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  • Alex Hattaway

Wearables, smart implants show promise for clinical use

Although wearable technology has been used for research in orthopedics for several decades, its use for tracking patient outcomes has been in constant flux.

“Several years ago our institution started to use wearable technology to help patients with postoperative physical therapy, tracking their activity and sharing that information with the surgeon,” Claudette M. Lajam, MD, professor of orthopedic surgery at NYU Langone Grossman School of Medicine and NYU Langone Orthopedics, told Healio/Orthopedics Today. “This technology has been used over the years for patient care, but not consistently.”

Claudette M. Lajam, MD, said wearable and implantable patient-monitoring technology has the potential to give surgeons access to objective data that guide patients postoperative care and identify problems.

Source: NYU Langone Health

Physician interest in the use of wearable technology for tracking patient outcomes spiked somewhat during the COVID-19 pandemic, when physicians had to figure out the best way to monitor patients from a distance, according to Robert L. Barrack, MD, the Charles and Joanne Knight Distinguished Professor in the department of orthopedic surgery at Washington University School of Medicine.

“It was probably right around the start of COVID when we got involved with [wearable technology],” Barrack said. “Our main interest was in clinical research. Over the last half a dozen studies we have done, we monitored the patients with wearable devices. But, along the way, we have learned what data we can collect reliably and how we can use it to impact clinical care.”

Impact of wearables

One of the biggest impacts wearable technologies can have on patient care is by providing better communication between physicians and their patients, according to Neil V. Shah, MD, MS, a PGY-4 orthopedic surgery resident at the State University of New York (SUNY) Downstate Health Sciences University. By sending updates to a patient’s phone or smartwatch, physicians can remind patients when they have an appointment or direct them to taper down on pain medications, he said.

“Let’s say, for example, [the patient] had a ligament reconstruction in the knee, [the device can also communicate to the patient] at what point they should be transitioning from passive range of motion to start having active assisted range of motion,” Shah told Healio/Orthopedics Today.

Wearable technology also can be used as a substitute for home health care and physical therapy, Barrack said. By having patients download an app onto their smartphone that provides therapy exercises, Barrack said surgeons can then send reminders to the patient’s Fitbit (Fitbit) or iWatch (Apple) to do their exercises.

“Then all of their information would be transmitted to a computer dashboard so the surgeon could see that they were doing their exercises,” he said.

Use of a knee brace with sensors also can provide feedback to a patient’s smartphone and indicate whether the patient is correctly performing physical activity exercises while keeping track of the number of repetitions, according to Barrack.

“Patients like putting on the knee sleeve. It motivates them because they put it on before they do their exercises and it communicates with their smartphones and will tell them whether they are doing the exercise correctly,” Barrack told Healio/Orthopedics Today.

From wearables to implantables

Shah said a newer area that has gained some traction, but is still being explored, is the use of smart technology combined with an orthopedic implant to provide feedback to the surgeon.

“I think [smart implants are] more in the nascent period, but they certainly have potential to help assist clinical care down the road. Now it’s just a matter of identifying how best they can do that,” Shah said.

In total hip and knee arthroplasty, smart implants could be used to study prosthetic loosening and joint reaction forces, or the implants may be useful in spine surgery to measure force balances and force changes across the joints and vertebral bodies in the disc space, as well as during decompression performed for motion preservation, he said.

“The newer devices, such as the recent Total Posterior Spinal Arthroplasty System [Premia Spine] for decompression and replacement of bony/soft tissue, is a good example of a device that can benefit from the use of smart augmentation to be able to evaluate some of the static and dynamic forces across those joints and levels across which it is implanted to provide an objective and quantitative measure of both the theoretical benefits of preserving motion while also garnering stability,” Shah said.

Recently, the FDA granted de novo classification to the Persona IQ smart knee, which combines the Persona Personalized Knee (Zimmer Biomet) with the canturio te tibial extension sensor (Canary Medical), and is designed to measure and determine knee range of motion, step count, walking speed and other gait metrics, according to a press release from Zimmer Biomet.

“Right now, the focus is on gait parameters. So, you are getting step count, cadence, stride length and how many steps you are taking,” Fred D. Cushner, MD, knee surgeon at Hospital for Special Surgery and founder and chief surgical officer of Canary Medical, told Healio/Orthopedics Today.

Smartwatches, implants

The combination of smartwatches and smart implants used preoperatively and postoperatively may provide physicians with more information on patient well-being, according to sources who spoke with Healio/Orthopedics Today.

Lajam said wearable devices, such as smartwatches, can potentially be used before surgery to identify how much activity a patient performs and identify patients who would benefit from therapy and conditioning before surgery.

Smart implants can then provide continuous postoperative data and allow surgeons to take better care of their patients, according to Cushner.

“We have preoperative data with questionnaires and patient-reported knee scores. Intraoperatively, we have robotic data, how we put the knee in, and now we are collecting better postoperative data,” he said. “We will be able to correlate it all to see what is the best way [to treat patients] and even see if, perhaps, there is no one ‘sweet spot’ for everybody.”

Shah said adoption of wearable technology and smart orthopedic implants in the clinical setting may continue to be a challenge for physicians and institutions.

“I think our first example of this was the institution of the electronic medical record,” Shah said. “It has taken a long time for many hospital systems to roll over and roll into and transition toward these. So, that is a clear example of the massive hurdle that has to be overcome and the challenges that can come with [adoption of new technology].”

Adoption and compliance can also be an issue among patients, according to Cushner.

“In a study we did once with a smart fitness tracker, patients were eager to participate in the research effort. However, only one-third of the patients used the device the way they were supposed to,” Cushner said.

Inconsistency in technology

Regarding the technology itself, most wearable technology cannot detect the specific activity the patient is doing. These devices can detect that the patient — or the device — is moving, according to Lajam. She said different brands of wearable technology devices may monitor activity differently, so it is difficult to compare data across different devices. If surgeons want to compare outcomes between patients or even compare a single patient preoperatively vs. postoperatively, Lajam said the same technology would need to be used to improve consistency and accuracy.

“You cannot assume one device is measuring the same thing in the same way as the other,” Lajam said. “You cannot compare them against each other. If you are going to study your own outcomes, it needs to be done on the same device across your patients and across single patients over time because otherwise you do not know if your device is tracking the same activities in the same way.”

To solve this problem, Cushner said he and his colleagues are developing a wearable device to be worn preoperatively that is identical to the smart technology that is implanted intraoperatively.

“You give [the wearable device] to the patient 2 weeks before the surgery, you collect preoperative data in the exact same device and exact same fashion as the intraoperative [device], and then you can compare the two [postoperatively],” Cushner said.

Cost to track outcomes

Cost is another challenge. There is “not a significant amount of data available that demonstrate the cost efficacy or cost utility of incorporating” wearable technology and smart implants into clinical care, according to Shah.

“There are a lot of data showing these technologies help and that these technologies provide a clear benefit in various phases of care for the patients, but there is not that much high quality [data] that demonstrate how cost-effective it can be and how it can potentially reduce cost of office visits, rehabilitation visits and time spent on the phone,” Shah said.

Although CMS has billing codes for remote monitoring, “it would be hard for [physicians] to break even” using those codes, Barrack said.

“It would barely be enough to pay for the nursing or coordinating time to monitor it,” he said. “Somebody has to look at the output and act on the output, so, I think, right now it would be hard to justify the cost.”

Without being compensated for the additional work associated with wearable devices to track patient outcomes, Lajam said physicians would be disincentivized to take care of patients who have low health literacy or who cannot use technology correctly or at all.

“A surgeon might spend 10 hours helping a patient who has trouble using technology vs. 2 hours for someone who can use technology. Physicians are going to be discouraged from working with patients who need more time and help, especially when surgeons are not adequately compensated for this additional work,” Lajam said.

Patients at risk for complications

Follow-up visits can also consume a lot of resources, and although 80% of patients who undergo an orthopedic procedure do not need follow-up, Darryl D’Lima, MD, PhD, director of orthopedic research at the Shiley Center for Orthopaedic Research and Education at Scripps Clinic, said physicians still follow up with 100% of patients because they do not know which patients make up the 80% of patients who do not need extra care.

The use of wearable technology and smart implants may postoperatively identify which patients may be at higher risk for having a problem after surgery and require more follow-up, according to Cushner.

“By monitoring your patients, you can concentrate your resources, put more effort on those [patients who] are having a slow go at it and adjust the plan for people who do not need those resources,” Cushner said.

Data presented at the American Association of Hip and Knee Surgeons Annual Meeting showed patients randomly assigned to use the mymobility app (Zimmer Biomet) with an Apple Watch after total or partial knee arthroplasty were able to effectively guide rehabilitation, demonstrated similar outcomes to traditional care models and had a significant reduction in the number of outpatient physical therapy visits, as well as significantly fewer surgery-related ED visits.

“We’re encouraged to find that positive early results from our 90-day analysis were sustained at the 1-year follow-up and continue to reinforce that a mymobility-based remote care regimen could yield comparable patient outcomes and potentially require fewer health care resources than a traditional care model,” David A. Crawford, MD, one of the study’s lead investigators and a joint replacement specialist at JIS Orthopedics, said in a press release from Zimmer Biomet. “With smartphone-based remote care, patients tend to be more actively engaged in their recovery through access to real-time data to track their progress, and with the ability to communicate with their care teams more easily through messaging and virtual visits. In the study, these benefits may have contributed to lower utilization of health care resources, which can result in cost savings per episode of care.”

More research needed

In addition to more research needed on the cost benefit and cost utility of wearable technology, Shah said there is room to improve design of the technology “so that the size and cost is appropriate.”

D’Lima said it is important to continue to identify the electronic accuracy of the sensors and the accuracy of the sensors in diverse conditions.

“You have the patients being active and then, if it is a wearable, if it is under humid conditions or if the patient is sweating, that changes some of the accuracy of these wearables also,” D’Lima told Healio/Orthopedics Today.

While battery power is still an issue, researchers at SUNY Binghamton are proposing the use of energy harvesting to power orthopedic implants, he said.

“[Shahrzad Towfighian has] developed a unique type of energy harvester, called a triboelectric energy harvester, which uses frictional energy of the implant while the patient is walking and that powers the electronic,” D’Lima said.

Sensors in the spine, shoulder

In addition to sensors used in knee prostheses, researchers at the University of Pittsburgh Swanson School of Engineering are creating patient-specific 3D-printed smart metamaterial implants that double as sensors as a way to monitor spinal healing in patients undergoing spine fusion, according to a press release from the University of Pittsburgh.

“Smart implants can provide real-time biofeedback and offer many therapeutic and diagnostic benefits,” Amir H. Alavi, PhD, assistant professor of civil and environmental engineering and director of the Intelligent Structural Monitoring and Response Testing Laboratory, said in the release. “But it is challenging to integrate bulky circuits or power sources into the small area of implants. The solution is to use the implant matrix as an active sensing and energy harvesting medium. That is what we have been focused on.”

D’Lima and colleagues are also developing an electronic smart shoulder implant to monitor outcomes for total shoulder arthroplasty.

“The challenges we are facing are less on the technical side of things, because we do have mature electronics and a telemetry system, one that has worked in patients for over 14 years after implantation in knees,” D’Lima said. “It is more on the regulatory side of things.”

While the FDA at one time allowed implants and sensors to be used in patients under the custom implant regulation, D’Lima said FDA now classifies smart implants as electronic implants and requires these devices obtain investigational device exemption approval for use.

“That is an expensive undertaking and we do not have the in-house expertise to do that,” D’Lima said. “We have wanted to partner with an implant manufacturing company that is willing to bear the burden of getting FDA approval for implantation.”

Clinical use possible

However, once the FDA receives more data on and becomes comfortable with the use of smart orthopedic implants, the regulatory pathways will open up to include 510(k) approval, D’Lima said, noting the 510(k) regulatory approval process is “a significantly easier regulatory approval process.”

Despite the questions and concerns surrounding the use of wearable devices and smart implants in orthopedics, sources said there are signs that the use of this technology in the clinical setting has real potential.

“There is a lot of potential for this technology when you think about it. We typically have patients come back for visits and X-rays and we rely on them to tell us how they are doing along with our own evaluation of them when they come into the office,” Lajam said. “However, if you have good, objective information, it will help surgeons guide postoperative care and identify problems. The current regulatory environment for government and potentially other insurers is moving toward requiring outcome information from patients in order to avoid penalty payments to surgeons or hospitals. Access to data that are objective and do not require a patient to fill out surveys may be useful.”

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