Erector Spinae Plane Block Vs. Superior Trunk Block for Postoperative Pain Control After Arthroscopic Shoulder Surgery: a Randomized Controlled Trial

Arthroscopic shoulder surgery can cause a substantial degree of postoperative pain that interferes with postoperative recovery. Adequate perioperative pain control can not only decrease duration of hospital length of stay and prevent unnecessary re-admission, but also facilitate postoperative rehabilitation and improve overall quality of life.

According to the 2019 PROSPECT guideline for rotator cuff repair surgery: systematic review and procedure-specific postoperative pain management recommendations, published on Anesthesia, postoperative pain can be controlled by systemic analgesics such as paracetamol and NSAIDS, regional analgesia, and opioids as rescue analgesia.

The current nerve block of choice is the interscalene brachial plexus block. It can provide adequate pain control, but is associated with several drawbacks including neurological injuries from direct nerve contact and pneumothorax, with the potential for phrenic nerve blockade and hemidiaphragmatic paresis raising the most concern. The superior trunk block, which is performed at where the C5 and C6 roots converge to form the superior trunk, was therefore developed, as it is located further away from the phrenic nerve. However, there are still considerable risks of phrenic nerve blockade, as well as nerve injury from direct contact and upper limb motor blockade.

The erector spinae plane block, first described by Forero et al. in 2016, involves the injection of local anaesthetic deep to the erector spinae muscles and has been widely studied for analgesia in thoracic surgery. It is a paraspinal fascial plane block and is assumed to share the same mechanism at different vertebral levels, including cervical and lumbar, to provide analgesia for a variety of different surgeries, including spine and breast surgeries. In recent years, erector spinae plane block performed at T2 level has also been employed for chronic shoulder pain and arthroscopic shoulder surgery perioperative pain management. Significant better perioperative pain control was achieved when compared with sham block using normal saline by Cftci et al. in 2021 and non inferior pain control was achieved when compared with peri-articular injection of local anesthetics by Shanthanna et al in 2022.

To date, there is no head to head trial comparing the effect of the established block of choice, interscalene brachial plexus block or superior trunk block, to the more novel T2 erector spinae plane block. We therefore designed this study to compare the use of superior trunk block and T2 erector spinae plane block in arthroscopic shoulder surgery with respect to their respective analgesic efficacy and undesired side effect of hemidiaphragm palsy. Primary outcomes of the study are postoperative pain score evaluated by the 100mm-visual analogue scale and morphine consumption, and diaphragm excursion assessed with ultrasonography, while the secondary outcomes include patient reported outcomes assessed by Quality of Recovery-15 (QOR-15) and Shoulder Pain and Disability Index (SPADI)