What is the ruling for one unable to perform bowing (Ruku) and prostration (Sujud) in prayer?

Primary text

If one is incapable of performing bowing and prostration, one indicates them through pointing (Ima') in the same manner as pointing during a state of fear. The prostration must be indicated as lower than the bowing indication. If one is capable of prostration but incapable of bowing, they perform the bowing and indicate the prostration.