The 7-o'clock Posteroinferior Portal for Shoulder Arthroscopy

Abstract

Background: Access to the inferior glenohumeral joint of the shoulder is very limited through the traditional 2- or 3-o'clock anterior portals. Hypothesis: The 7-o'clock posteroinferior portal offers an excellent alternative approach. Study Design: Descriptive anatomic study. Methods: Six paired cadaveric shoulders were used to arthroscopically develop and test a 7-o'clock posteroinferior portal. The distances between the portal and the subscapular and axillary nerves were measured with the arm in six different positions, combining flexion, extension, abduction, and adduction. Results: The distance from the 7-o'clock posteroinferior portal to the axillary nerve was 39 ± 4 mm and to the suprascapular nerve was 28 ± 2 mm. There was no statistically significant nerve-to-portal differential distance when the arm was placed in flexion, extension, abduction, or adduction. The inside-to-outside technique produced a 7-o'clock posteroinferior portal approximately 5 mm further from both the axillary and suprascapular nerves than did the outside-to-inside method. The angle of divergence from the 7-o'clock posterior portal skin incision to the axillary nerve was 47° and to the suprascapular nerve was 33°. Conclusions: The 7-o'clock portal affords safe, direct working access to the inferior capsular recess of the glenohumeral joint. Clinical Relevance: The 7-o'clock portal is a safe and effective technique for use by shoulder surgeons.