The Ospreys have lost a second player in a week to enforced retirment - 24-year-old Irish lock Conor McInerney this time the victim.
Flanker Ben Lewis, 25, announced his career's end on Monday, 28 March due to a neck injury.
A knee problem has ended McInerney's career after five appearances since joining from Leinster in 2009.
Ospreys physiotherapist Chris Towers said: "There are no options available that would allow Conor to continue."
Ex-Ireland Under 20 player McInerney said: Whilst this is extremely disappointing news for any player to hear, I feel very fortunate to have been given an opportunity to make a living in the sport that I love in the first place.
"The disappointment is lessened somewhat by the fact that it is the right decision for my body.
"I am very thankful for the support and belief the Ospreys have shown in me since I signed two years ago."