Tapping on my spine?

Oncologists have been thumping my back and spine ever since my initial diagnosis five years ago. I was told that if I had a bone met, this would hurt so much I would jump off the table, presumably from the pain. Well, I have had bone mets for two years in many places in my spine and back. I still don't jump off the table. Either they don't tap hard enough or my mets are very small. The mets do ache from leaning back on hard chairs, etc. I don't think the tapping is that perfect a test.