The New England Patriots have confirmed that they have placed defensive tackle on their injured reserve list.
The 32-year-old sustained a knee injury in his side's defeat to the Cincinnati Bengals in week five of the season.
Kelly has been trying to recover from the injury and returned to his side's practice on Wednesday after four weeks out.
However, after practising for two days, the former Oakland Raiders man missed the Patriots' training session on Friday and now has been ruled out for the season due to a re-occurrence of the injury.
The Patriots place him on injured reserve on Saturday and his place on the roster has been taken by offensive lineman Josh Kline.