Apple Inc. has extended its reach again. This time, the tech giant and Zimmer Biomet Holdings Inc. have teamed up on a new app for the Apple Watch intended to connect patients undergoing knee and hip replacements with their surgical care teams. In the wake of this development, Zimmer Biomet, of Warsaw, Ind., this week reported the kickoff of the Mymobility clinical study, designed to assess the app's impact on outcomes and overall costs for joint replacement patients.