Greetings, sorry about the arthritis.
generally everyone speaks about pain killer affecting
liver or
kidney. Unless you confirm with blood tests about extent of damage or no damage at all to liver, do not assume yourself there is damage.
Liver is an organ which can clean itself, so it will protect on its own, just Give it correct food.
Next Steps
hire a physiotherapist as a trainer for your father and arthritis will be taken care of.
for body rejuvenation seek ayurveda, best way to recover
liver and whole body.
Health Tips
if Any concerns do let me know.