London Irish captain George Skivington is set to undergo shoulder surgery and is expected to be sidelined for four months.
The 33-year-old sustained the injury early in the season and has subsequently made just four Premiership appearances this term.
"George injured his shoulder at the start of the season and unfortunately has failed to respond to conservative treatment," a statement said.
"So, after further consultations with the appropriate specialists, the decision has been made to operate on George's shoulder.
"His rehabilitation post-surgery is likely to take about four months."
Lock Matt Symons will return to the side as captain for Saturday's meeting with Northampton Saints after missing the last three matches.