It is a big decision when you are faced with a major joint (shoulder, hip or knee) that hurts on a daily and nightly basis. It gets to the point where the pain and stiffness affects many of your daily decisions and can significantly erode your overall health. Health problems result not only from the lack of activity, but also from the effects of various over the counter treatments that can cause their own problems.
It is important that you exhaust all of the non-surgical means to alleviate your pain and improve function. I will go into more depth on non-surgical treatment options for arthritis in another segment.
Your surgeon cannot tell you if you should get surgery, but merely can tell you whether you are a candidate based upon your story, your examination, and your imaging (x-rays most commonly).
I find that many people decide to go forward at a point when they are self-medicating on a daily basis and/or they are losing sleep. Another turning point for many is when they are avoiding making plans to do things that involve activities or hobbies that are a source of happiness.
Another big factor is having trouble with basic necessities, such as getting in and out of the bathroom, or standing to cook food. Once you feel that your joint issues are causing you to stay in the house and avoid getting out to enjoy life, you may want to consider surgery.
For people who live alone, these issues are even more important and can cause safety concerns.
In the end, each person has a different point that becomes the deciding factor, and when it is time, you will know.