Love Rugby League understands Green is unlikely to be back to full fitness before the end of the campaign, with seven games of the Middle 8s to come.
The front-rower picked up an injury in Hull KR‘s 20-24 loss to Leeds at home.
Wih Green off-contract at the end of the season, the forward may have played his last game for the Robins.
The 25-year old has made 19 appearances for Hull KR in 2016.
Green has spent his whole Super League career with the Robins, amassing 81 games after debuting in 2012.