Effectiveness of Field Block Compared With Interscalene Block in Shoulder Surgery

Regional anesthesia is widely used for shoulder surgery, most commonly with an interscalene brachial plexus block (ISB). While ISB provides effective pain relief, it is associated with side effects such as hemidiaphragmatic paralysis, breathing difficulties, Horner's syndrome, nerve injury, and rebound pain. These risks limit its use in patients with respiratory conditions, obesity, or other contraindications. A shoulder field block (FB) is a newer approach that targets the suprascapular, axillary, and lateral pectoral nerves, which supply most of the sensation to the shoulder joint. Unlike ISB, the field block does not affect the phrenic nerve, making it a potentially safer option. Cadaveric and early clinical studies suggest that field blocks may provide effective pain relief with fewer complications, but direct comparisons with ISB in surgical patients are limited. This randomized controlled trial will enroll 64 adult patients undergoing arthroscopic or open shoulder surgery. Patients will be randomized into two groups: Field Block Group: Local anesthesia field block performed by an orthopedic surgeon using anatomical landmarks. Interscalene Block Group: Standard interscalene block performed by an anesthesiologist. The primary outcome will be postoperative pain intensity measured by a numerical rating scale (0-10) at multiple time points during the first 48 hours. Secondary outcomes include patient satisfaction, hospital length of stay, opioid consumption, complications, and unplanned medical visits due to pain. The study hypothesis is that a shoulder field block will provide pain relief that is non-inferior to an interscalene block, while reducing side effects and improving patient satisfaction. If effective, this technique could offer a practical alternative that can be safely performed by orthopedic surgeons, expanding anesthesia options for shoulder surgery patients.