Noted orthopedic surgeon Dr. James Andrews performed the procedure.
“Dr. Andrews said it went very well,” agent Drew Rosenhaus tweeted.
Gronkowski tore both his ACL and MCL in a game against the Cleveland Browns on Dec. 8. Surgery on the ACL was delayed to allow time for the MCL to heal.
The surgery gives Gronkowski a 6 1/2-month window until the projected start of 2014 training camp in late July.