Hi there ~
I understand your concerns. Unless your blood is specifically tested for substances of abuse (tox screen), your doctor will not know about the marijuana. Your metabolism
has nothing to do with marijuana clearance and it will show up if tested for about 2-5 months after stopping use depending on how much you were using. However you need to let them know about your dependence on marijuana if you plan on having a surgery for the arthritis
. It may be lethal in large doses to smoke marijuana and it might be as well to consult a psychiatrist
to kick the habit of smoking
marijuana and get back on track to the path of recovery.
I hope this helps. Take care and have a lovely day!