Kahlo was seriously hurt in a traffic accident when she was 18 years old and her injuries plagued her for her entire life.

At a stroke the incident ended her dreams of becoming a doctor and left her with debilitating pain and disability that continually worsened as she grew older.

Unlike previous treatments the aim was to actually fuse her spine together and was a much more drastic intervention.

Having consulted numerous doctors the surgery was deemed to be her best course of action but as time passed after the operation her condition continually worsened. Kahlo describes the procedure as "the beginning of the end."

In the self-portrait Kahlo appears thin and tired but also has an air of relaxation with her mouth close to smiling. Her hair, often used by Kahlo to express her emotions in her paintings, is thick and flowing and an exaggeration of how her hair was at the time.

This may have been to please her husband, Diego Rivera, who obsessed over her long hair.

At the bottom of the painting the scrolled parchment reads: "Here I painted myself, Frida Kahlo, with my reflection in the mirror. I am 37 years old and this is July, 1947. In Coyoacan, Mexico, the place where I was born". In reality her age was 40 years old.

The painting sold at auction in May 1991 at Christie's in New York and fetched a price of $1,650,000.

The 2003 film entitled "Frida" starred Salma Hayek playing the lead role of Kahlo. Hayek was a keen amateur artist and during filming and in her spare time she painted her own version of this work.