It had been hoped that Whitehead, who has not featured in the first team since August, would this week complete a loan move to the Second Division Cobblers with a view to a permanent deal.
Whitehead is widely understood to be surplus to requirements at the Madejski Stadium and has been seeking a new club for a period of time now. However, a knee operation has not helped him in his quest. Indeed, a complication with the injured knee has prevented a deal from being pushed through.
Speaking to readingfc.co.uk, Whitehead, who was last season the club's first choice 'keeper, explained: "I was supposed to be going to Northampton on Thursday but I rung them up and told them I wasn't coming as my knee wasn't feeling right.
"I've had the knee problem for a while now, but I was getting nearer to full fitness and recently played two reserve games against Chelsea and West Ham.
"I basically came back too early from my knee operation and I won't be doing that again."
Whitehead will continue to train with the Royals but hopes to get a move sorted once he has regained full fitness. Should a move not happen now then the Halifax born shotstopper will likely leave the club for free in the Summer as his contract is up.
He added: "I need a fresh start to get my career up and running again. So I still hope to complete the loan move, with a view to a permanent move away from Reading."