actually, it can be done, without a broken back. Contortionists are quite flexible and able to twist themselves into various positions. Gymnasts, ballerinas are also quite flexible, not to mention the feline species itself. And since this is a fictitious character, with a fictitious expertise, she would be quite flexible and be able to contortion her body as needed. There is also a constant curve to her bend, without the radical 90 degree bend seen is some comics these days.
Thank you for your opinion however. Sometimes it is refreshing to hear someones actual opinion other than.."good job"