The 7-o'clock posteroinferior portal for shoulder arthroscopy.

Abstract

Access to the inferior glenohumeral joint of the shoulder is very limited through the traditional 2- or 3-o'clock anterior portals. The 7-o'clock posteroinferior portal offers an excellent alternative approach. Descriptive anatomic study. 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. 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 degrees and to the suprascapular nerve was 33 degrees. The 7-o'clock portal affords safe, direct working access to the inferior capsular recess of the glenohumeral joint. The 7-o'clock portal is a safe and effective technique for use by shoulder surgeons.