The condition, which is related to his age, has made it increasingly difficult for the 84-year-old Pontiff to walk -- in fact, it even prompted him to request the use of a wheeled platform devised for his predecessor, Pope John Paul II.
Andrea Tornielli, an Italian journalist with 'La Stampa' newspaper, has said that the Bavarian-born Pontiff has been diagnosed as having the degenerative disease caused by erosion of cartilage in joints over time, increasing friction and thus losing the capability to absorb shock.
The arthrosis has affected his knees, hips and ankles, Tornielli, who's considered one of the best connected and most authoritative Vatican observers, was quoted as saying.
Pope Benedict has often been seen dragging his right leg as he walks and publicly used a white cane during World Youth Day celebrations in Madrid in August. And, according to Tornielli, the Pope uses the walking stick even when moving around the papal apartments, the Daily Mail newspaper said.
However, Father Ian Ker, an Oxford priest and author, said it was unlikely that the Pope would quit simply because of problems with joints. "Arthrosis won't make any difference and at his age it is hardly surprising," Father Ker said.
Meanwhile, the Vatican has brushed aside the reports of arthrosis, saying for his age the Pope is in good health.
"He is currently studying the possibility of going to Mexico and Cuba in the Spring, which I think is rather more important. His state of health is fine and he is able to carry out his duties," Father Federico Lombardi, Vatican spokesperson, told The Daily Telegraph newspaper.