Inclusion Criteria:  Over 16 years old In normal conditions and mentally competent to participate in the study. Not having previous knee surgeries. In condition to complete the study questionnaires.  Exclusion Criteria:  Present some of the contraindications for a treatment with NESA XSIGNAL®: pacemakers, internal bleeding, do not apply electrodes on skin in poor condition, with ulcerations or wounds, acute febrile processes, acute thrombophlebitis and / or electricity phobia. Not having signed the informed consent. Urgent surgical interventions.