3-D technology provides custom fit, benefits in knee replacements

in Cedar Rapids on Monday, February 1, 2016.  (Cliff Jette/The Gazette)
in Cedar Rapids on Monday, February 1, 2016. (Cliff Jette/The Gazette)

CEDAR RAPIDS — The future has arrived, on bended knee. And Larry Johnson, 80, of Hiawatha, said yes — twice.

He’s so happy with the 3-D custom replacement in his left knee on Nov. 2 that he’s having his right knee rebuilt Feb. 25. His wife, Eleanore, 81, is happy with the conventional knee replacements she had in 2000 and 2005, but marvels at her husband’s faster recovery and improved range of motion — as well as how far technology has come in her lifetime.

Her grandmother was told to “take two aspirins and keep crocheting, keep moving, said Eleanore, who attributes her own bad knees to osteoarthritis and heredity.

Her husband, a retired Rockwell Collins manager, traces his knee woes to rheumatoid arthritis; unloading 100-pound bags of potatoes “constantly” in a grocery warehouse job at age 18; and years of volunteering to help friends with home concrete projects like pouring driveways, patios, garage floors and silo bases.

When nature and nurture finally left bone rubbing bone, Dr. Sandeep Munjal at Physicians’ Clinic of Iowa, 202 10th St. SE, deemed Johnson a good candidate for customized 3-D knee implants.

Among the criteria for any knee replacement, the patient should exhibit advanced arthritis, with bone touching the bone, and severe pain with daily activities, which no longer responds to other therapies, Munjal said.

To be a good candidate for a 3-D implant, the patient should have minimal physical deformities in the leg. Johnson’s leg bones are very straight from hip to ankle, with no bowing or knock-knee misalignments.


The ConforMIS 3-D implant, fabricated in Boston, is based on the patient’s CT scan to ensure a precise fit.

Cost to the patient and insurance coverage are the same for conventional and custom implants, said Munjal, 52, of Cedar Rapids, one of few physicians in the nation using this 3-D technology.

He’s done about 4,000 knee replacements over the past 20 years, and even though the emerging 3-D technology has been around for six or seven years, he’s been keeping an eye on it for about five years.

“I was waiting for the early results to come along before we started doing them,” he said.

He trained on the procedures in Florida, and has done about 30 to 40 3-D replacement surgeries in the past year.

“The surgery is no different from what I do every day,” he said. “The exposure is the same, the cuts are slightly different. It’s the frame of mind. I’ve done 4,000 knee replacements. You have to change a little bit in your thinking, your process — you have to evaluate it.

Whereas 85 percent to 90 percent of patients are said to be happy with a knee replacement, Munjal aims for the 95- to 100 percent satisfaction rating that Johnson has experienced.

“That 10 percent may not seem like a lot to you, but if I’m doing 400 (replacements) a year, that 10 percent is 40 patients a year,” Munjal said. “To increase that satisfaction to the next level is important to me and to the patient’s life.”


Johnson is thrilled with his range of motion, which aids in everyday movements like standing and climbing stairs.

“This knee replacement is custom-built for the patient, so the sizing and the fit (are) way more natural, as compared to what they call the ‘over-the-shelf’ knee,” Munjal said. “The motion is reproduced just like a natural knee. It is also bone-sparing — you don’t cut as much bone. You not only save the patient’s ligaments, but what you do is put it exactly where the natural knee belongs. So it moves better and patients feel more secure on that knee ... they feel more strong, more stable.”

The 3-D process takes six to eight weeks from shipping the patient’s CT scans to the manufacturer on the East Coast, until the box arrives, containing all the pieces and templates for making the required cuts in the bone. The surgery, itself, takes about an hour.

Patients are up and walking within hours after surgery and can typically stop using a cane after three or four weeks. The patients return for periodic checkups: after two weeks for staple removal, five weeks for X-rays and range of motion, then at three months, one year, and after that, every five years.

Physical therapy involves gait training and range of motion work for four to six weeks, depending on the patient’s progress. Fewer therapy sessions are needed with the 3-D implants, because range of motion is better, Munjal said.

Johnson continues to do some exercises on his own at home, especially since he’s preparing to have the other knee done.

Munjal sees 3-D technology as the wave of the future in other joint replacements, as well, including shoulders, hips and ankles, and partial replacements in the early stages of arthritis.

“To become the norm depends on surgeons’ preference and the industry,” Munjal said, “but I think it has a bright future.”

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