The ground reaction foot orthosThe ground reaction foot orthosis (G.R.A.F.O) is a rigid molded splint that goes around the ankle and comes up the front of the leg over the top of the kneecap. This splint controls the foot position and causes pressure on the knee to straighten it.is (G.R.A.F.O) is a rigid molded splint that goes around the ankle and comes up the front of the leg over the top of the kneecap. This splint is used to control the foot position and cause pressure on the knee to straighten it.