Harford surgeon uses 3D technology for knee replacement

Surgeon John O'Hearn shows a traditional knee implant (left) as compared to the new, customized ConforMIS knee replacement (right), which uses 3D printing..
Surgeon John O'Hearn shows a traditional knee implant (left) as compared to the new, customized ConforMIS knee replacement (right), which uses 3D printing..(BRYNA ZUMER / Baltimore Sun)

A few years ago, when orthopedic surgeon John O'Hearn replaced a patient's knee, he would have been fumbling among seven to 10 trays to create an approximate rendering of the unique curves of the individual's bones.

Now O'Hearn can use one computer-generated plastic block made using 3D printing to match the patient's specific anatomy for a highly customized knee implant.


The longtime surgeon, based out of Forest Hill's Susquehanna Orthopedic Associates office, said he is the first doctor in Harford County to use the new ConforMIS knee implant.

According to the company, he is among the first surgeons in the U.S. to use the iTotal knee replacement system, which recently trademarked its "image-to-implant" technology.

"The thing that intrigued me is, they conform to the patient's anatomy," O'Hearn said about the ConforMIS system, explaining other knee implants are "off-the-rack," with a range of sizes trying to match the curvature of each knee.

The implant produced by the iTotal system "will fit whoever it's made for, nobody else," O'Hearn said.

To many in the medical community, the emergence of products like iTotal is unlikely to be a huge surprise, although O'Hearn remains unique among Harford's orthopedic doctors in using it.

Additive printing, better known as 3D printing, continues to pop up in cutting-edge ways for all kinds of uses, from toys made at the Abingdon Library's 3D "Innovation Lab" to the burgeoning concept of 3D-printed clothes.

ConforMIS, based in Bedford, Mass., launched the iTotal system in 2012. It may have hit a brief snag, as a voluntary recall was issued Aug. 31 for some serial numbers of the patient-specific instrumentation, with moisture reported on some of the instruments distributed between July 18 and Aug. 28, according to a press release.

Despite any setbacks, the world of 3D printing seems here to stay, and it's likely to keep expanding into newcorners of the medical world.


Richard Decker, executive director of the Havre de Grace-based Regional Additive Manufacturing Partnership of Maryland (RAMP-MD), hailed O'Hearn's initiative in venturing into the 3D field.

Decker has been spearheading a major push on the part of Harford legislators to make the county a leader in additive technology.

He noted RAMP-MD, along with the Greater Baltimore Business Council, will host a biomedical additive manufacturing conference in January.

Last year, legislators started working with Aberdeen Proving Ground's Edgewood Chemical Biological Center to create a regional 3D printing authority, hoping to capitalize on the Army post's resources.

The authority is branded RAMP-MD, Decker, a former ECBC director, said Tuesday.

"As a bi-laterial hip replacement patient as a result of a severe automobile accident myself, I am delighted with [O'Hearn's] success, and look forward to the day it is standard practice," Decker said via e-mail about the new knee replacement technology.


"I am sure the unique advantages of ensuring a unique one-of-a-kind custom fit under sterile conditions using this 'green' technology will result in higher functional success rates, comfort and longevity," Decker said.

'Nuanced evolution'

O'Hearn, for his part, had no hesitations about using the new technology.

The 68-year-old Havre de Grace resident, who has worked in the county since 1977, said he has been a leader in many ways over the years, such as doing endoscopic carpal tunnel surgery.

"I have always been attracted by technology," O'Hearn said, adding it is not for the sake of technology, but rather all in the name of giving patients a better experience.

For O'Hearn, it's been a natural progression from the days when doing knee replacement surgery meant having a patient spend a week in the hospital recovering.

The hospital stay later went down to perhaps three days, which O'Hearn said reduces infection from possible exposure to sick people.

"Infection, when it comes to a joint replacement, is a disaster," he said.

Preparing for recovery, he said, now starts before surgery, and physical therapy begins immediately after. That, combined with a multi-modal approach to pain management, allows patients to go home within a couple of hours of the surgery.

O'Hearn performs the surgery at his center on Bel Air's Thomas Street. He said new technology like the 3D-produced knee implant system has played a major part in facilitating patient recovery.

The actual implants from the ConforMIS system and other models are made of a metal alloy and polyethylene plastic.

Only the cutting block of the ConforMIS system is different; it's a plastic composite uniquely molded to each patient's specific knee structure.

The operation takes about an hour, and the cost of the iTotal system is roughly the same as other knee replacements, he said.

Nevertheless, with the customized implant, "I think the patient is getting the value for their dollar," he said.

The system does save about 15 to 20 minutes on each case by creating "a much more efficient process" that eliminates the surgeon having to fumble around for different instruments, he said.

"The shorter time that joint is open, the less potential for infection," he added.

O'Hearn said the new generation of medical products has greatly reduced the amount of wear on a knee implant, from about 1 millimeter per year to about 1/10 of a millimeter.

With 3D printing, O'Hearn said the medical field is on the edge of a new frontier of biologics.

"They can make everything with 3D printers," he said. "They are making bone replacements; they can 3D-print an ear."

"Orthopedics in general tends to be an early adopter of technology," he added. "It just seemed to me like a perfect application of that [3D] technology."

"It's all about efficiencies, so that patient basically gets more value for their money," he said. "There's lots of vendors out there of implants that are trying to customize it to a degree, but they are still putting out an off-the-shelf implant... This is the one, true customized fit, from beginning to end."