To ramble further...
Cats don't show pain. Assume a declawed cat is showing no behavioral issues. Or a behavioral problem is being blamed on something else. A cat parent has no way of knowing (or suspecting) the cat is in pain. No way of knowing if bone fragments were left behind, if there is any re-growth, etc. That cat will live his/her ENTIRE life in pain. Just because the cat parent doesn't know to what extent the cat is in pain, doesn't mean it isn't happening.