Egnor, 67, had both knees replaced in January to straighten out his legs, which were not the same length. They had been shifting outwards for years after he had knee surgeries as a college football player to remove cartilage.
“After a while, I realized why I was playing wrong notes on the bass: My leg wasn’t cockeyed anymore; now it was straight, so I was having to make those adjustments,” said Egnor, of Pasadena. “But I played [Thursday night] at the Delaware Sports Hall of Fame and I had the stamina.”
Dr. James MacDonald, an orthopedic surgeon at the Anne Arundel Medical Center in Maryland, chose to replace both of Egnor’s knees using 3D imaging software to produce more accurate replacement parts for the knee out of metal polyethylene.
This sort of 3D imaging allows surgeons like MacDonald to be more precise. In the future, 3D printing could allow doctors to print replacement parts for knees, make cells to help heal wounds, or create blood vessels or even organs.
After MacDonald uses magnetic resonance imaging scans to produce a 3D image, he then sends to Smith & Nephew, a medical equipment manufacturer, which sculpts an implant custom to that particular knee.
“I know that his final result was actually better than if I had done the procedure in the standard way,” MacDonald said. “It was something that made a huge difference for this gentleman.”
These custom implants are then sent back to MacDonald, who can use them to replace a patient’s knees through an operation that is faster, more accurate and can cause less blood loss.
3D printing technology could allow medical manufacturers to create custom implants for patients like Egnor even quicker and cheaper.
Labs such as the Wake Forest Institute for Regenerative Medicine are working to make it possible to create parts for custom knee replacements, as well as other reconstructive procedures, with 3D printers. Researchers are able to do this in lab settings, but the technology is not ready for patient use.
Flat structures like skin are the easiest to 3D print, followed by blood vessels and other tubes, non-tubular organs, and, the most complex, solid organs like a liver or heart, said Anthony Atala, director of the institute.
Scientists at the institute have been able to 3D print all four tissue types and implant the first three in tests. They are working to make 3D-printed skin cells available to real patients.
“We’re making these always by hand, one at a time, and we wanted to come up with a system that would automate the process,” Atala said of the process of 3D printing with human cells.
Organovo is a company also working to design and build functional human tissues such as bone, blood vessels and even organs by 3D imaging with living cells, said spokesman Michael Renard.
The company has been able to build tissues — liver, some kidney, bone, lung tissue, blood vessel tissue, skin and muscle — that could be used as a form of therapy for patients; for instance, living cells could be printed onto a burn wound to help accelerate healing.
Although tissues are being built for experiments, including testing how diseases damage living tissues, Renard said he could not comment on when Organovo would be able to make these constructed tissues available for patients’ use.
“The skin is a big one; it’s a game changer in the long run in terms of the kind of quality of life people have, how we’ll be able to deal with people the loss of skin in a burn and tissue is a huge deal,” said Ivan George, director of the James and Sylvia Earl Simulation to Advance Innovation and Learning Center at Anne Arundel Medical Center.
George’s staff uses static 3D images to 3D print accurate physical models for planning purposes, he said. MacDonald and his colleague, Dr. Paul King, George said, are able to use this technology to create materials, such as knee replacements, that fit individual patients perfectly.
“I can recraft and retool a patient’s specific joint. That’s being done today,” George said. “Our surgeons do it here and they do it very effectively.”
Dr. Eduardo Rodriguez used 3D models to plan the historic face transplant he led while at the University of Maryland’s R. Adams Cowley Shock Trauma Center in 2012, George said.
George said Dr. Adrian Park, chairman and founder of the SAIL center, has successfully tested a scope — a camera on the end of a tube that is inserted into a patient’s abdomen during surgery — that is merged with the 3D image of an organ in real time to create a form of X-ray vision.
“What if I could see through the layers, see through the fat and actually know where those key structures are so I go straight to them with the greatest of safety and meticulous dissection,” Park said. He added that the University of Strasbourg in France is a leader in this area of augmented reality.
Static 3D modeling is being used regularly for work on joints, like the knee replacements MacDonald conducts.
But that modeling isn’t being used regularly for soft tissue such as organs or blood vessels yet, Park said, largely because they are more complicated because of their dynamic movement.
“The modeling issue for long bone stuff, for hard tissue like bone is going to be the vanguard of 3D printing and implantables,” Park said. “When we get to the point — and this will be worked on soon — where instead of having someone on dialysis or transplant a kidney — boy, what if we could actually print and grow a kidney and put that in instead.”
Despite successful applications of 3D imaging technology, such as Egnor’s knee replacements and Rodriguez’s face transplant, regular applications of 3D printing technology are not yet ready to be applied to patients.
Available technology also isn’t yet at a point at which it’s possible to 3D print knee replacements out of bone or metal, but 3D imaging has already begun to have real impacts on patients such as Egnor.
“I actually feel better now than I did before surgery; I really do and I didn’t think I would, I really didn’t,” Egnor said. “I feel like a million bucks right now.”