The anatomic relationship of the brachial plexus and axillary artery to the glenoid. Implications for anterior shoulder surgery.

Iatrogenic brachial plexus injury is an uncommon but potentially severe complication of shoulder reconstruction for instability that involves dissection near the subscapularis muscle and potentially near the brachial plexus. We examined the relationship of the brachial plexus to the glenoid and the subscapularis muscle and evaluated the proximity of retractors used in anterior shoulder surgical procedures to the brachial plexus. Eight fresh-frozen cadaveric shoulders were exposed by a deltopectoral approach. The subscapularis muscle was split in the middle and dissected to reveal the capsule beneath it. The capsule was split at midline, and a Steinmann pin was placed in the equator of the glenoid rim under direct visualization. The distance from the glenoid rim to the brachial plexus was measured with calipers with the arm in 0 degrees, 60 degrees, and 90 degrees of abduction. The brachial plexus and axillary artery were within 2 cm of the glenoid rim, with the brachial plexus as close as 5 mm in some cases. There was no statistically significant change in the distance from the glenoid rim to the musculocutaneous nerve, axillary artery, medial cord, or posterior cord with the arm in various degrees of abduction. Retractors placed superficial to the subscapularis muscle or used along the scapular neck make contact with the brachial plexus in all positions tested.