Demystifying the nipple: Madge goes for bust, bless her

First came Keira Knightley's breasts. Then Kim Kardashian's bottom. And now? Madonna's nipples.

There's no denying it. The last few weeks have seen the cup of celebrity naked flesh runneth over.

The Queen of Pop posed, topless, for a spread in this month' s issue of Interview magazine. Wearing a bustier and leather gloves, she reclines on a satin cushion, her hand to her forehead, her boobs bared.

It is styled as a romantic image - different from the black and white Knightley shot (which appeared in September in the same publication), in which she stared confidently down the camera, hands on hips.

And now Madonna is under fire for demystifying the nipple.

How dare she? At 56, no less. I'd wager you won't see a report today that doesn't mention her age alongside her cup size.

''Still got it," a few have already trilled.

Groan. They've utterly missed the point.

Madonna's decision to pose topless has nothing to do with showing-off her wrinkle-free cleavage - nor male titillation.

That she's an older woman is powerful, yes.

But it's clear this is far from a pop star trying to prove she's "still hot" in her 50s.

Madonna's age is just a convenient stick to beat her with. It's an easy reason for critics to cry ''put 'em away" without seeming sexist.

Of course, Madonna is no stranger to nudity. She's been taking her clothes off for decades. Her decision to pose for Interview is, then, perhaps less surprising than Knightley's. But it's no less powerful a statement. Here is a woman still at the top of her industry after almost 40 years. She's weathered numerous musical trends and managed to stay relevant. Why shouldn't she pose with her breasts exposed?

After all, she pretty much started it.

Indeed, just a couple of weeks ago, Madonna posted a censored topless picture of herself from the 1990s in response to the images of Kim Kardashian's oiled, nude backside in Paper magazine.

''It's confusing," she wrote. ''Nipples are considered forbidden and provocative but exposing your ass is not. #flummoxed' (sic)."

Madonna knew her latest photo shoot would shock. Topless pictures of famous women always have.

We might be used to seeing pictures of flat-chested models in fashion magazines (think Kate Moss on the beach, or backstage at a catwalk show).

But a model's body is a commodity - it is the vehicle she's using to sell products. For stars such as Madonna and Knightley, it is different. They are selling their own image, not someone else's. Choosing to bare their breasts is a feminist statement, not a requirement. They are saying: "Here I am. Take me, or leave me."

There's undeniably an element of desire wrapped up in all this. Knightley was criticised for being "unfeminine". Small boobs aren't traditionally seen as covetable. Neither are those of an older woman.

So, isn't it a blessing that we have these strong, famous women brave enough to turn unrealistic thinking on its head and show us the female body comes in many forms?

Madonna is flying in the face of what a naked woman ''should" look like. She's controlling her own image, just as she's always done.

Her attitude? Just because she's in her 50s, why should she hide away?

The sugary pink cardigan in the Interview picture says it all. ''I'm not ready to button up like a little old lady. Thanks all the same."