Hi
My mum suffers from arthritis through Lupus/steroids and finds it very hard to move. Most of the physical exercises are not possible for her. However, she does find that the mere act of focusing on practicing qigong breathing and doing the meditation exercises has an immediate physical effect - particularly on pain. Focusing on dantien energy and sword finger healing should also be very effective. Also even consciously adjusting and promoting better posture can help energy flow.
Your father might also like to try Level 1 Reiki, which also involves self healing through the laying on of hands. At the end of the day, when taken to its logical conclusion, all energy healing should really be possible through the mind alone. The mind in the end is the most powerful instrument of healing. This could be an opportunity for your father to see his current physical impairment as a real chance to develop the healing power of his mind. The physical should follow.
best of luck
Ingrid