Anterior vs Posterior Approaches to Suprascapular Nerve Block in Arthroscopic Shoulder Surgery

Background Suprascapular nerve block (SSNB) can provide effective postoperative shoulder analgesia with less risk of phrenic nerve involvement than the interscalene brachial plexus block. We compared the analgesic efficacy and diaphragmatic effects of anterior and posterior SSNB using 5 mL of local anaesthetic in arthroscopic shoulder surgery. Methods This was a prospective, randomised, single-blind, two-parallel-group study of ASA I-III participants aged 18–80 years undergoing elective arthroscopic shoulder surgery recruited between July 2022 to June 2023. Participants underwent ultrasound-guided SSNB anterior and posterior approaches with 5 mL volume of 0.5% concentration bupivacaine. Randomisation was conducted 1:1 using a computer programme, and allocation was implemented using the sealed-envelope method. Participants and outcome assessors were blinded to group assignment. The primary outcome was the postoperative shoulder pain score measured on the Visual Analogue Scale (VAS) at 30 min, 4 h, 6 h, 12 h, and 24 h postoperatively. Secondary outcomes included opioid consumption, diaphragmatic thickening fraction, nausea, vomiting, and patient satisfaction. Results Sixty participants were randomised and analysed (30 per group). Postoperative pain (primary outcome) measured by VAS was lower in the anterior approach (GA) than the posterior approach (GP) at 30 min, 4 h, 6 h, and 12 h (p = 0.001, p = 0.001, p = 0.008, p = 0.001). Pain at 24 h was not statistically different after Bonferroni correction (α-adj = 0.01; p = 0.020). GA had lower cumulative opioid consumption at 30 min and 4 h (both p = 0.001). Opioid use was similar at 24 h (p = 0.140). Patient satisfaction was higher in GA (p = 0.001). PONV was lower in GA (p = 0.001). DTF did not differ between groups (p = 0.253). No serious adverse events related to the block occurred. One participant developed an urticarial rash from opioid administration, and one participant reported chest pain requiring further evaluation. Conclusions In arthroscopic shoulder surgery, the anterior approach may be a useful option for suprascapular nerve block, offering better early analgesia without an apparent effect on diaphragmatic function. Ethics approval and consent to participate: Ministry of Health Istanbul Medeniyet University Goztepe Training and Research Hospital Clinical Research Ethics Committee (Istanbul Medeniyet University, Istanbul, Turkey) (No: 2022/0155; Date: 16 March 2022) Levels of Evidence: LEVEL II, Prospective Comparative Study Trial registration: ClinicalTrials.gov, NCT05442814. Prospectively registered on 18 April 2022 (first posted on 1 July 2022; first participant enrolled on 11 July 2022).