Chen, L.; Duan, X.; Xing, F.; Liu, G.; Gong, M.; Li, L.; Chen, R.; Xiang, Z. Effects of Pulsed Electromagnetic Field Therapy on Pain, Stiffness and Physical Function in Patients With Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. JRM 2019, 51, 821-827.