Accuracy of subacromial injection: anterolateral versus posterior approach

Subacromial bursa injection is commonly performed via an anterolateral or posterior approach. No study has compared the accuracy rates of these approaches. Twenty cadaveric shoulders were injected with radiocontrast in the subacromial bursa via an anterolateral approach and twenty via a posterior approach. Ten shoulders were injected with methylene blue via each technique for dissection. The anterolateral approach was accurate by fluoroscopy in 18 shoulders (90%), but dissection of 10 shoulders revealed successful injection in only 6 (60%). The posterior approach was judged to be successful in 16 shoulders (80%), and dissection of 10 shoulders confirmed 8 injections (80%) were accurate. There was no significant difference in the accuracy by fluoroscopy (P=.38) or dissection (P=.33). The accuracy rates of the anterolateral and posterior approaches to subacromial bursa injections are not significantly different. The anterolateral approach may place injected material medial to the medial bursal boundary, and fluoroscopy may not accurately assess this placement.