Casey may return for Irish's last two Premiership matches in April
London Irish's play-off hopes have been hit with the news that they will be without captain Bob Casey for most of the rest of the season.
BBC Radio Berkshire understands Casey had on operation on his right biceps, damaged against Bath in February.
Head coach Toby Booth said: "We're hoping for a speedy recovery because he's our captain and the talisman of the team.
"He had an operation last week and it's probably going to be six weeks or so."
The Exiles will be without Peter Hewat for a similar period, as he continues to recover from a medial ligament injury.