He explained:
"As a result of the procedure we expect that Rhys will be kept out of full contact for a period of 12 to 14 weeks.
"We don't see this impacting too much on his pre-season preparations in terms of his physical work, and as such, we are hopeful that he will be available for selection at the start of the season."
Meanwhile, tighthead Craig Cross has also undergone surgery, to deal with a cartilage issue in his right knee. Towers added:
"Craig will continue his rehab over the summer break, before undergoing what we expect will be a modified pre-season programme and we would expect that he will come good in time for the start of the season."