Hello dear You did not tell the cause of paralysis And in paralysis which surgeon would suggest you replacement baring in exceptional conditions. As post op rehabilitation requires good muscle conditioning for walking In paralysis it's not possible Any how's as far as other options are considered their are variety of other options depending upon the degree of osteoarthritis of knee Solutions available are corticosteroid shots to viscossuplementation shots and medicines to treat osteoporosis which also cause pain independently

I can prescribe vyou exercises online and doing that regularly decreases the joint stiffness He can not opt for surgery if he doesn't walk Does he walk? Consult me directly for more details