I purchased the Arc4Health whilst suffering from a really bad back problem, that also caused nerve pains in my legs. I used it twice, sometimes three times a day for about 5 weeks, after which time the pain had completely gone. On two further occasions I have needed to use it, latterly with a torn knee cartilage. Again, it helped enormously. Now, I use it whenever I feel any twinges coming on, with excellent results. My brother is waiting for a hip replacement and my Arc has helped him with pain management.