I don't know if this applies but my friend's horse did (sometimes still does) this. We were told at the time he would never be fully "stumbleproof" because of the way he had grown. This was about a year ago when he was 4.5 years old.
Now he is tonnes better, it turns out that he had been broken to drive at 2... and had driven almost all his life until he was sold to my friend as ride and drive. This meant he almost always leaned into his work, but sharply and so far forwards he ended up tripping and falling. 6 months of lunge work twice a week put an end to that. He has also grown a lot and the vet now says the previous problem is almost non existent, he just came at the gangly and ridiculous stage!
thanks for replying , my horse is 16 had horrific injury as a baby to left foot in barbed wire and i think years of compensation have affected left leg , but at a loss what to do x
