Pope Francis has canceled a scheduled Sunday visit to Florence and will not preside over Ash Wednesday commemorations next week because of what the Vatican described Friday as a flareup of “acute” knee pain.

The Vatican said the 85-year-old pope was canceling his participation in the events after his doctors prescribed a period of rest.

The pope has suffered for several weeks for what he has said was an inflamed ligament in his right knee.

Francis has long suffered from sciatica nerve pain that makes him walk with a pronounced limp, which has become more obvious in recent weeks.