For the beach chair position, the patient is positioned supine and the back of the bed is elevated to 60 degrees (Fig. 1-1). The patient is positioned such that the medial border of the scapula is just lateral to the lateral aspect of the bed. A rolled towel placed just medial to the scapula may improve operative positioning. For the lateral decubitus position, the patient is supported with either a vacuum beanbag or a combination of bolsters, kidney rests, chest strap, foam headrest, and axillary roll (Fig. 1-2). Visualization may be more anatomic if the patient is tilted 20 to 30 degrees posteriorly to bring the face of the glenoid parallel to the floor. Care should be taken to protect and pad superficial bony landmarks of the lower extremities. Ten pounds of traction is typically adequate. The lowest amount of weight (maximum 15 pounds) and shortest time of traction (maximum 2 hours) necessary to perform the procedure are recommended. In addition to axial traction, joint distention may be augmented by the addition of secondary traction close to the axilla and perpendicular to the joint. Caution should be exercised with dual traction setups to avoid distal hypoxemia. Alternatively, a sterile rolled towel placed deep into the axilla may provide improved joint distention without the need for a dual traction setup. For access to the subacromial space, smaller degrees of flexion and abduction can provide inferior distraction of the humeral head and an improved subacromial view.

Figure 1-1 Patient in beach chair position with an articulated arm holder in place with landmarks and portals identified.

Figure 1-2 Patient in lateral decubitus position with traction in place with landmarks and portals identified. AC, Acromioclavicular.

After induction of anesthesia but before sterile preparation and draping, an examination with the patient under anesthesia (EUA) should be performed. Both the operative and nonoperative limb should be examined, if possible. Degrees of abduction, forward elevation, and internal and external rotation in adduction and abduction, respectively, should be documented. Restrictions in motion may be observed in patients with adhesive capsulitis, glenohumeral arthritis, or frank shoulder dislocation. In patients with a history of instability, an examination for shoulder laxity should be performed via load and shift testing. After application of a force to center the humerus on the glenoid, the humerus is translated in both an anterior and a posterior direction while 90 degrees of abduction are maintained. Translation is graded as 0 for no translation, 1+ for trace translation, 2+ for translation to the edge of the glenoid, and 3+ for translation over the edge of the glenoid. Laxity to an inferiorly directed humeral force in adduction is documented as 0 for no humeral movement, 1+ for 1 cm of inferior humeral movement, 2+ for 2 cm of humeral movement, and so on.² If external humeral rotation dampens the inferior translation, the rotator interval may need to be addressed in addition to other sources of pathologic shoulder laxity.

After EUA the shoulder is prepared and draped in a sterile fashion. For the beach chair position, a sterile drape is placed over the arm holder for sterile intraoperative readjustment. For the lateral decubitus position, the arm is wrapped with Coban (3M, St Paul, Minnesota) for sterile arm traction up to but not including the wrist to avoid superficial radial nerve compression. Indelible ink is used to mark the anterior and posterior borders of the clavicle, borders of the acromion, and scapular spine. The AC joint and the coracoid process are identified and marked (see Figs. 1-1 and 1-2).

Portal Placement

Proper portal placement is essential for both surgical visualization during diagnostic arthroscopy and access of instruments used for the treatment of shoulder pathology. Improper portal placement can make even the simplest arthroscopic task seem near impossible. Planned portal sites should be marked before insufflation of the joint, to avoid obscuring palpable landmarks. The skin and subcutaneous tissue of portal sites should be infiltrated with 0.25% bupivacaine with epinephrine before incision.

Posterior Portal

In either the beach chair or lateral decubitus position, shoulder arthroscopy begins with the establishment of a posterior viewing portal. In the beach chair position this portal is classically located in the “soft spot” 2 cm medial and 2 cm inferior to the posterolateral corner of the acromion. In the lateral decubitus position the posterior portal may be positioned further laterally, just off the posterolateral corner of the acromion. An easy way to identify the posterior portal in the lateral decubitus position is to place the tip of the second finger on the coracoid process, the tip of the index finger in the soft space just posterior to the AC joint, and the tip of the thumb posteriorly over the presumed portal location. The portal lies in the sulcus between the humeral head and the glenoid. Regardless of shoulder position, an 18-gauge spinal needle is placed through the skin and into the glenohumeral joint, aiming toward the coracoid process. The joint is then insufflated with 30 to 50 mL of saline, with attention paid to ease of injection. The syringe is then briefly removed to visualize fluid egress, also confirming an intraarticular position. The spinal needle is then briskly removed and an 8-mm skin incision is made in its place through the skin and subcutaneous tissue with an 11 blade scalpel. A blunt obturator is then placed through the incision, aiming toward the coracoid process in the same trajectory as the spinal needle. Prior joint insufflation assists with shoulder distention, decreasing the risk of iatrogenic damage to the articular surface during portal placement. With the beach chair position, an assistant may provide gentle glenohumeral distraction by abducting the shoulder under the axilla while maintaining the elbow in an adducted position. Although the posterior portal theoretically takes advantage of the neurovascular plane between the teres minor muscle (axillary nerve) and the infraspinatus muscle (suprascapular nerve), it commonly pierces the belly of the infraspinatus muscle. Dangers to posterior portal placement include the axillary nerve, which lies 3 cm inferior to the placement site, and the suprascapular nerve, which lies 2 cm medial to the placement site.

Anterior Portals

The anterior portal is best placed with an “outside-in” technique, through use of a spinal needle placed under direct arthroscopic visualization (Fig. 1-3). The position of the anterior portal may vary based on the goals of the procedure. For anterior instability, placement of the portal just above the subscapularis is desirable. The portal may be placed more centrally within the rotator interval for routine diagnostic arthroscopy (Fig. 1-4). Superficially, this portal is located just lateral to the coracoid process. It travels between the deltoid muscle (axillary nerve) and the pectoralis major (lateral and medial pectoral nerves). In the deeper layer the anterior portal travels in the interval between the supraspinatus (suprascapular nerve) and the subscapularis (upper and lower subscapular nerves). The portal is also inferior to the long head of the biceps tendon (LHBT) and just lateral to the middle glenohumeral ligament (MGHL). Safety of the anterior portal is ensured by making the portal under direct visualization, incising only the skin and subcutaneous tissue with the scalpel, and remaining lateral to the coracoid process, protected from critical neurovascular structures.