Comparison of analgesic efficacy of shoulder block versus interscalene block for postoperative analgesia in arthroscopic shoulder surgeries: A randomised trial

Background and aims: Arthroscopic orthopaedic surgery may lead to significant postoperative pain. Interscalene block (ISB) is associated with undesirable effects like phrenic nerve palsy. Shoulder block (ShB) is a relatively recent diaphragm sparing alternative for analgesia in these cases.

Methods: This prospective randomised trial was conducted in 70 adult patients posted for arthroscopic Bankart repair surgery. Patients were randomly assigned into two groups: interscalene block [Group ISB (n = 35): 0.5% bupivacaine 10 ml] or shoulder block [Group ShB (n = 35): 0.5% bupivacaine (suprascapular block 10 ml and axillary block 10 ml)] using ultrasound and nerve stimulator. The primary aim of our study was to compare the ISB with ShB for visual analogue score (VAS) in recovery area (zero hour). Time for block performance, VAS, time to first rescue analgesia, total analgesic requirement, patient satisfaction and complications were recorded.

Results: VAS was significantly higher in ShB group at 2 and 4 h (P = 0.001 and 0.000) while it was significantly higher in ISB group at 12 h (P = 0.013). The time to first analgesic request was significantly prolonged in ISB group as compared to ShB group (8.22 h vs. 4.69 h; P = 0.002) but total analgesic requirement and patient satisfaction at 24 h were similar. Complications like dyspnoea, ptosis and motor weakness were seen only with ISB group.

Conclusion: Both ShB and ISB blocks have similar efficacy in terms of postoperative pain scores, cumulative analgesic requirements and patient satisfaction. However, considering the various undesirable effects associated with ISB, like phrenic nerve blockade, prolonged upper limb weakness and the occurrence of rebound pain, shoulder block may be preferred for arthroscopic shoulder surgeries.