More than one million knee and hip replacements occur annually in the US.
Apple and Zimmer Biomet want to sign up at least 10,000 people in the USA for the study.
More and more healthcare-related uses for the Apple Watch are emerging as Apple pushes further in the segment.
Zimmer is a USA -based company with operations in more 25 countries.
The mymobility app, along with the Apple Watch, wants to help connect patients and surgeons. They can also monitor the patient's activity levels in preparation for and recovering from surgery.
"We believe one of the best ways to empower consumers is by giving them the ability to use their health and activity information to improve their own care".
Four hospitals and more than a dozen other medical facilities in states including Massachusetts, California, Colorado and MI will receive stats including heart rate, steps taken and standing hours from patients waiting for or recovering from hip and knee replacement surgery.
Medical device company Zimmer Biomet and Apple are teaming up for a new app that will be combined with data tracked from the smartwatch to determine why some patients with knee and hip replacements recover faster than others. Called mymobility, the app will allow surgeons to send education and therapy reminders directly to patients. Considering the aging population, more people are expected to need knee and hip replacement surgeries in the coming years. In 2017, Apple partnered with Stanford Medicine to investigate how the Apple Watch's health features can be used to spot uneven heartbeats.
Apple is working hard to position the new Apple Watch Series 4 wearable as a state of the art health monitoring device.
Apple also announced that it will donate 1,000 Apple Watches for a study on binge eating that it is conducting in partnership with researchers at the University of North Carolina.