Arthroscopic capsular release for the stiff shoulder. Description of technique and anatomic considerations.

The anatomic proximity of several neurovascular structures remains a major concern to the surgeon interested in performing arthroscopic capsular release. We evaluated the anatomic relationships between the released capsule and the axillary nerve, posterior circumflex humeral artery, and brachial artery in a frozen cadaveric model. With the aid of electrocautery, seven cadaveric shoulders underwent complete arthroscopic capsular release. The release was performed circumferentially, approximately 1 cm lateral to the glenoid rim. All shoulders were subsequently frozen and sectioned through the plane of the capsular release while the shoulder was maintained in the lateral arthroscopic position (45 degrees of abduction and 20 degrees of flexion). Anatomic dissection revealed an average distance from the capsular release to the axillary nerve of 7.04 mm (95% confidence interval, 5.62, 8.47), to the posterior circumflex humeral artery of 8.2 mm (95% confidence interval, 6.41, 9.99), and to the brachial artery of 15.97 mm (95% confidence interval, 9.85, 22.09). As the axillary nerve was followed medially from the released capsule, the inferior border of the subscapularis muscle became interposed between the capsule and the axillary nerve. This limited anatomic study shows that a relatively safe margin between the capsule and the neighboring neurovascular structures can be obtained by releasing the capsule within 1 cm of the glenoid rim.