The England international defender was brought to Goodison Park from Burnley in 2017 for £25million, but a horrible injury, which he played on through, meant he could not repliciate the form that got him the move.
Keane, in an interview with the 'Sunday Times' revealed that a two footed challenge by James Vaughan, in a League Cup game against Sunderland, could have seen his foot eventually amputated.
''I played on, but I knew something wasn't right,'' Keane said. ''I went in at half-time and my foot was aching but I didn't do anything about it and played the second half. When I took my boot off again there was blood everywhere. The skin was an inch apart, split away, a nasty gash.''
He received eight stitches at the time but the next day he was ''in absolute agony. I couldn't put any weight on it. I took ten minutes to get to the end of my bed.''
Keane carried on playing through the pain, with padding and a bigger boot on the affected foot, but was not able to reach the heights he had with Burnley in the tough circumstances.
After Everton's 5-2 loss to Arsenal his foot swelled up dramatically and he was rushed to hospital, with inflammation rising up his leg.
''If it had kept going up my leg that's when it really gets serious - they said if it had got much worse we might have been looking at losing the foot,'' Keane said.
The all action defender has found himself in the wars again this season, but after a concussion suffered against Bournemouth, the centre-back is now back to his best form and will hope to be pushing for a place in the England squad again.