I am a brown belt in Higashi karate and I'm being put up for my black belt grading this year. However, one of the things my coach keeps mentioning to me is my poor roundhouse kick. I have always had trouble getting enough height and my calf and thigh are never in line.

I have a distorted femur head and a slightly flattened socket so this is obviously causing some impingement, but I'm almost certain that the muscles are all tightened up because of this and with proper stretching I think I should be able to improve things.

So basically I'm wondering if anyone has any experience with this or any advice regarding stretching?