A Middlesbrough spokesman has confirmed that Julio Arca has departed the Championship club by mutual consent.
The 32-year-old's contract was due to expire at the end of the season, but the two parties have agreed to separate this week.
The spokesman told the Evening Gazette: "We've cancelled Julio's contract, which is due to expire this summer, by mutual consent to enable him to return to Argentina to further his rehabilitation."
Arca, who has made more than 150 appearances for the club, has been dogged by a host of injuries this season.