Hello, I understand you have had sciatica of left leg for several years and had a decreased sensation in your left foot all along. Now you have developed foot swelling and your sensation in your sole has worsened that you started feeling as if you are walking on cotton wool and now xray shows Osteoarthritis of foot joints. This clearly shows that your back condition which can be either disc herniation (commonly known as slipped disc) or can be Lumbar canal Stenosis (Narrowing of canal in back from where your nerves come out in to the leg). The condition is now severe and is causing more pressure on your nerves of sole of foot. This needs urgent attention of a Spine or a Orthopaedic Surgeon who might advice you to go in for a MRI of the spine to find the cause if the nerve compression. Now second part of your question is about foot swelling. You seem to have only foot swelling and not foot pain. If you do not have pain, you mostly probably may not have any arthritis. Only very very rarely do patients with sciatica have foot osteoarthritis which is painless. So I may suggest you see a Specialist as I mentioned above, and get your spine tested which seems to be the major problem causing all the symptoms you face. I hope I have solved your question God Bless Regards Dr Merchant