Garrett Richards has knee surgery

OAKLAND, Calif. -- Los Angeles Angels pitcher Garrett Richards underwent surgery Friday to repair the torn patellar tendon in his left knee.

Richards tweeted a picture of himself in a hospital bed before the surgery, then used social media to announce the procedure was finished.

The ace right-hander took to Twitter earlier in the day, too.

Richards was 13-4 with a 2.61 ERA this year before getting hurt Wednesday while covering first base during the Angels' 8-3 win over the Boston Red Sox. He is on crutches and might rejoin the club next week in Anaheim.

Angels manager Mike Scioscia said Richards' surgery "went as expected." He added that the timetable for Richards' recovery remains six to nine months.

Information from The Associated Press was used in this report.