Standing split, firefly : how to release and full extend the legs?

Hi

I am unable to stretch my leg up fullly in standing splits(I can only lift to hip height), straighten it in firefly or extend it to the side in one of the standing poses (I forget the name), and I am unsure what I need to do in terms of exercise or stretches to release the back of the thigh or glutes to extend the leg - there is no pain, the thigh just won’t release. Would PNF stretching be useful ?

One thing to consider is the structure of your hip joint itself. Yor femur and/or acetabulum could be shaped in such a way that your range is limited in that direction. I’m going to assume that the direction you are speaking of is hip extension; in that case the normal value for hip range of motion in extension is around 10 degrees.

http://www.julesmitchell.com/resistance-stretching-charlie-reid/