The Duchess' mother and grandmother died of osteoporosis

Camilla's mother Rosalind Shand died of brittle bone disease and she is president of the National Osteoporosis Society (NOS).

The National Osteoporosis Foundation, its US sister charity, will honour the duchess with the Ethel LeFrak award.

She has sent a video message of thanks for the New York ceremony on 24 May.

The award is named after a New York socialite and philanthropist, Ethel LeFrak, who suffers from osteoporosis.

A Clarence House spokesman said: "The duchess is very honoured."

First visit

Executive director of the National Osteoporosis Foundation Judith Cranford said the award was being given for the first time.

"She (Camilla) has worked for several years and has seen the consequences of the disease within her own family," Ms Cranford said.

Camilla became the society's patron in 1997 and president in 2001.

Her mother died from osteoporosis in 1994 and in 2002 Camilla recounted the agonising ordeal she suffered in a speech at an international summit on the condition.

"The quality of her life became so dismal and her suffering so unbearable that she just gave up the fight and lost the will to live," Camilla said.