I have had all four of my horses acupunctured for some "thing" and it always worked --- except for the hock arthritis on my metabolic horse
It worked for about three days on his hock arthritis. I have him maxed out on the dosages of chondroitin/msm and hylarin/boswelia which do help immensely.
I have a very expensive infrared pad that helps in the winter but, geez, it has been so hot and humid, that I haven't used it on him since early May.
When the vet comes in September to do his six month physical for Equine Metabolic Syndrome, I am going to have him x-rayed so I know precisely what I am dealing with - truthfully I don't need those x-rays, but I need to see what's in there or isn't in there. My vet wants to avoid injections if at all possible, so I don't know know what the next step will be.
He is 24 and by the time he walks from his stall, thru the paddock to the main pasture he is moving pretty good but it breaks my heart that I really can't ride him too much because he is my Heart Horse and we've "been thru some times" in our 21 years together

He's the Fella in my avatar.
I am sure not saying to give up on the acupuncture because it may work wonders for your horse. If you can afford (money) to take the chance to see, I would take it in a heartbeat