The midfielder picked up the complaint during Saturday’s match against Blackpool. The game was only Ireland’s second appearance of the season - both substitutions - since he was loaned from Aston Villa in January.
Ireland was suffering from a knee problem when he arrived at St James’s Park, which was soon followed by a thigh injury in March. The 24-year-old had hoped that the loan move may become permanent, although his lack of availability for games has left him little chance to prove his worth to Alan Pardew.
Time spent visiting his partner Jessica Lawlor, who was involved in a car crash earlier in the month, has also hampered his chances of playing.