Eastbourne Eagles rider Kim Nilsson now looks set to miss the start of the new Elite League season with the injury suffered in America.
The Swede suffered a fractured vertebra in his neck and back after a serious practice crash last month but seemed to be winning his fitness battle.
However, with his recovery set to take a few more weeks Eastbourne are evaluating their options with Timo Lahti an option to fill in if needs be.
Lahti has been spoken to about a possible replacement and Eagles' Co-promoter and team manager Trevor Geer says the team will not rush Nilsson back.
"We and Kim hope he will be fit to race again at the beginning of May," said Geer. "That is what he is aiming for but we must ensure he is fully fit before we bring him in.
"We have to think very carefully about all the options that are open to us and ensure we know the consequences of any course of action we take."