There is no way to tell how a cortisone shot will work for you until you actually try one. They work differently for different people. I have had several into the bottom of my feet for plantar fasciitis (now those DO hurt because of the location!) and they have worked amazingly well, full relief for 3+ months each time. Unfortunately, they do wear off and I ended up having surgery on both feet.
I've also had cortisone shots for sacroiliac joint inflammation and hip bursitis, and they have also worked, but not for as long as the foot ones did, and not as painful either.
There are risks with having too many cortisone shots, so most docs will only do a series of two of three injections and no more. You never know if it'll work for you unless you try. Depends on how much walking you'll be doing, if you can get relief with a brace or taping instead, etc.
Andi