Ten years ago, Nagaraj moved from his home village to a building site on the outskirts of Bangalore, where he works as a labourer earning the equivalent of $12 a week.

With his wife, Lavita, and three children, including their eldest son Bimesh, he lives in a cramped worker's shed next to the building site where he labours.

Life is hard for the family, as it is for millions of India's poor, but they at least have the basics of shelter and food.

However, with no social welfare safety net, any ill health will cripple the finances and prospects of this family that is already living below the poverty line.

Bimesh, a cheery, intelligent boy, has suffered from a congenital deformity affecting his spine since birth and now, aged 12, he has a noticeable curve in his back. As well as affecting his mobility, this has led to some social stigma.

If left untreated, he will suffer increasing health problems as he grows and his life expectancy will be no better than the four million other Indian children who will die before they reach the age of 20.

Once a year, the SPARSH hospital, which is part of the Narayana Hrudayalaya health city, runs a charitable programme known as Sparsh Vachana - 'the promise of a better life'. Under this scheme, the hospital provides free operations for up to 120 poor and underprivileged children. This year they are concentrating on orthopaedic cases.

The initial screening of the children takes place over three hectic days and 500 vie for the limited places available. With the odds stacked 5-1 against selection, it is a high stakes lottery in which Bimesh must participate.