Just because we still do not fully understand how acupuncture works does not mean that it just doesn't work! It is a system of medicine, not a system of beliefs. Just like any other treatment, it will be effective for some and not as effective for others. However, the majority of people receive benefits from treatment (especially if they follow the recommended treatment plan!)
There are many medications and treatments in Western medicine that are not fully understood and require further inquiry. Science and medicine are evolving and our understanding of the world is constantly changing. Acupuncture has been used for thousands of years. Give it a try first instead of as a last resort. It's safe and helps with pain, and many other physical and mental/emotional conditions.