I was in a minor car accident where my knee was injured. Found Penetrex and that with therapy seemed to heal my knee. A few years later, another accident totalled our car and both knees took a beating. Being older with A-Fib, the orthopedic surgeon did not recommend surgery so back to Penetrex. I have tried numerous meds, creams, lotions, and other OTC products. Always go back to Penetrex. Nothing has eased the constant pain, even sleeping at night, like Penetrex.