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.