Castro, 30, felt pain in his knee at the beginning of this month. The Twins hoped rest would alleviate the problem, but Castro landed on the disabled list on May 5 after being diagnosed with a tear in his right meniscus. Castro has been battling knee problems on and off for the past few seasons, Miller notes.
Castro hit .143/.257/.238 with a home run and three RBI in 74 plate appearances this season. Mitch Garver and Bobby Wilson will continue to handle catching duties while Castro is absent.