I was skeptical but desperate when I purchased this light. I knew my orthopedic surgeon had used something similar right after my surgery, so I decided to go with it. I was preparing to go on a trip that would involve a lot of walking but was still waking up every day with my knee so sore that I could barely stand, even several months after surgery. I used this consistently for maybe three days before I left, and my knee was dramatically better. I walked all over the place, and got up each morning with minimal problems. I haven't used the light on a regular basis since then, but it's two months later and I can still say this. I can't guarantee that this light was the key to feeling better, but I made more progress in a week than in four months without it. I've used it on other joints such as elbows, where I have arthritis pain, and it seems to help there as well. I just found out that I have a friend who's still struggling 6+ months after knee surgery, and I'm definitely going to recommend this.