The Barnsley-born Republic of Ireland international went against club wishes to accept the chance to join St Mirren for the second half of the season. A number of team-mates from the United Under-21 side he captained in the first half of the campaign have struggled for regular appearances during their loan moves into the senior game.
"Unfortunately, Oisin got bad news on the scan and is out for the season, which was a real blow for us. We had a few days to deal with that and let that sink in. All of a sudden, that's on top of Tomas Magnusson being out. We have to deal with that."