Comparative survey of pain-alleviating effects between ultrasound-guided injection and blind injection of lidocaine alone in patients with painful shoulder

Complaints of shoulder pain are very frequent in clinical practice. To relieve this type of pain, intra-subacromial bursa (SAB) injection therapy is commonly employed. Injection procedures include blind and ultrasound-guided injection. In clinical practice, blind injection is routinely performed. However, the SAB is a very thin tissue. Poor response to blind injection may be due to a misplaced injection. It is assumed that ultrasound-guided injections are more effective than blind injections. The purpose of this study was to compare pain-alleviating effects between ultrasound-guided injection and blind injection with lidocaine alone. The subjects were 16 patients (20 shoulders) in whom pain was possibly derived from inflammation of the SAB. Initially, ultrasound-guided injection was performed with 2 ml of 1% lidocaine. After 1 week, blind injection was conducted in the same patient. They subjectively expressed the grade of pain at each time point (before and 1, 5, 10, 15, 20, 25, and 30 min after injection) as pain scores. We calculated the amelioration rate by dividing differences between the scores at each time point and before injection by the pre-injection score. Pain scores of ultrasound-guided injection were lower than blind injection. Ultrasound-guided injection achieved higher mean amelioration rates compared to blind injection, showing significant differences at all time points (P < 0.01). Ultrasound-guided technique achieved higher effectiveness compared to blind technique.