The 28-year-old Belgian was injured when he landed awkwardly after he appeared to be elbowed by Palace striker Connor Wickham.
Wickham has been charged with violent conduct by the Football Association.
Tottenham said: "Our medical staff will continue to monitor his progress during his rehabilitation to determine when he will be ready to return to training."
Chelsea goalkeeper Thibaut Courtois was out for three months earlier this season with a medial ligament injury.
Tottenham defender Jan Vertonghen damaged a medial knee ligament during Saturday's 3-1 win at Crystal Palace.