Jason Maguire will today undergo an operation in a bid to save his career.
Maguire finished second to Tony McCoy in the 2012-13 championship and with the perennial champion now retired, Donald McCain's stable jockey had hoped he could launch a realistic bid for the title.
But after having recovered from life-threatening injuries he sustained from a fall on the eve of the 2014 Cheltenham Festival, he suffered the misfortune of another serious back injury at Musselburgh in February.
"It's not an easy time," the Grand National-winning jockey told The Times.
"If it doesn't work, I'm not sure what more I can do to get back.
"It's a separate problem from the first one, lower down the vertebrae.
"I knew I was in trouble after a fall at Musselburgh.
"I'm staying positive but I don't know how I can come back if they can't get this right.
"With AP gone, I thought I had a great chance to be champion but it's not to be - at least for now."