The marathon world record holder has not run seriously since July 2012 when the injury ended her hopes of competing at the Olympics in London.
The Briton said her hopes of taking part in a 10km race this spring had been dashed due to a further setback.
At 39, time is running out for one of Britain's greatest distance runners to revive her career.
She told the BBC: "I'm very much in that limbo where I know and accept that realistically it may not be possible.
"But at the same time I have a little window of hope and I would rather be able to finish my career in a race, rather than a race I can't actually get to the start line of."
Radcliffe's career has been punctuated by triumph and disaster. Her peak came in 2002 and 2003, when she won Commonwealth and European titles, before twice breaking the marathon world records - her mark on 2:15.25 from London in 2003 still stands.
However, she failed to finish the Olympic marathon in Athens the following year, and was forced out of the race in Beijing four years later due to injury.
Radcliffe underwent foot surgery last August after being ruled out of London 2012, and in October she lost her National Lottery funding.
She said: "My target when I had my surgery was to run at the World Cross-Country Championship (which took place last Sunday), which I would have loved to have done.
"It was probably looking pretty bleak in December. I was really starting to severely worry if I was actually going to ever get back to running, even for pleasure.
"I've not even been able to run after the kids in the last few months, and you start to think about the first goal - to get back and be able to have a normal active life and then worry about if I can get back to competing."