Anterior Suprascapular Versus Interscalene Block for Postoperative Analgesia After Arthroscopic Shoulder Surgery in the Outpatient Setting

Inclusion Criteria: * Age \> 18 years. * ASA physical status I, II, or III. * Scheduled for unilateral shoulder orthopedic surgery in the outpatient/day surgery setting under general anesthesia. * Surgical procedures may include long head of biceps tenotomy, biceps anchor repair, Bankart procedure, rotator cuff repair with or without biological membrane augmentation, subacromial decompression, acromioplasty, or acromioclavicular stabilization. * Ability to understand the study procedures and provide written informed consent. Exclusion Criteria: * Contraindication to regional anesthesia, including allergy to local anesthetics, infection at the injection site, bleeding diathesis, or other contraindications according to applicable clinical practice recommendations. * Allergy to paracetamol or to any drug used in the multimodal rescue analgesic strategy. * Known neuropathy or sensory/motor deficit in the surgical area or in the territory of innervation of the study blocks. * History of psychiatric or behavioral disorders that may interfere with study participation or outcome assessment. * Severe obesity, defined as body mass index (BMI) \> 40 kg/m2. * Severe chronic obstructive pulmonary disease, GOLD stage III-IV. * Pregnancy. * Known phrenic nerve palsy associated with diaphragmatic paralysis. * Chronic opioid use during the previous 3 months. * Severe chronic pain during the previous 3 months, defined as NRS \> 4. * Non-adherence to the postoperative analgesic protocol.