Can The Inability To Straighten The Legs Be Cured?

Hi my name is Cortney. I was born with a defect called spina-bifida. I have a question about joints that could possibly be straightened out. I am supposed to have surgery on my legs so I can walk. But my legs cannot straighten out, and my hips are tight too. Preventing me from laying down straight on my back and stomach. Is this fixable?