Introduction Overview provides access to the lateral proximal humerus, rotator cuff, and acromion it is not traditionally extensile -- to extend the approach distally, a second separate incision must be made or one long incision can be made, with identification of the axillary nerve being paramount Indications reduction and fixation of proximal humerus fractures rotator cuff repair debridement of the subacromial space Anesthesia General Regional Internervous plane Internervous plane no true internervous plane (deltoid is split in line with its fibers) Positioning & Preparation Position approach is done in a supine position, with a bump or roll placed under the spine or ipsilateral scapula elevation of the head of the table reduces venous pressure in the operative field alternatively, a 'beach chair' positioning adaptor may be used depending on surgeon preference the operative arm should be at the edge of the table to allow greatest manipulation of the extremity Intraoperative imaging C-arm can either come from above the head or across the bed from the opposite side of the table ensure adequate fluoroscopic views can be obtained prior to preparation and draping Approach Incision 5 cm incision is made from the tip of the acromion distally in line with the arm this is generally made at the posterior edge of the clavicle, but can be adjusted according to pathology Superficial dissection deltoid is split in line with its fibers no more than 5 cm distal to the lateral edge of acromion (to protect the axillary nerve) a stay suture is placed at the inferior apex of the split to prevent propogation of the split Deep dissection subacromial bursa lies directly deep to the deltoid muscle and can be excised to reveal the underlying rotator cuff insertion and proximal humerus Extension distal extension is only possible by performing a second, separate deltoid split distal to the axillary nerve the approach can be extended proximally parallel to the spine of the scapula to expose the entire supraspinatus this requires division of the overlying trapezius muscle parallel to the spine of the scapula and division of the acromion in line with the incision, both of which require repair Dangers Axillary nerve leaves posterior aspect of axilla by traversing quadrilateral space (teres minor, teres major, long head of triceps, medial border of humerus) it travels around the humerus coursing anteriorly and laterally to enter and innervate the deltoid via its deep surface at this point, it runs transversely 5-7 cm distal to the edge of the acromion from posterior to anterior cannot extend split further due to risk to denervation of anterior deltoid need to make a second incision distally in order to provide a safe "second window" if distal extension is needed (generally for fractures)