Hi,
I empathize with the trouble your father- in law is facing.
Wear and tear of the muscles is known to happen with advancing age. There seems to be a probability of
Osteoarthritis in him by most chances. He will need to take
Calcium supplements on a daily basis.
The outcome of spinal surgeries is not very good, better results are seen in up to 50% of cases.
Physiotherapy exercises would be best for him and slowly he can regain back his physical activities.
The treatment here is
rehabilitation and symptomatic management, rather than medications and surgery.
Regards,