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South Sydney Rabbitohs back-rower Angus Crichton has undergone surgery to amputate his finger in a bid to be fit for the start of the 2018 Telstra Premiership season.

Crichton ruptured a tendon in the middle finger of his left hand during his stint in the club's under-20s system and has been troubled by the injury since.

Rabbitohs general manager Shane Richardson confirmed the 21-year-old's surgery on Thursday.

"He's had it partially amputated. He's had a problem with that finger for three years now so he needed to do something about it," Richardson told NRL.com.

"He has had four operations and reconstructions on it and made the choice himself, in discussion with the medical team."

Richardson said the surgery would fast-track Crichton's return to the training paddock in January.

"Another reconstruction would have taken him between eight to 10 weeks to get over. This is going to take two weeks," he said.

"It just became so frustrating for him that every off-season he had to have a reconstruction, so he opted to partially amputate his finger. He had this option 12 months ago, and he chose not to do it.

"Now he has chosen to go down this path, a decision he made himself."

Crichton wrote in a column for Player's Voice earlier in the month on the intent to undergo the procedure after a sixth fusion in three years.

"I can't bend the finger, so it's like I'm constantly giving people the bird. If I clench my fist, my middle finger sticks out," Crichton said.

"The doctor said I could either cut it off halfway or fuse it. I've had it fused several times now because I keep breaking it.

"I've decided this is the last time I'm getting it fused. It's the fourth fusion that's broken and if it happens again I'm going to have it cut it in half, because I'm just over it."

The news comes as Crichton confirmed earlier in the week he will not be at the Rabbitohs in 2019.