Santana, a former winner of the National League Cy Young Award, missed all of the 2011 season after suffering a similar injury in September 2010.
After reporting to spring training this year, Santana was diagnosed with weakness in his left shoulder. He has not appeared in a spring training game and New York General Manager Sandy Alderson said Thursday a decision would be made soon as to what course of action will be taken.
Santana was the Mets' opening day starter last year and on June 1 threw the first no-hitter in the history of the franchise. He did so while throwing a career-high 134 pitches.
In his next 10 starts Santana went 3-7 with an ERA of 8.27. The Mets eventually shut him down for the season in August.
Santana is in the final year of a 6-year, $137.5 million contract. He is scheduled to earn 25.5 million this year. Although there is a club option for the 2014 campaign in his contract, the Mets are not expected to exercise it.