Rhys Webb will undergo surgery over the coming weeks after the extent of the knee injury sustained on the final day of the season was confirmed.
The scrum-half left the field barely 15 minutes into last Friday night's defeat to Leinster at the RDS Showground and underwent an MRI scan earlier this week.
After consulting with specialists, Head Physio Chris Towers said:
"The MRI scan report has confirmed what we suspected, which is that Rhys has sustained an injury to the anterior cruciate ligament."
"He will undergo reconstructive surgery at a date to be confirmed over the next few weeks, and is looking at a lengthy period of rehab after that."