I had injections in both knees for about 7 years. Started off with cortisone, then Omnivisc, then Synvisc 1. They REALLY helped! I lived pain free for about 3 months after each injection, really with no limitations. Unfortunately, I developed psuedo sepsis which is a rare side effect, and couldn't get them any more. And, you can only have cortisone injections so many times, it can actually harm your cartilage. I ended up having bilateral total knee replacements right after turning 50 in 2014. Ice is your best friend! Try a polar ice unit, it's a little cooler thing that has a host and cuff attached. Fill with ice and a little water, wrap around your knee, elevate, and relax for about a half hour. The ice water circulates all around your knee, its heaven! I bought a splitter and 2nd cuff so I could do both knees at the same time.
My is injected with a gel. My kneecap is stapled together. It was fractured. So about every six to 12 months. I do it in 3 injections. They put my knee on a screen like a untrasounds.
Ask your doctor about injections with HYALURONIC ACID (an injectable jell) instead of cortisone injections.
My experience was the same the shots help for awhile, but I ended up getting a knee replacement. Wish you all the best.