Regional Anesthesia Procedures for Outpatient Shoulder Surgery Reginald E. Julien, MD Brian A. Williams, MD, MBA Of all the joints in the human body, the shoulder is unique. The shoul- der (glenohumeral) joint is a multiaxial spheroidal joint that possesses 3 degrees of freedom. 1 This tremendous mobility is a great asset, but it is also a great weakness. The shoulder possesses the greatest range of motion of any joint in the human body, but at the same time it is inherently the least stable. 2 As a result, the shoulder joint is very vulnerable to injury. Anatomically, the joint is surrounded by a fibrous capsule and held in place by 3 ligaments: the glenohumeral, coracohumeral, and the transverse humeral ligaments. Additional support is given to the joint in the form of several muscles that surround it. There are a total of 6 intrinsic muscles to the shoulder: the deltoid, teres major, and the 4 muscles of the rota- tor cuff. The deltoid is the largest of the 6 muscles. The tendons of the supraspinatus, infraspinatus, subscapularis, and teres minor muscles make up the rotator cuff. 3 Each year, thousands of Americans sustain injuries to the glenohum- eral joint or its surrounding muscles. Most shoulder injuries are managed conservatively with rest and physical therapy; however, chronic shoulder pain and/or decreased functionality of the affected limb lead many to seek orthopedic surgical correction. 2 In fact, shoulder pain is a common reason people seek out medical care. Epidemiologic studies suggest that shoulder pain ranks third among complaints patients give as a reason for a doctor visit, second only to headache and back pain. 4 For every 1000 people, 17 have impairment of the shoulder or upper extremity. 5 For some, these impairments are chronically debilitating, and cumulatively they result in 58 million person-days per year lost or 13 days per impairment. 5 These impairments require 11 million days of bedrest per year, or approximately 2 bedrest days per impairment. 5 Some two and one half million patients present annually to their physicians for shoulder-related pain or symptoms; of that number, approximately 300,000 go on to have surgical correction 167