Eickhoff missed several starts last season dealing with a similar health issue.
Manager Gabe Kapler said Eickhoff injured himself throwing one of his final pitches in his most recent outing.
Eickhoff finished with a 4.71 ERA last year after making just 24 starts.
It's not clear yet what Kapler plans to do with the Phillies' rotation to start the season, though now it appears Vince Velasquez and Nick Pivetta are likely to secure spots as camp breaks. The final slot could go to Ben Lively, Mark Leiter Jr., or Zach Eflin.
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