Caldwell was hampered by the problem last month and could be sidelined until Boxing Day after lasting just 45 minutes of the recent away defeat at Newcastle.
The Scottish defender was already due to miss last weekend's draw with QPR through suspension and manager Roberto Martinez hopes the imminent return of Ivan Ramis will strengthen his patched up defence.
Ramis is rated as '50-50' to face Norwich on Saturday after a hamstring problem, while fellow centre-back Antolin Alcaraz is thought to be 10 days away from full fitness as he recovers from a groin injury.
"Caldwell is still in week one of a three-week recovery period," said the Spaniard.
"He missed the game against Reading (on November 24) as he was carrying a bit of a hamstring problem and that was accentuated in the Newcastle game.
"It will be between two or three weeks but he has recovered well and in the last couple of days he has been progressing.
"He won't be ready for Norwich but he won't be far away."