Fire acupuncture for mild to moderate knee osteoarthritis: a protocol for a randomized controlled pilot trial oleh Yuan-Bo Fu, Bin Li, San-Feng Sun, Hui-Lin Liu, Xin Wang, Shao-Song Wang, Fan Zhang, Xin Du, Du-Juan Ge, Lei Shang, Rui-Li Liang, Li-Na Wang, Fang Yuan, Jing-Qing Sun, Jun-Wei Chen