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

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).

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.

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.

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.