The centre-forward, who joined the Championship side last month on a three-month temporary deal, has had to undergo yet more surgery.
Everton’s Head Physiotherapist, Mick Rathbone, explained more: “James suffered a slight tear in his cartilage whilst playing for Derby a couple of weeks ago,” he told evertonfc.com.
“If there is anything positive at all about it, it’s that this is a brand new injury – it’s not a recurrence of anything he’s had before.”
Vaughan has managed just two appearances for The Rams and it remains to be seen whether or not he will be able to add to that tally during his loan spell.
“It’s a very minor tear and James has been to London this week to have the cartilage trimmed,” added Rathbone. “We hope that he won’t be out of action for too long.”