Hi Fran @sikocesca, I'm sorry to hear you are having numbness in the feet following your 2 knee replacement surgeries. I don't have any experience with low dose naltrexne (LDN) but there are a couple of discussion on LDN which you might want to read through to learn what other members have shared.

-- Success with low dose naltrexone for Autoimmune disorders: https://connect.mayoclinic.org/discussion/anyone-familiar-with-low-dose-naltrexone/
-- Anyone with experience using Low Dose Naltrexone?: https://connect.mayoclinic.org/discussion/anyone-with-experience-using-low-dose-naltrexone/

You mentioned leg length being different after your first knee replacement. You might like to read a post from one of our mentors @sueinmn in another discussion – https://connect.mayoclinic.org/comment/635851/. And here is an article on the subject -- Change in Limb Length After Total Knee Arthroplasty – NCBI: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4536512/

Have you ever had your gait checked or therapy to fix your gait?