Melanie Griffith fights a losing battle with the signs of ageing

But a few days later on a shopping trip, the focus moved down a few feet - to her wrinkly knees.

Although the actress does not turn 50 until August, the area exposed by her white cut-off jeans could have belonged to a woman of far more advanced years.

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Age before beauty: Actress Melanie Griffith shows off her baggy knees in Bermuda style shorts

Miss Griffith has in the past admitted having collagen injections in her mouth and is believed to have had a face lift.

It seems clear, however, that she has avoided the knife where her knees are concerned - taking the advice of her husband Antonio Banderas who insists that wrinkles are "beautiful".

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Bad knee day: Melanie Griffith wrinkled and saggy knees have not benefited from her rumoured splurge on cosmetic surgery

Harley Street plastic surgeon Apostolos Gaitanis said: "The knees are a huge problem area for women because the skin is thin and so ages badly. Factors like weight loss can also take their toll on the area.

"But a knee lift is a complicated procedure with a high level of scarring and so lots of women are reluctant to go under the knife."

He explained how a patient can have the whole leg lifted, leaving scars on the less obvious inner thigh area.

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Premature signs of ageing: The 49-year old has been waging a battle against losing her good looks

"This procedure is normally carried out on those who have lost lots of weight, and is a dramatic step to take.

"The other option is sucking fat out from around the knees, called liposculpture. There is little scarring with this, but it doesn't remove the wrinkled skin."

He added: "Most women of that age will find covering up when they go out an easier option."

Other stars, however, have taken steps to combat the problem of ageing knees.

Actress Demi Moore, 44, reportedly had a £5,000 knee lift in 2004 because they looked so out of place with the rest of her toned body.

And 39-year-old Nicole Kidman prompted speculation that she had tried liposculpture when she was spotted sporting sticking plasters around her knees while on holiday a little over two years ago.

After this treatment, a patient will wear plasters and support stockings while the skin recovers.