Replying to Spinning help

The titile says it all, so every time i go to do a big spin off a rail like a 4 or 6 off. I wind up and hurl myself as fast as i can because i always feel like i wont every have a enough time to make the full spin. And my legs can't keep up and i twist my leg from over rotating to fast. then I'm out for like 2 weeks in pain. Not sure if anyone els has had this problem but i do. Is there any way to fix this i thought maybe a knee brace?