BUFFALO, N.Y. -- Former Blue Jays ace Ricky Romero will miss the remainder of the season following knee surgery.

Romero, who plays for the triple-A Buffalo Bisons, had surgery Tuesday on his left knee to clean out quadriceps tendon inflammation. He's expected to miss six months.

The 29-year-old lefty is 0-3 with a 5.50 earned-run average in nine starts with Buffalo this season.

Romero, drafted sixth overall by Toronto in 2005, was the Jays' ace in 2011 with a career-best 15-11 record and a 2.92 ERA. But his performance dropped off the next season to 9-14 and a 5.77 ERA.

Following that, Romero was sent down to the minors where he has struggled to regain his form.