Arthroscopic Anatomy of the Shoulder and Cuff


Chapter 2

Arthroscopic Anatomy of the Shoulder and Cuff



George Sanchez, Marcio B. Ferrari, Jason T. Hamamoto, John Daley Higgins, and Rachel M. Frank

Introduction



Surgical Anatomy





  1. • Long head of the biceps tendon (LHBT) (Fig. 2.2): the LHBT originates from the supraglenoid tubercle of the glenoid and superior labrum, and extends distally into the bicipital groove along the proximal humerus. The tendon is stabilized within the groove by the overlying transverse humeral ligament. A normal and healthy LHBT typically has a smooth appearance and is white in color. During arthroscopic evaluation, the portion of the tendon within the bicipital groove should be pulled into the joint space using a probe to inspect for signs of inflammation, fraying, or tearing. The “lipstick sign,” an increased erythema visualized in the intertubercular part of the tendon when retracted to the intraarticular cavity, indicates bicipital tendonitis. The proximal 4 cm of the LHBT is intraarticular and easily evaluated. However, the degenerative portion of the tendon may be situated extraarticularly. Therefore, using a nerve hook or probe through the anterior portal, the tendon can be displaced inferiorly, thereby exposing an additional 3 to 5 cm of the tendon for arthroscopic visualization. The proximal attachment site of the tendon at the level of the superior labrum should also be inspected for presence of superior labrum pathology, including a possible superior labrum anterior to posterior (SLAP) lesion. The surgeon must be aware of SLAP variants, including sublabral recess (sulcus), sublabral hole, and Buford complex. This can be accomplished by moving the arm from an adducted position in neutral rotation to 90 degrees of abduction and fully externally rotated to 90 degrees. The LHBT and superior labral complex should be inspected through the anterior portal for presence of a SLAP lesion. Abduction and external rotation of the arm helps evaluate if the superior labrum is elevated from its glenoid attachment. Arthroscopic pathology should always be evaluated in conjunction with clinical findings, as often, abnormal tissue, even if present, is not pathologic but simply incidental in nature.
  2. • Superior glenohumeral ligament (SGHL) (Figs. 2.3, 2.4): the SGHL is contained within the triangular space known as the rotator interval. The superior aspect of the SGHL originates from the supraglenoid tubercle near the anterior portion of the LHBT and inserts into the fovea capitis humeri and on the anterior margin of the bicipital groove. The SGHL serves as a check-rein to inferior humeral head translation over the glenoid fossa at 0 degrees of abduction. In patients with anterior and/or inferior instability, the SGHL and middle glenohumeral ligament (MGHL) may be torn or attenuated.

  3. image
    FIG. 2.1 Soft tissue stabilizers including the glenoid labrum, glenohumeral ligaments, and the glenohumeral joint capsule. 
    From Provencher MT, Romeo AA. Shoulder Instability: A Comprehensive Approach. Philadelphia: Saunders; 2012.


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    FIG. 2.2 (A) The right glenohumeral joint viewed from the posterior portal. The glenoid (G) is on the left and the humeral head (H) is on the right. (B) Looking just superior to A, the insertion of the long head of the biceps tendon (LHBT ) into the superior labrum is seen. (C) The biceps is followed from the mid left portion of the picture as it exits the glenohumeral joint. An intact supraspinatus (SS) is seen as it inserts at the articular margin of the humeral head (H). (D) An intact inferior labrum and glenohumeral ligament are visualized at the inferior aspect of the figure. 
    From Miller MD, Thompson SR. DeLee & Drez’s Orthopaedic Sports Medicine. Philadelphia: Saunders; 2012.

  5. • Middle glenohumeral ligament (MGHL) (Fig. 2.5): the MGHL originates from the supraglenoid tubercle and superior labrum and continues over the subscapularis tendon. This ligament resists anterior and posterior translation of the humeral head between 0 and 45 degrees of abduction in external rotation (ABER position). The surgeon must be aware of an important anatomic variation that may exist regarding the MGHL: the Buford complex (Fig. 2.6). A Buford complex is a congenital glenoid labrum anatomic variant in which the anterosuperior labrum is not present and the MGHL inserts directly into the LHBT. This should not be confused with a labral tear, and arthroscopic findings must be correlated with clinical and imaging findings to determine which arthroscopic findings are truly clinically relevant and which are simply incidental in nature. In patients with adhesive capsulitis, the SGHL and MGHL may be significantly scarred or diffusely inflamed.


  7. image
    FIG. 2.3 Drawing of the rotator interval in a right shoulder. A, Coracohumeral ligament; B, long head of biceps tendon (red); C, superior glenohumeral ligament (green); D, tendinous slip (yellow); E, transverse humeral ligament (beige); F, subscapularis muscle. 
    From Toussaint B, Barth J, Charousset C, et al. New endoscopic classification for subscapularis lesions. Orthop Traumatol Surg Res. 2012;98(8):S186–S192.


  8. image
    FIG. 2.4 Arthroscopic view of the rotator interval. SGHL, Superior glenohumeral ligament; Lgt Hum Trans, transverse humeral ligament; SSC, subscapularis tendon. 
    From Toussaint B, Barth J, Charousset C, et al. New endoscopic classification for subscapularis lesions. Orthop Traumatol Surg Res. 2012;98(8):S186–S192.

  9. • Subscapularis tendon: the subscapularis tendon (Fig. 2.4) serves as an anatomic landmark during arthroscopic evaluation and defines the inferior border of the rotator interval. The subscapularis originates from the subscapular fossa of the scapula and inserts into the lesser tuberosity of the humerus, which can be visualized intraoperatively. To improve visualization of the humeral insertion, the arm should be moved into forward flexion and internal rotation. The LHBT may subluxate out of the bicipital groove and continue inferiorly in the presence of a subscapularis tear. A tear in the subscapularis is best seen with internal and external rotation of the arm. In the setting of a chronic, retracted subscapularis tear, an arc may be formed by the SGHL and coracohumeral ligament complex, which serves as a marker of the superolateral corner of the chronic subscapularis tear (Fig. 2.7). The MGHL and the subscapularis are in close contact, with the MGHL situated posterior to the superior margin of the subscapularis muscle. The mean subscapularis insertion area on the lesser tuberosity is 2.41 cm2 while the mean medial-to-lateral insertion length is 1.79 cm and the mean anterior-to-inferior length is 2.43 cm.

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    FIG. 2.5 Arthroscopic view of left shoulder from the posterior portal showing the middle glenohumeral ligament (MGHL) draping over the subscapularis tendon. 
    From Nguyen D. Anatomy, examination, and imaging of the shoulder. Oper Tech Orthop. 2008;18(1):2–8.


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    FIG. 2.6 Example of a Buford complex with a cord-like middle glenohumeral ligament (double dots) underneath the probe attaching to the anterior biceps (single dot) and a sublabral foramen inferior to the middle glenohumeral ligament. 
    From Rockwood CA, Matsen FA, Wirth MA, Lippitt SB, Fehringer EV, Sperling JW. Rockwood and Matsen’s The Shoulder. 5th ed. Philadelphia: Elsevier; 2017.



  13. image
    FIG. 2.7 Arthroscopic view of the comma sign. SSP, supraspinatus tendon; SSC, subscapularis tendon. 
    From Toussaint B, Barth J, Charousset C, et al. New endoscopic classification for subscapularis lesions. Orthop Traumatol Surg Res. 2012;98(8):S186–S192.

  14. • Glenoid labrum: the labrum is a fibrocartilaginous structure that surrounds the glenoid rim to deepen the glenoid fossa for enhanced glenohumeral stability (Fig. 2.8). The labrum is circumferentially divided into six “sectors.” The labrum serves as an attachment site for the glenohumeral ligaments, long head of the biceps brachii muscle, and surrounding capsule. The standard posterior portal and posterolateral accessory portal (7 o’clock portal) and multiple anterior portals (standard midglenoid portal, trans-subscapularis portal, etc.) can be used to conduct a 360-degree assessment of the labrum. The anterior portals are especially helpful as viewing portals when evaluating suspected posterior labral pathology (Fig. 2.9). The anteroinferior labrum must be meticulously inspected for the presence of avulsion injury of the glenoid rim, known as a Bankart lesion (Fig. 2.10), which is the critical lesion in patients with anterior shoulder instability. The anterior glenoid rim can also be evaluated, which may reveal evidence of attritional bone loss in the setting of chronic and/or recurrent instability. When the surrounding periosteum peels off from the glenoid, an anterior labral periosteal sleeve avulsion (ALPSA) injury is then present (Fig. 2.11).
  15. • Inferior glenohumeral ligament (IGHL): the IGHL is divided into anterior, posterior, and superior segments. The anterior IGHL (AIGHL) originates from the 2 and 4 o’clock position (based on a right shoulder) on the glenoid and functions as the most important restraint to anterior and inferior translation of the humeral head on the glenoid when the shoulder is in 90 degrees abduction and full external rotation. The AIGHL anchors into the anterior labrum and forms a connection susceptible to attenuation with potential tearing in the event of an anterior shoulder subluxation or dislocation. The posterior IGHL originates from the 7 to 9 o’clock position (based on a right shoulder), and is the most important check-rein to posterior subluxation at 90 degrees of flexion and internal rotation. The superior IGHL is particularly essential for static stabilization of the shoulder joint and usually injured at its proximal attachment following dislocation. Injury to the inferior capsular structures can occur in isolation or in combination with labral tears leading to instability of the shoulder joint. As a result, the surgeon may appreciate decreased soft tissue constraint and a positive “drive through” sign intraoperatively (Fig. 2.12). The glenohumeral ligament site of origin on the labrum and site of insertion in the humerus should be thoroughly inspected during the arthroscopic examination. Avulsion injuries can occur at the humeral head. These are referred to as humeral avulsion of the glenohumeral ligament (HAGL) (Fig. 2.13) and reverse humeral avulsion of the glenohumeral ligament (RHAGL), and may be subtle.

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    FIG. 2.8 Labral “sectors”: I, superior; II, anterior superior; III, anterior inferior; IV, inferior; V, posterior inferior; and VI, posterior superior. BA, biceps anchor; SGL, superior glenohumeral ligament; MGHL, middle glenohumeral ligament; IGHL, inferior glenohumeral ligament. 
    From Zlatkin MB, Sanders TG. Magnetic resonance imaging of the glenoid labrum. Radiol Clin North Am. 2013;51(2):279–297.

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    Patient Positioning and Anesthesia for Rotator Cuff Surgery Arthroscopic Trillat Procedure for Recurrent Anterior Shoulder Instability With Associated Irreparable Rotator Cuff Tear Nonoperative Care of Rotator Cuff Disorders: Physical Therapy, Modalities, and Injectables What Type of Rotator Cuff Tear Is This? Tear Pattern Recognition and Soft-Tissue Releases Subscapularis Tendon Tears: Arthroscopic Management Shoulder Stiffness (Adhesive Capsulitis) With A Rotator Cuff Tear: How to Manage

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Mar 28, 2020 | Posted by in ORTHOPEDIC | Comments Off on Arthroscopic Anatomy of the Shoulder and Cuff

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