Unfortunately, for many people it will eventually get to the stage where there only thing that is going to help is a total knee replacement ( also called a total knee arthroplasty).
It is not uncommon for there to be a waiting period between when the decision is made and when the operation occurs. This may be a matter of weeks or, in the case of public health systems, many months.
Once you have agreed to a knee replacement your next question should be: What can I do between now and the surgery?
1) Remain as active as possible: Don't cease all painful activity while you wait. Continue as best you can despite the pain. Decreased activity can lead to loss of muscle strength and increased knee stiffness.
2) Work those quads: The stronger your quadriceps muscle, the easier it will be for you to recover from the surgery. Even if your wait is only a few weeks, improvements can be made.
3) Educate yourself about Deep Venous Thrombosis, a potential complication of surgery. Learn what you need to do to decrease your risk. This link goes to my article on DVT
4) Prepare your house: Remove trip hazards such as rugs. Remove clutter. Do any jobs that will be difficult after your operation.
5) Practice Crutches: If you have never used crutches before, consider learning how to uses them BEFORE your operation. Try stairs with crutches with and without a rail.
These are all simple, easy things to do and they can make your recovery much more pleasant. Don't waste the time before your operation - use it to your advantage.