Hull FC will be without forwards Sam Moa and Danny Tickle for the rest of the season.
Moa, 26, has had surgery on a bicep injury while Tickle, 29, is to have a similar procedure at the weekend.
The Tongan Moa is out of contract at the end of the season while Tickle has made 18 Super League appearances for the Black and Whites this season.
Meanwhile, boss Peter Gentle confirmed he is interested in signing Castleford utility back Ryan McGoldrick.
He told BBC Radio Humberside: "I coached Ryan a long time ago back in Australia and I had a good relationship with him.
"It'd be a short-term deal until the end of the season and a chance for him to put himself in the shop window."
McGoldrick was made available for transfer by the Tigers on Wednesday.