3-D printing becoming more routine in knee replacements

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Photo courtesy of ConforMIS

A comparator is a used in the implant inspection process to ensure that each implant is manufactured the way it was designed. A magnified silhouette of the femoral implant is projected on a screen, and the dimensions are measured against the CAD design.

Thu, Jun 1, 2017 (2 a.m.)

Long receiving cortisone shots in his knee to relieve arthritis-related pain, 81-year-old Simon Pulitzer was left to rely on a cane to get around.

Pulitzer, who endured the strenuous process to replace his left knee more than a decade ago, knew it was time to undergo the surgery again — this time on his right knee. When he found out that new technology could refine the process, he listened.

“Before I had the procedure done, (the doctor) told me he was going to be a conformist,” Pulitzer said. “He said it would be a knee made especially for me.”

That new technology was 3-D-printed-assisted knee replacement. Henderson-based Dr. Robert Tait, among the first surgeons in the U.S. to use this technology for total knee replacements, has used it for about five years.

Pulitzer’s knee was scanned at a local imaging center, and the images were sent to ConforMIS in Boston, where his personalized knee replacement was created via 3-D printing. The printer creates a precise wax mold that helps form the metal components of the total knee. The implant is then based off the 3-D mold.

Click to enlarge photo

A Selective Laser Sintering machine is used to 3-D print instruments that the surgeon uses to make bone cuts and position the implant.

Simon Pulitzer, with his wife, Paula, recently received a 3-D-printed-assisted knee replacement.

Simon Pulitzer, with his wife, Paula, recently received a 3-D-printed-assisted knee replacement.

Dr. Robert Tait

Dr. Robert Tait

The tools used during the surgery, including the cutting board and surgical instruments, are 3-D printed as well, so that each tool is customized to the patient’s needs. The total knee implant can be done with 3-D printing using direct metal laser sintering and is FDA approved, but ConforMIS, which supplies Dr. Tait with the implant, has made a manufacturing decision not to do so at this time.

The typical knee replacement procedure features “off the shelf” components and come in a limited range of sizes that won’t necessarily fit everyone precisely.

With a total knee that is designed to fit the patient, surgeons may need to remove less bone, and recovery can be quicker and easier with less post-surgery pain with the 3-D-printed mold-assisted implant, a spokesman for Dr. Tait said.

“My recovery was a lot easier than when I had my first knee done 12 years ago,” Pulitzer said. “It was about a month shorter, and I didn’t use the pain pills as frequently as my first knee.”

Pulitzer worked with a physical therapist, aside whom he walked five days after the surgery in September. After three weeks, Pulitzer was completely mobile and continued his physical therapy five times a week.

Now eight months after the surgery, Pulitzer can go for three to four miles on the elliptical machine, and his cane has been relegated to the trunk of his car.

“I’m very happy with the results, I can tell you that,” he said.

Tait has performed more 4,000 knee replacements in his 22-year career. The approval rating with the traditional procedure was near 80 percent, he said. With the 3-D-assisted knee replacement, that rate has increased to almost 93 percent at his practice.

“That’s not perfect, but that’s a big leap for me to be able to do that,” he said.

The price associated with the 3-D process is higher compared to the conventional knee replacement surgery.

“The actual cost of making the implant is 10 times that of a conventional implant,” he said. “But there’s zero inventory costs. So, that’s what they can market themselves to the hospitals and come under the hospital's price caps.”

Now that knee replacements with 3-D technology are becoming more common, he said a lot of patients come into his office knowing about the procedure ahead of time.

Tait said he believes that 3-D knee replacement will become the norm soon.

“I really think that in five years this (3-D-printed knee implants) is the only thing that is going to be put in people,” he said.

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