Which joint position puts the axillary nerve at lowest risk when performing arthroscopic capsular release in patients with adhesive capsulitis of the shoulder?

The success of arthroscopic capsular release of the glenohumeral joint depends on complete incision of the inferior capsule. This study determined the distance between capsule and the axillary nerve in different joint positions. In 14 human shoulder specimens the anterior joint capsule and axillary nerve were dissected, and the anterior joint capsule was incised between the 1 and 5 o'clock positions. The shortest distance between the insertion of the inferior capsule and the axillary nerve was measured at the glenoid and humeral insertions in abduction, adduction, internal, and external rotation. The axillary nerve is surrounded from soft connective tissue and is closer to the humeral than to the glenoidal attachment of the joint capsule. During abduction and external rotation the nerve stays in its position while the glenohumeral capsule tightens, which increases the distance between the two structures. This results in the following distances: to the glenoidal/humeral capsule insertion: in adduction and neutral rotation, 21.2+/-4.2/14.2+/-2.6 mm; in abduction and neutral rotation, 24.0+/-4.9/15.0+/-5.0 mm; in abduction and internal rotation, 21.1+/-6.6/14.6+/-3.7 mm; and in abduction and external rotation, 24.9+/-3.8/16.4+/-4.4 mm. Thus, when performing arthroscopic capsular release the incision of the glenohumeral joint capsule should be undertaken at the glenoidal insertion in the abducted and externally rotated shoulder.