Hi @contentandwell – RSD or CRPS (same thing) is considered a rare disease, so it’s not common to develop it. The most common trauma associated with it is a wrist fracture immobilized in a cast (although people do develop it following other injuries – mine was the wrist scenario, but with others it could be a leg injury). Still, it’s a rare disease. RSD/CRPS symptoms & signs are typically: pain out of proportion to the injury, that doesn’t go away as the injury heals, as well as hypersensitivity (some patients can’t tolerate a breeze on their skin), swelling, lack of mobility near the site of injury (my hand froze into a claw at first), muscle and bone loss, and noticeable differences between the affected limb and the healthy limb in skin color, temperature, sweating, hair and nails. If you are having persistent pain in the knee you had replaced, but it’s not severe and you don’t have some other symptoms, chances are it’s not RSD/CRPS. If you do have a lot of the symptoms, ask an orthopedic surgeon you trust (maybe not the one who did the knee replacement that hurts) – an ortho should know what to look for. Re: medications, so true, we all do react differently. Interesting that you had such different reactions to the same drugs! I hope your second knee replacement goes well.