"It's been a really frustrating couple of months for me with this ankle as nothing has seemed to go right," he wrote on social media.

"But hey, that's life. Glad to have got the op now and hopefully puts me on the right track back to recovery."

He added: "I'm gutted this probably means the end of my season but gives me an opportunity to come back fitter and stronger than ever."

Ulster have not commented officially on the extent of Stockdale's injury.

He will be unavailable for Ireland's Six Nations campaign, for which head coach Andy Farrell is set to name his squad this week.