Prolonged hammering and chiselling accelerated degenerative arthritis in the hands of Michelangelo Buonarroti, sculptor, painter and one of the greatest artists of all time. But the intense work probably helped him keep the use of his hands right up until he died. That is the conclusion of doctors writing in the Journal of the Royal Society of Medicine who analysed three portraits of the artist to reach their diagnosis.

All three paintings are of Michelangelo between the ages of 60 and 65 and show that the small joints of his left hand were affected by non-inflammatory degenerative changes that can be interpreted as osteoarthritis. In earlier portraits of the artist his hands appear with no signs of deformity.

Lead author Dr Davide Lazzeri, a specialist in plastic reconstructive and aesthetic surgery at the Villa Salaria Clinic, 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."

This, he goes onto explain, is because there are no signs of inflammation in the artist's hands and no evidence of any tophi, the small lumps of uric acid crystals that can form under the skin of people with gout.

According to letters written by Michelangelo his hand symptoms appeared later in life and in 1552, in a letter to his nephew, he wrote that writing gave him great discomfort. Despite this he continued to create one masterpiece after another and was seen hammering up to six days before his death in 1564, three weeks before his 89th birthday. By then Michelangelo was unable to write anymore and only signed his letters.

Dr Lazzeri 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."