Rearing is a very dangerous problem and should be dealt with only by those who are capable and experienced enough to deal with it.
Some people revert to martingales and tie downs but a horse can still rear.
A rear is in the hindquarters. All the horse has to do is shift his weight back over his hindquarters and he can rear. If a cause cannot be established and corrected the horse should not be ridden. Hit and miss with a rearing horse is a form of riding roulette. It has a physical problem that causes it pain or fear severe enough to be violently evaded.