Comparison of Postoperative Analgesic Effects of Interscalene and Shoulder Anterior Capsule Block in Arthroscopic Rotator Cuff Operations

Shoulder arthroscopy is one of the most frequently performed orthopedic procedures today. Although it is a minimally invasive procedure, it has been associated with severe postoperative shoulder pain and many techniques have been investigated for pain management. Today, anesthesiologists try to control postoperative pain well as one of the important components of enhanced recovery after surgery (ERAS), as this increases patient comfort and accelerates recovery. At the same time, opioids are tried to be avoided as much as possible while controlling pain due to their serious side effects. For these reasons, interscalene nerve block is frequently used in shoulder arthroscopy patients and provides highly effective and long-lasting postoperative analgesia. Interscalene block can also be used alone for surgical anesthesia in patients undergoing shoulder arthroscopic surgery and is accepted as the gold standard regional anesthesia technique. However, due to phrenic nerve involvement in interscalene block and loss of motor function in the upper extremity, new nerve blocks continue to be discovered for postoperative analgesia.

In 2020, Altinpulluk et al. showed that methylene blue applied to the deep subscapular muscle in a cadaver, between the humerus head and the area, stained the entire shoulder joint capsule and a certain amount of the axillary region, and they named this new block as pericapsular nerve block (PENG). Kupeli et al. and Ramudarai et al. applied the local anesthetic drug to the interfascial area between the deltoid muscle and the subscapular muscle and named this block as PENG block. The investigators think that this is the axillary nerve block with the Fajardo approach defined by Altınpulluk et al. Because in the cadaver study conducted by Gonzalez et al., it was shown that methylene blue applied between the deltoid muscle and the subscapular muscle did not spread to the pericapsular area. Nevertheless, postoperative analgesia was provided with the local anesthetic drug applied with both approaches and a motor protective effect was demonstrated. The injection made in both areas together can be called shoulder anterior capsule block (SHAC).

In our clinic, in our routine practice, the investigators perform the anesthesia procedure of patients who will undergo arthroscopic rotator cuff repair without general anesthesia, only with interscalene block. Since the SHAC block, which is a relatively new block mentioned above, does not provide sufficient surgical anesthesia on its own, patients must also be placed under general anesthesia. Our study aims to compare patients who have arthroscopic rotator cuff repair under general anesthesia with SHAC block and patients who have arthroscopic rotator cuff repair with interscalene block alone in terms of postoperative analgesia and motor-protective effects.

Materials and methods Ethics This double-blind, single-center, parallel-arm, randomized controlled study was approved by Hitit University Research Ethics Committee, numbered 2024-106. The study will be conducted at Amasya University Sabuncuoğlu Şerefeddin Education and Research Hospital.

Randomization and blinding Patients will be randomly assigned to two equal groups (ISC group or SHAC group) using a computer-assisted randomization method using the "Research Randomizer" program (www.randomizer.org), 46 patients in a 1:1 ratio. Due to the nature of the interventions, blinding will not be possible for the anesthesiologist administering the anesthesia. However, in order to minimize bias, the investigators responsible for the evaluation of postoperative recovery times, pain scores, and opioid-related side effects will be blinded to group assignment throughout the study.