Michelangelo suffered from arthritis as he aged, but addiction to work may have extended the use of his hands, an expert has claimed.

Three pictures of the great Renaissance sculptor and painter between the ages of 60 and 65 show evidence of osteoarthritis affecting the small joints of his left hand, research has shown.

In earlier portraits of the younger artist no signs of joint deformity can be seen.

Dr Davide Lazzeri, a plastic surgery specialist at the Villa Salaria Clinic in Rome, said: "It is clear from the literature that Michelangelo was afflicted by an illness involving his joints. In the past this has been attributed to gout, but our analysis shows this can be dismissed."

No signs of inflammation could be seen in Michelangelo's hands, and nor was there any evidence of tophi, the small lumps of uric acid crystals that form under the skin of people with gout.

Letters written by the artist suggest his hand symptoms appeared late in life. According to a letter written to his nephew in 1552, they caused him great discomfort.

Nevertheless he continued to create one masterpiece after another and was seen hammering only a few days before his death in 1564, three weeks before his 89th birthday.

By then, he was unable to write, and could only sign his letters.

Dr Lazzeri, whose findings appear in the Journal of the Royal Society of Medicine, said: "The diagnosis of osteoarthritis offers one plausible explanation for Michelangelo's loss of dexterity in old age and emphasises his triumph over infirmity as he persisted in his work until his last days.

"Indeed, the continuous and intense work could have helped Michelangelo to keep the use of his hands for as long as possible."