Patient positioning for shoulder arthroscopy based on variability in lateral acromion morphology.

The purpose of this article is to highlight the variability among shoulders in the relationship between the lateral acromion and the humeral head and to describe how this variability may influence a surgeon's choice of patient positioning for shoulder arthroscopy. In cases of increased lateral coverage of the humeral head by the acromion, arthroscopic access to the superior aspect of the glenoid through lateral portals becomes increasingly difficult because of a narrowed corridor of approach. Placing the ipsilateral arm in traction will lower the station of the humeral head and widen the arthroscopic corridor of approach to the superior labrum. Based on preoperative assessment of lateral acromion morphology, if the surgeon determines that inferior displacement of the humeral head of 25% or more of the humeral head diameter will be necessary to achieve adequate arthroscopic accessibility of the superior glenoid through lateral portals, we recommend the lateral decubitus position with continuous traction on the ipsilateral arm over the beach-chair position.