Injury to the anterior cruciate ligament (ACL) is very common among sports professionals and the general population [. Unlike other joint injuries, it is reversible, but it can damage adjacent tissues, particularly the meniscus, and catalyze knee osteoarthritis.

ACL injury produces instability, joint mechanical alteration, which can lead to degenerative joint diseases. The goal of treating the injury will be to prevent symptomatic instability, restore normal knee kinematics, and prevent degenerative joint disease .

Its usual treatment is surgical and therefore contributes to a significant cost for the health system, both for the surgeries themselves, and for the rehabilitation and subsequent recovery processes.

Within recovery therapies, in some cases, and given their popularity within the world of physiotherapy, electrotherapy techniques are proposed, primarily transcutaneous electrical nerve stimulation-type techniques with action on the muscular system and analgesia.

An early intervention with neuromuscular electrostimulation electrotherapy (NMES) combined with repeated exercises is effective for the recovery of strength and restoration of the biomechanical symmetry of the limb.

There is a diversity of opinions and disparate results regarding the use of this type of technique , in any case, it has been shown that electrical stimulation favors cell migration and joint tissue regeneration.](streamdown:incomplete-link)

The design of this study is a randomised, triple blind clinical trial with placebo control.

The general configuration of the study consists of capturing a group of patients treated with the same ACL surgical technique, operated on by the same surgeon, and including an additional treatment with the NESA XSIGNAL® device in a group of them.

For this, a double-blind capture system will be available (neither users nor specialists responsible for recovery will know which patients enter the complementary treatment) and two NESA XSIGNAL® devices operating double-blind (due to the imperceptivity of the stimulation performed, there will be a placebo machine and another that applies the treatment).

At the end of the study, the results obtained between the different groups of patients will be able to be compared; those additionally treated with a device, those treated with a placebo device and those in the standard rehabilitation procedure without a device.

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.

The intervention to which the subjects have been assigned, the specialist and the researcher who collects the information and performs the follow-ups will be blinded, using the simulated NESA XSIGNAL® device. Data analysis will also be performed in a blinded fashion.

Patients will be assigned to NESA XSIGNAL® device 1 or 2. These devices will be labeled "1" and "2" and only the manufacturer will know which is the real or the simulated one. In the same way, to avoid subjective comparisons of the participants, in the same room, device 1 and 2 at the same time will not be used.