Afraid of my dogs operation?

You are describing a luxating patella. The surgery is not that complicated for an experienced orthopedic surgeon. Any good vet will have run pre-anesthetic labwork on her before surgery to make sure her organ function is normal. She should have an IV catheter, IV fluids, pre-anesthetic pain medications, save IV anesthesia, intubated and maintained with gas anesthesia (halothane or isoflurane), and be hooked up to monitoring equipment such as heart monitor, blood pressure monitor and O2 monitor. Ask your vet if he/she supplies these things! She should also be send home with detailed instructions and pain medications. If your vet does all these things, she is having surgery done as safely as possible. No anesthetic procedure can ever be considered 100%safe but we can only do the best we can. Fortunately, in the hand of an experienced surgeon and staff fatalities are rare.