I went through all this for bone-on-bone osteoarthritis in the medial pocket. That's the side of your knee between your legs. they were bad enough that even I could look at the x-rays and see that there was something wrong. It was jarring when my doctor told me I would need knee replacement surgery. He always injected the gel or cortisone on the opposite side (for me, the outside). The gel worked, but he told me, and I knew, it was a stopgap measure. The relief would wear off in about 6 months (the exact amount of time my insurance company required me to wait between injections). I eventually got
partial knee replacements because only the medial compartment was bone-on-bone; the cartilage in the lateral compartment (the outside of my knee) was OK. It was probably the smartest medical decision I ever made. No more pain! My doctor (a different one than the one who diagnosed the problem) preferred to do one knee at a time rather than both in the same session. It is an overnight stay in the hospital. I was on the table for an hour and a half. You'll have physical therapy sessions until you can bend your knee back over 100 degrees. I must say it was disconcerting the first time I saw the post-surgery x-rays of these white plastic and titanium things in my legs. Mine don't set off airport metal detectors, BTW.