General manager Billy Eppler said before Wednesday’s game against Seattle that options to treat the injury will be decided on at a later date. Eppler said Richards would decide on "conservative care" or season-ending Tommy John surgery.
This is the third straight season that Richards has dealt with an arm injury. The right-hander had been limited to six starts each of the past two seasons. He missed most of 2016 due to an ulnar collateral ligament injury and had biceps nerve irritation last year.
"There is a scenario that could bring him back maybe the last couple of weeks, the last week, something like that," Eppler said.
Richards, who will become a free agent at the end of the season, is 5-4 with a 3.66 earned run average. He has made 16 starts this season, which is his most since 2015.
Richards made his second start on Tuesday since returning from the 10-day disabled list because of a left hamstring strain. He gave up three runs on four hits over 2 2/3 innings and left the game in the middle of an at-bat in the third inning against Seattle’s Nelson Cruz.