Hypothesis: Percutaneous ambulatory carpal tunnel release offers similar outcomes to the open approach in the theatre.

Study design: Two-groups randomized single-blind interventional non-inferiority clinical trial.

Background: Carpal tunnel syndrome (CTS) is the most common compressive neuropathy in the upper limb, with a prevalence of around 1'14% and 14'4% of the population.

The clinical symptoms are usually pain, paresthesias and numbness on the sensitive distribution territory of the median nerve in the hand.

Conservative treatment is used for the mild cases, and surgery for the moderate and severe ones, or when the conservative treatment has failed.

Open carpal tunnel release is the gold standard surgery, with a short longitudinal volar approach that allows to visualize the complete division of the ligament.

Over the last few years, endoscopic techniques have been introduced, offering some advantages such as: lower postoperative pain, earlier return to work and less complications due to the wound. Despite this, it has not been popularised, probably, because it is a challenging and more expensive surgical procedure.

Based on the minimally invasive endoscopic approach, and with the aim of obtaining the same benefits, and avoid the complications of the open surgery, several devices have been developed to perform a percutaneous release.

Hypothesis: Percutaneous ambulatory carpal tunnel release offers similar outcomes to the open approach in the theatre.

Study design: Two-groups randomized single-blind interventional non-inferiority clinical trial.

Methods: Sixty patients reporting CTS symptoms, that are confirmed by clinical exam and nerve conduction studies, will be included. Participants will be randomized in two arms. Patients from one group will be operated with an open carpal tunnel release, in the theatre, with tourniquet, under local anesthesia and sedation, through a short longitudinal volar "classical" approach of the hand, that allows to visualize the complete division of the ligament. The other group will be operated with a percutaneous approach, ambulatory, with a short transverse volar approach, 1-2cm proximal to the wrist, under Wide Awake Local Anesthesia with No Tourniquet.

The main outcome measures will be the Boston Carpal Tunnel Questionnaire, Quick DASH questionnaire, Douleur Neuropathique 4 questions, Visual Numeric Scale and grip strength. The scales and questionnaires will be administrated to participants preoperative, 4 weeks and 24 weeks postoperative.

Inclusion Criteria:

• Over 18 years old.
• Positive electromyography, confirming carpal tunnel syndrome.
• Capable to understand risks and advantages of both procedures.
• Normal blood tests.

Exclusion Criteria:

• Previous carpal tunnel release in the same hand.
• Previous fracture or dislocation in the area around the forearm, wrist or hand.
• Signs or symptoms of infection.
• Psychiatric disorders.
• Antiplatelet or anticoagulant therapy, that cannot be suspended due to underlying pathology, and does not allow the surgery to be performed.
• Coagulation disorders, or any underlying pathology, with high risk of thrombosis or bleeding.