Yes her bone structure is phenomenal and especially for her age but she has admitted to having cosmetic procedures to maintain her looks, I'm not sure what those entail.
To me it looks like something has been done to her cheeks now, perhaps just carefully, sparsely applied filler?
Dear lord I can't stand Madonnas cheek implants, they're far to big and round for her face but I'm sure most surgeons would say she looks "healthy" now phfft...
Perhaps her main goal was to look younger when she got the cheek implants so angles and contours may not have even been discussed in her consultations. Also being so well known she might not have wanted to do something that could potentially drastically change the shape of her face.
I've said it before but the cheekbones Sailer gave to the red haired lady shown on his website are the closest I have seen to achieving modelesque cheek bones by artificial means. Aparently the lyophilized cartilage he uses transforms partly into the patients own bone which I find hard to believe.
Interestingly, it seems Mommaerts and two other surgeons used lyophilized cartilage to transform someones face into Micheal Jackson at his request.
http://www.ncbi.nlm.nih.gov/pubmed/11534446RE using bone for augmentation, someone asked this on realsef and the doctors said it could be done but questioned why when there are implants made of silicone, (I would have thought the obvious answer to this is because they
look like implants made of silicone!) I think they also said that a large amount of the bone graft would be absorbed.