Implants get ‘smart’ in orthopedics

Zimmer Biomet this summer announced a so-called “smart” knee implant—a first of its kind to be cleared by the Food and Drug Administration.

A little over a month later in October, orthopedic surgeons in New York City completed the first total knee replacement with the device—a knee implant with an embedded sensor that counts the steps a patient takes, their walking speed and range of motion, so that the surgeon can monitor their progress from afar.

It hints at a future where a sensor implanted in the human body can detect—and maybe even predict—a patient not recovering as expected.

“Data is key,” said Dr. Peter Sculco, an orthopedic surgeon specializing in hip and knee replacements at the Hospital for Special Surgery, and one of the surgeons who performed the surgery. “Now we have the ability to analyze big data in a much more rapid fashion.”

Zimmer Biomet’s smart knee product is just the start, analysts say.

It’s the first smart implant to be cleared by the FDA for a joint replacement surgery—but other medical devicemakers also have their eyes on the market.

“We’re just in the early innings of where this technology can go,” said Ryan Zimmerman, an analyst at BTIG who covers medical technology.

Devicemakers manufacturing implants for joint replacements want to continue to innovate and build on their products, as hospitals are exploring new ways to move more care to the home. An investment in smart implants also takes a page from developers of other medical technologies—like cardiac pacemakers and diabetes management tools—that have put data into the hands of patients, analysts say.

But medical device companies will have to prove the value of the innovative devices—and make sure they’re not adding unnecessary cost—to make a convincing pitch to customers.

“The potential is significant,” Zimmerman said, but it’ll take large research studies to prove the value to providers and payers.

A surgical first

As of mid-October, orthopedic surgeons at the Hospital for Special Surgery in New York City had performed one procedure with the smart implant, with plans to recruit others.

Today, post-operative monitoring for knee replacements tends to rely on patients reporting how they’re feeling, how much they’re walking and whether they can do daily activities.

“It’s very hard to get granular data,” Sculco said.

He’s interested in whether a smart knee can help with that, collecting daily data between a patient’s follow-up visits after the surgery.

Zimmer Biomet’s smart knee was a collaboration with Canary Medical, a company founded nearly a decade ago with a vision of putting sensors on medical implants.

The companies added a sensor from Canary Medical into an existing knee implant from Zimmer Biomet, called Persona, to create a new product named Persona IQ. Zimmer Biomet licensed the sensor from Canary Medical as part of an exclusive agreement to develop orthopedic implants together.

A sensor ideally will not only be able to collect more data points, but also more objective data, compared with the existing system that relies on patients reporting their outcomes.

The sensor collects and wirelessly transmits data to a small base station that a patient keeps in their home; from there, it’s shared with a platform that the surgeon reviews and then to a patient app. Data is collected multiple times a day for the first year after surgery and continues on a less frequent basis after that.

The battery that powers the device is supposed to last for at least 10 years, so it doesn’t have to be charged.

In theory, this data could one day help to identify patients who aren’t recovering as expected, so that surgeons can intervene early to make changes to physical therapy plans or medications.

“There’s a saying that hips are ‘wow’ and knees are ‘ow,’” said Dr. Fred Cushner, an orthopedic surgeon specializing in knee replacements at the Hospital for Special Surgery and a founder and chief medical officer at Canary Medical, citing a figure that up to 20% of knee replacement patients aren’t satisfied after their surgery.

Surgeons are still figuring out why that is—studying whether different strategies could be helpful when setting a knee replacement on patients with different body types, for example, he said.

During a knee replacement, an orthopedic surgeon replaces the surface of bones and cartilage in the knee with an artificial joint. The procedure, which was first performed in the 1960s, is designed to help patients who have arthritis or have suffered an injury, so they’re able to continue walking and doing other daily activities without pain.

Surgeons at the Hospital for Special Surgery are still figuring out what types of patients are the best fit to benefit from the smart implant. That’s something they’re planning to investigate through multiple research studies. For now, patient selection has centered on patients who are “tech-savvy” and interested in having access to this data, according to Sculco.

“This is uncharted territory,” Cushner said. “We’re going to learn from the data that we collect, and that’s going to guide us.”

No longer a ‘pipe dream’

Smart implants have been a topic of interest for years in orthopedics—but a push to connect data across the care continuum and advancements in sensor technology have made it a reality.

“Maybe 10 years ago, it was more of a pipe dream,” said Dr. Antonia Chen, director of research for arthroplasty services at Brigham and Women’s Hospital in Boston and program committee chair at the American Association of Hip and Knee Surgeons. “To actually have a commercialized product finally is very exciting. I think there will only be more out there.”

Ultimately, the vision behind smart implants is for devices to give orthopedic surgeons more information, Chen said. That could one day mean implants that detect problems like infections or if the implant itself is becoming loose—catching such problems at an earlier stage and, in some cases, potentially avoiding the need to re-operate on a patient.

The average re-operation rate for total knee replacement, in which a surgeon would replace some or all parts of the original implant, at one year post-surgery is 1.6%, according to a study published last year, each costing an estimated $20,000. Nearly half of readmissions within 90 days of a total knee replacement were associated with a re-operation within the first year.

Traditionally, it’s been hard to get sensors small enough to be integrated into the structure of an implant without significant modifications, said Eric Ledet, director of the health innovations incubator at the Center for Disability Services in Albany, New York, and a professor of biomedical engineering at Rensselaer Polytechnic Institute who studies orthopedics.

Knee implants have been refined and improved upon over the years. Manufacturers don’t want to develop a completely new and unproven device just to be more compatible with a sensor.

“It’s potentially taking several steps backwards with respect to safety and efficacy of the implant altogether if there are significant modifications that need to be made,” he said. “As technology for sensing has gotten more mature (and) more advanced, there are more opportunities now to integrate sensing technology into implants without having to modify the implant as much.”

The Persona IQ product adds a sensor from Canary Medical into a stem extension on the implant, which is usually a “solid hunk of metal,” said Dr. Bill Hunter, a founder and CEO of Canary Medical. It made sense for Zimmer Biomet and Canary Medical to start with a smart knee, since the sensor and electronics are roughly the size of a AAA battery—and a knee is big enough to accommodate that without changing the implant’s size.

The sensor doesn’t have software that needs to be updated, according to Hunter. The implant is mainly collecting and transmitting the data, while data analysis takes place outside the implant.

The push to get sensors into implants also coincides with a growing interest in outfitting patients with connected devices that move more care and monitoring into the home.

The COVID-19 crisis spurred new efforts to keep care out of the hospital—replacing some office visits with video visits and enlisting remote patient-monitoring tools to alert care teams when patients are deteriorating. Health systems and companies in recent months have formed coalitions to lobby for “hospital-at-home” programs.

The Centers for Medicare and Medicaid Services had already aligned some incentives for monitoring patients after joint replacement procedures with the Comprehensive Care for Joint Replacement Model, a bundled payment model that covers a patient’s episode of care from admission to 90 days after discharge—creating an opportunity for technologies that developers say can help surgeons improve outcomes.

CMS in recent years has also released codes to bill for remote patient monitoring, paving the way for clinicians to spend more time with this data.

“That did open, much more widely, the opportunity for physician offices and clinicians to be paid for another vector (of care),” after performing the actual surgery, said Matt Miksic, an analyst at Credit Suisse who covers medical supplies and devices, citing an estimate that surgeons could get reimbursed $200 per month per knee patient with remote patient-monitoring codes.

“I think we’re definitely going to start to see that more,” said Dr. Yale Fillingham, an orthopedic surgeon at Philadelphia-based Rothman Orthopaedic Institute who specializes in hip and knee replacements, of smart implants. “There’s lots of future applications to (smart implants) that could help us identify problems … before they would clinically present themselves.”

What’s the value proposition?

But for the smart implants market to take off, orthopedic devicemakers will have to pitch concrete benefits, showing that a sensor can really improve outcomes and cut costs by avoiding complications. Smart implants in orthopedics are “new territory,” Miksic said. The industry is still figuring out how the new market will play out.

“What’s the clinical and economic rationale?” Miksic said. “That’s the kind of equation I think that’s missing from where we are now.”

The cost of a total knee replacement varies, but the average cost in the U.S. is more than $37,000, according to an analysis of claims data from Guroo, a service of the Health Care Cost Institute. In addition to the procedure itself, there are costs associated with pre- and post-operative visits, as well as physical therapy after the surgery.

The procedure—a total knee replacement—is the same regardless of whether a surgeon is implanting a smart implant or not, so would follow the same reimbursement pathway from insurers, according to Liane Teplitsky, president for global robotics and technology and data solutions at Zimmer Biomet. After the procedure, surgeons can bill the patient’s insurance for payment related to time they spend on remote patient monitoring using data from the sensor.

Teplitsky declined to share additional details on the cost of the Persona IQ product.

At Hospital for Special Surgery, Cushner and Sculco said they expect data management and telehealth appointments spurred by the smart implant to be handled like other patient visits that would take place after a procedure. A patient may be responsible for deductibles and copays for those services, depending on their insurance provider.

Ideally, a smart implant could lead to cost savings, according to Canary Medical’s Hunter, if the sensor is proven to help identify patients who are doing poorly and can flag patients at risk for having poor outcomes. If a surgeon can intervene and adjust treatment plans proactively, that could reduce costs for the full episode of care, he said.

A smart implant could also shift more care to the home, if patients who are recovering well can do virtual check-ins, while patients who need support visit the office, according to Teplitsky.

But that hasn’t been proven yet.

Zimmer Biomet on a webpage warns that Persona IQ is designed to provide objective data—but that data isn’t intended to support clinical decision-making and hasn’t been shown to provide clinical benefit.

“I think that they’ve got a lot of great potential to help out patients,” Fillingham said. But, until they’ve demonstrated that, “is this going to add cost without additional value?”

If a smart implant is more expensive than a standard implant, it must create value that improves outcomes or drives down costs in other ways. As more smart implants hit the market, Fillingham said he’s interested in learning more about whether the products lead to earlier interventions for patients.

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Orthopedic surgeons like to see long-term data on the products they use, said Chen at Brigham and Women’s Hospital. She said she’s excited about the potential for a smart implant like Zimmer Biomet’s that would provide objective data on a patient’s step count and range of motion—but isn’t ready to use it yet.

One of the implants she often uses with patients has been on the market for 15 years—the other has been available for 30 years, she said.

She would want to see more evidence of how the smart implant performs before using it with her patients.

“The downside about a new implant or product every time is we don’t know how it’s going to fare in the long run,” she said. “If I see a benefit, I’d be happy to use it—but I’m not at that point yet.”