Arthroscopic Exploration of the Shoulder Joint through the Posterior Portal
Arthroscopic Exploration of the Shoulder Joint through the Posterior Portal
Order of Scoping
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Insert a 30-degree arthroscope through the posterior incision (see Fig. 1-79).
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Identify the biceps tendon and its origin as it runs from superior to inferior (Fig. 1-83A,B, View 1).
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Next, rotate the arthroscope superiorly to allow visualization of the
supraspinatus (Fig. 1-83A,B, View 2). The supraspinatus lies posterior to the biceps tendon.
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To visualize infraspinatus and teres minor you will need to rotate not only the arthroscope but also the humeral head (Fig. 1-84A,B, View 3).
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Next, note the anterior triangle of the shoulder, formed by the biceps tendon, the superior edge of the subscapularis, and the glenoid (Fig. 1-85A,B, View 4; see Fig. 1-83A,B, View 1). This triangle marks the safe spot for entry through the anterior portal (see Fig. 1-82).
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Pass the arthroscope to the upper anterior margin of the glenoid and rotate the scope inferiorly to allow examination of the anterior glenohumeral complex (Fig. 1-85A,B, View 5). You may need to apply a distraction force to the shoulder at that time, or alternatively use a 70-degree rather than a 30-degree telescope.
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Pass the arthroscope anteriorly into the anterior triangle and rotate the scope so as to allow you to look inferiorly into a space underlying the subscapularis (Fig. 1-85A,B, View 6). This space is a frequent site for loose bodies.
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Next, redirect the arthroscope inferiorly and rotate the telescope posteriorly to allow access to the posterior recess of the shoulder (Fig. 1-86A,B, View 7; see Fig. 1-84). Visualization of the humeral head and glenoid are easily accomplished through the posterior portal. Careful manipulation of the shoulder is required to visualize the whole of the articular surface.
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Figure 1-83 A: Lateral view of the shoulder joint with the scope in place (right), correlated with their respective arthroscopic views (left). View 1: Insert the arthroscope through a posterior approach and identify the biceps tendon. Identify the long head of biceps as it runs superiorly to its origin. Note the position of the arthroscope in the joint and the view obtained. View 2: Rotate the arthroscope superiorly to visualize the rotator cuff. Observe the supraspinatus portion of the rotator cuff. B: Overall views of the shoulder joint seen from the direction of the arthroscope in Views 1 and 2 (left), correlated with their respective arthroscopic views (right).
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Figure 1-84 A: Lateral view of the shoulder joint with the scope in place (right), correlated with its arthroscopic view (left). View 3: Rotate the arthroscope to look inferiorly and identify the inferior portion of the rotator cuff (infraspinatus and teres minor). Rotate the humeral head to visualize the infraspinatus tendon. B: Overall view of the shoulder joint seen from the direction of the arthroscope in View 3 (left), correlated with its arthroscopic view (right).
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Figure 1-85 A: Lateral views of the shoulder joint with the scope in place (right), correlated with their respective arthroscopic views (left). View 4: Advance the arthroscope anteriorly and identify the anterior triangle. Observe the anterior triangle formed by the biceps tendon, the superior edge of subscapularis, and the glenoid labrum. View 5: Pass the arthroscope to the upper margin of the glenoid and rotate the arthroscope inferiorly. Observe the anterior glenohumeral complex. View 6: Pass the arthroscope anteriorly and then rotate it to allow you to look
inferiorly. Observe the space underlying the subscapularis. Direct the arthroscope inferiorly and then rotate it to look posteriorly. B: Overall views of the shoulder joint seen from the direction of the scope in Views 4, 5, and 6 (left), correlated with their respective arthroscopic views (right).
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Figure 1-86 A: Lateral view of the shoulder joint with the scope in place (right), correlated with its arthroscopic view (left). View 7: Direct the arthroscope inferiorly and then rotate it to look posteriorly. Observe the posterior recess of the shoulder. B: Overall view of the shoulder joint seen from the direction of the arthroscope in View 7 (left), correlated with its arthroscopic view (right).
Dang
Nerves
Posterior. The axillary nerve leaves the posterior wall of the axilla by penetrating the quadrangular space. It winds around the humerus running on the deep surface of the deltoid muscle, about 7 cm below the tip of the acromion (see Figs. 1-26, 1-36, 1-52, and 1-71). If the posterior portal is correctly located with regard to the posterolateral tip of the acromion, this portal should lie about 3 cm superior to the nerve. Only a very inferiorly placed incision will endanger the nerve.
The suprascapular nerve, the nerve supplied to both the supraspinatus and infraspinatus, runs around the base of the spine of the scapula as it runs from the supraspinatus fossa to the infraspinatus fossa (see Figs. 1-58 and 1-72). This nerve is at risk if the posterior portal is made too medially. The correctly positioned portal is approximately 2 cm lateral to the nerve.
Anterior. The axillary nerve may be in danger as it traverses along the deep surface of the deltoid from inferiorly placed incisions.
The musculocutaneous nerve, the nerve supply of the flexor muscles of the upper arm, enters those muscles some 2 to 8 cm distal to the tip of the coracoid process. The nerve, therefore, is unlikely to be damaged by a portal made superior and lateral to the level of the coracoid process (see Figs. 1-13, 1-21, and 1-25).
Vessels
The cephalic vein runs superficially between the deltoid and pectoralis major muscle. It can only be damaged from incisions made too laterally.
The acromial branches of the thoracoacromial artery lie along the medial side of the coracoacromial ligament and will not be endangered through the classic anterior portal. Branches of the artery will, however, be damaged by more superior approaches used to enter the subacromial space.
How to Enlarge the Approach
To use the posterior portal to access the subacromial space, withdraw the arthroscope from the shoulder; using the same skin incision, redirect the scope more superiorly to run on the underside of the acromion. To do this you will need to create a separate arthroscopic penetration of the deltoid
muscle. Access to the subacromial space is often difficult due to disease processes, especially of the subacromial bursa. Continuous traction is indicated. Bleeding is frequently encountered.
The anterior portal cannot be extended.