Well, we aren’t sure what’s been tried so far. The usual course of action is a pharmalogical approach with antiinflammatories and analgesics (pain relievers). Finding the right drug (or combination of drugs) can take some time but is usually effective.
Other conservative measures may include steroid injections, bone stimulation therapy, and exercise. Yes, believe it or not, many studies have shown that exercise actually helps patients with severe knee pain from osteoarthritis.
For patients who do not want surgery, there are other alternative treatments such as hypnosis, acupuncture, and osteopathic or manual therapy. Other hands-on methods that have not been studied or proven effective but are still available include Reiki, BodyTalk, Therapeutic Touch, Healing Hands, and so on.
If nothing in that list appeals to you, there are some surgical options. The first is a neurotomy, which means to cut or destroy the sensory nerve that send pain messages from the skin, joint, and soft tissues to the brain.
Sometimes surgeons use high frequency radio waves to heat branches of the sensory nerves (hot enough to kill the cells). The procedure is called radiofrequency ablation or radiofrequency neurotomy. Usually a diagnostic nerve block is done to make sure that will work.
And a knee replacement is often an option. But perhaps you are too young for that just yet. For sure, you should get back with your surgeon and explore any and all options available.
Pain severe enough to wish someone would cut your leg off can usually be reduced if not eliminated. It may take some time and a trial-and-error approach but some combination of the suggestions made here should work.