Your changes at L4, L5 and S1 discs would give symptoms in the legs and not particularly to your knees.
You need to go for an orthopedic examination to check for arthritis or any other problems in the knees. A detailed history would be invaluable, recollect any injuries, fall and finally X-ray and if required MRI will help in diagnosis.
I had the3 same problem, and still doe, I have had 2 total knee replacements on the same knee. I am in terrible pain. the Dr's threw up their hands and said I have never seen a knee like your and to be honest I dont know wjhat to do. So he put me on Oxycotin 40's 3 times a tday. The pain is unbearable. Come to find out, the ball was too big the first ime and the knee came loose, and the 2nd surgery, well they jusy dont know what to do, I am in BIGH trouble now, bwecause my insrnace is fixing to run out and I stioll am not fixed and Ineed some kiond of pain med for this. i need help. Does anyone out there readingmy probem have any ideas?
1) You need to understand the complications which took place if any during the surgery and the reason for 2 surgeries on the same knee. Discuss with your operating surgeon.
2) Latest MRI what does it show? Are all parameters undertaken during surgery have healed or not?
3) What about Physiotherapy? Without therapy you will never heal. You would need intense therapy till 12 weeks followed by some form of therapy after that.