Interscalene brachial plexus block is superior to subacromial bursa block after arthroscopic shoulder surgery

Background: Arthroscopic shoulder surgery is often associated with severe postoperative pain. The results concerning subacromial bursa blockade (SUB) as a method of pain relief have been contradictory. We hypothesized that a SUB and interscalene brachial plexus block (ISB) would similarly reduce early postoperative pain and the need for oxycodone as compared to placebo (PLA). Methods: Forty-five patients scheduled for arthroscopic shoulder surgery were enrolled in this randomised, prospective study. The ISB and SUB blockades were performed with 15 ml of ropivacaine (5 mg/ml). In the PLA group, 15 ml of 0.9% saline was injected into the subacromial bursa. All patients received general anaesthesia. Results: The mean intravenously patient-controlled delivered oxycodone consumption during the first 6 h was significantly lower in the ISB group (6 mg) than in the SUB group (24.1 mg; P=0.001) or in the PLA group (27 mg; P<0.001). No significant differences were detected between the SUB and PLA groups (P=0.791). The postoperative pain scores during the first 4 h at rest and during the first 6 h on movement were significantly lower in the ISB group than in the SUB and PLA groups. Conclusion: After arthroscopic shoulder surgery SUB has a minor effect only on postoperative analgesia, whereas an ISB with low-dose ropivacaine effectively relieves early postoperative pain and reduces the need for opioids.