@cak11555
I really don't have a definitive answer for you. There are so many medications used.
However, if I were to guess, I'd think it is probably something like is used when you have a baby and need a C-section.
I don't know specifically what frightens you. Is it the shot or hip replacement?
As I remember, after the initial prick of the needle, some sort of IV is used so that doctors can re-administer medication as needed without having to inject again.
Please know that I am NOT in the medical field in any way.
I share based on my own experiences and/or what others have said and/or research.
Hope this helps...
Ronnie (GRANDMAr)