SPENG Block Versus Suprascapular and Axillary Nerve Blocks for Pain After Shoulder Arthroscopy

This prospective, randomized, patient- and assessor-blinded, single-center non-inferiority trial will compare the analgesic efficacy of the Shoulder Posterior Pericapsular Nerve Group (SPENG) block with combined posterior suprascapular and axillary nerve blocks in adults undergoing elective shoulder arthroscopy under general anesthesia. Both groups will receive the same total volume and concentration of local anesthetic. The primary outcome will be the highest resting Numeric Rating Scale pain score recorded during the first 24 postoperative hours. Secondary outcomes will include block performance time, sensory block success in suprascapular and axillary nerve territories, opioid consumption, time to rescue analgesia, motor function, diaphragmatic function, postoperative recovery quality, patient satisfaction, and block-related complications.

Inclusion Criteria: * Age 18 to 70 years * American Society of Anesthesiologists (ASA) physical status I-III * Scheduled to undergo elective shoulder arthroscopy under general anesthesia * Able to understand the Numeric Rating Scale for pain assessment * Able and willing to provide written informed consent Exclusion Criteria: * Known allergy or hypersensitivity to local anesthetics used in the study * Infection at the planned block injection site * Coagulopathy or ongoing anticoagulant therapy that cannot be appropriately interrupted for peripheral nerve block * Pre-existing neurological deficit affecting the operative upper extremity * Moderate or severe pulmonary disease * Known diaphragmatic dysfunction * Chronic opioid use * Chronic pain syndrome * Body mass index greater than 35 kg/m² * Pregnancy or breastfeeding * Inability to understand or reliably report Numeric Rating Scale pain scores * Inadequate sonographic window preventing safe performance of the allocated block technique before randomization