Cerebral mechanism of opposing needling for managing acute pain after unilateral total knee arthroplasty: study protocol for a randomized, sham-controlled clinical trial. - Zhao, Chi; Xu, Hui; A, Xinyu; Kang, Bingxin; Xie, Jun; Shen, Jun; Sun, Songtao; Zhong, Sheng; Gao, Chenxin; Xu, Xirui; Zhou, Youlong; Xiao, Lianbo (Trials, 2022)