The injury comes as Staines' premiership-winning former Penrith teammate Izack Tago prepares for a short stint on the sidelines with a minor pectoral strain.
Staines, who finished the match, is believed to have picked up his injury in a tackle during the second half of Sunday's 22-16 loss to the Sea Eagles at Campbelltown Stadium.
When his pain increased post-game, Staines notified club doctors and was admitted to hospital.
He remains there after undergoing surgery on Monday and will be replaced on the wing by veteran David Nofoaluma for this weekend's clash with reigning champions Penrith.
Tigers prop David Klemmer, known as one of the toughest customers in the NRL, was impressed by Staines' resolve to finish the contest.
"My respect for him has gone up another level," Klemmer said.
"Adrenalin got him through but as soon as the game stopped it must have just hit him like a ton of bricks.
"It's pretty amazing what he did. He was still taking carries and making tackles and putting them through it. It's a massive credit to him.
"I'm just glad that he's safe."
The injury is expected to rule Staines out for between eight and 12 weeks and is the latest blow to a side already missing five-eighth Adam Doueihi to a season-ending anterior cruciate ligament tear.
Premiership winner Staines has been a shrewd pick-up, covering fullback and wing, and was particularly impressive in the Tigers' improved showings in their most recent two matches.
"He's blown me off the park how consistent he is around his training, inside the gym and his footy as well," Klemmer said.
"I really rate him as a footy player. He's been great to play with and he's been great for this team.
"He's going to be a big loss."
Tago suffered his pectoral injury late in last week's 20-18 loss to South Sydney and has been replaced by veteran utility Tyrone Peachey for the clash with Wests Tigers.
While pectoral injuries usually come with long spells in the casualty ward, Tago will not require surgery and the Panthers are hopeful he is sidelined for less than a month.
