The Apple Watch could be used for hip and knee patients

Hip and knee replacements may be the next health care frontier for the Apple Watch, now that it can monitor users' heart rates.

What's new: Reuters reports that 4 hospitals and a handful of other providers are working with Zimmer Biomet, a medical device company, to test an app that would transmit patients’ heart rate, steps taken and standing hours to their doctors.

• The project is focused on patients who are either waiting for or recovering from a hip or knee surgery — two of the most common procedures in the country.

Why it matters: There are plenty of concerns about just how effective Apple’s heart monitoring will be, and whether the risk of false warning signs outweighs the potential to catch legitimate irregularities.

• But if the information collected here is accurate and reliable, it will help doctors know whether their patients are following the physical therapy regimens they’re supposed to — which can help avoid complications that would land patients back in the hospital after their surgeries.