Mulder, 36, was attempting a comeback after a six-year absence. He signed a minor league contract with the Angels in January that included an invitation to the team's big league spring training camp.
Mulder took to Twitter after being injured:
I can handle this. But seeing my son in tears when he saw me in a boot and crutches and I told him I wasn't going to pitch. That was tough.
- Mark Mulder (@markmulder20) February 15, 2014
Mulder, in a text message to ESPN.com, said he doesn't know what his future holds right now.
"I really have no idea," he said.
Mulder said he hopes to meet with a surgeon on Monday or Tuesday.
"Once I do that, I'll maybe have a better idea of what's next besides rehab," he said in the text message.
Mulder is 103-60 with a 4.18 ERA in nine seasons with the Oakland Athletics and St. Louis Cardinals. He hasn't pitched since 2008 because of shoulder issues, and had been working as an analyst with ESPN since 2011.
Information from ESPN.com's Jerry Crasnick was used in this report.