Knees that talk; phones that detect strokes; tea and longevity

Medical Minutes

Hold on, I am getting a message from my knee

It is now possible to receive data from your knee about how it is healing. Knee replacements are getting smarter and may improve outcomes, thanks to a new joint component that securely tracks and transmits knee motion data. Physicians are using the data to optimize patient monitoring and recovery.

The new component is called the Persona IQ Smart Knee implant. It includes a 10-year battery and sensors that constantly capture long-term postoperative data on cadence (steps per minute) and average walking speed. It also transmits data on a person’s stride length, range of motion, distance traveled, and step count.

The data collected by the sensors are transmitted daily to the patient’s home base station and analyzed overnight. The information is made available to an individual in a phone app, which organizes and displays the data. In addition to graphs and charts that display collected data over time, the app includes patient education materials, pre-operative and post-operative exercises, and messaging capabilities.

“Physicians can use the collected data to monitor how patients are doing after their knee replacement, as well as for research that will improve future knee replacement procedures. Patients can also use the app to track their progress since their surgery,” said orthopedic surgeon Dr. Yair Kissin, who is with Hackensack University Medical Center in New Jersey.


Tea drinking associated with a long life

Tea is one of the most consumed beverages worldwide. Previous research has suggested an association between tea consumption and lower mortality risk in populations where green tea is the most common type of tea. In contrast, published studies in populations where black tea drinking is more common are limited with inconsistent findings. Now, a new prospective study found that drinking black tea may be associated with a lower mortality risk. The risk was lowest among persons drinking two or more cups of tea per day.

The findings, which were published in Annals of Internal Medicine, are highly relevant because the study also looked at whether the associations differ by use of common tea additives like milk and sugar, tea temperature, and genetic variants affecting the rate at which people metabolize caffeine.

Researchers from the National Institutes of Health conducted the study to evaluate the associations of tea drinking with death rates using data from the U.K. Biobank, where black tea drinking is common. The U.K. Biobank includes data on half a million men and women, age 40 to 69 years, who completed a baseline questionnaire between 2006 and 2010.

Among these participants, 85% reported regularly drinking tea and 89% reported drinking black tea. Relative to tea nondrinkers, participants who reported drinking two or more cups each day had 9% to 13% lower risk for mortality.

The associations were observed regardless of whether participants also drank coffee, added milk or sugar to their tea, their preferred tea temperature, or genetic variants related to caffeine metabolism. According to the authors, their findings suggest that tea, even at higher levels of intake, can be part of a healthy diet.


Smartphone may help prevent strokes

In a small study in Taiwan, motion analysis of video recorded on a smartphone accurately identified narrowed neck arteries in adults, which are a risk factor for strokes. It is hoped that this type of technology may be an early screening tool for detecting narrowed arteries in the neck.

Fatty deposits (plaque) can accumulate in arteries, causing them to narrow (stenosis). Narrowed arteries in the carotid artery in the neck can cause an ischemic stroke, which occurs when a vessel that supplies blood to the brain is obstructed by a clot. Nearly 87% of all strokes are ischemic strokes.

“Between 2% and 5% of strokes each year occur in people with no symptoms, so better and earlier detection of stroke risk is needed,” said lead study author Dr. Hsien-Li Kao, who is an interventional cardiologist at National Taiwan University Hospital in Taipei, Taiwan. “This was an exciting ‘eureka’ moment for us,” Dr. Kao said.

The current approach involves diagnostic methods employing ultrasound, CT scans and MRI imaging equipment and personnel.

“Analysis of video recorded on a smartphone is non-invasive and easy to perform, so it may provide an opportunity to increase screening,” said Dr. Kao.

The researchers conducted the study between 2016 and 2019, using motion magnification and pixel analysis to detect the minute changes in pulse characteristics on the skin’s surface captured in a smartphone video recording. A group of 202 adults, average age of 68 years and 79% men, who received care at a single hospital participated in the study. Among the participants, 54% had significant carotid artery stenosis, meaning they had at least 50% blockage that was previously diagnosed by ultrasound, while 46% did not have significant stenosis.

Recordings were captured with participants laying on their back, with their head tilted back in a custom-made box that minimized outside movement. An Apple iPhone 6 was mounted to the box to capture a 30-second video recording of the person’s neck. The older generation phone was used, as researchers believed it would be more common to the average user.

The researchers found that the video motion analysis algorithm had an 87% accuracy rate of detecting stenosis in the group known to have carotid artery stenosis. All study participants also had standard Doppler ultrasound testing to confirm narrowing in their arteries and to validate the estimates from the video motion analysis.

“More research is needed to determine whether video recorded on smartphones is a promising approach to help expedite and increase stroke screening,” Dr. Kao said. “Carotid artery stenosis is silent until a stroke happens. With this method, clinicians may be able to record a video of the patient’s neck with a smartphone, upload the videos for analysis and receive a report within five minutes. The early detection of carotid artery stenosis may improve patient outcomes.”

John Schieszer is an award-winning national journalist and radio and podcast broadcaster of The Medical Minute. He can be reached at

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John Schieszer is an award-winning national journalist and radio and podcast broadcaster of The Medical Minute.

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