Arthroscopic anatomy of the subdeltoid space

Abstract

From the first shoulder arthroscopy performed on a cadaver in 1931, shoulder arthroscopy has grown tremendously in its ability to diagnose and treat pathologic conditions about the shoulder. Despite improvements in arthroscopic techniques and instrumentation, it is only recently that arthroscopists have begun to explore precise anatomical structures within the subdeltoid space. By way of a thorough bursectomy of the subdeltoid region, meticulous hemostasis, and the reciprocal use of posterior and lateral viewing portals, one can identify a myriad of pertinent ligamentous, musculotendinous, osseous, and neurovascular structures. For the purposes of this review, the subdeltoid space has been compartmentalized into lateral, medial, anterior, and posterior regions. Being able to identify pertinent structures in the subdeltoid space will provide shoulder arthroscopists with the requisite foundation in core anatomy that will be required for challenging procedures such as arthroscopic subscapularis mobilization and repair, biceps tenodesis, subcoracoid decompression, suprascapular nerve decompression, quadrangular space decompression and repair of massive rotator cuff tears.

Keywords: anatomy; arthroscopy; subdeltoid space.

Figure 1.

A) Insertion of the supraspinatus and Infraspinatus tendons is visualized on the rotator cuff fooprint on the greater tuberosity (lateral viewing portal). B) Insertion of the Infraspinatus and teres minor is visualized (lateral viewing portal). C) Visualization of the coracoacromial ligament from posterolateral viewing portal.

Figure 2.

A) Undersurface of the acromion and resected distal clavicle as viewed from a lateral portal. B) The coracohumeral ligament is identified in an anterosuperior rotator cuff tear (lateral viewing portal). Notice how it attaches to both the leading rolled border of the subscapularis and the leading edge of the supraspinatus. C) The triangular interval formed by the anterior border of the supraspinatus, the medial border of the coracoacromial (CA) ligament, and the undersurface of the acromioclavicular (AC) joint is entered (from lateral viewing portal) to gain access to the coracoclavicular ligaments. D) The posterior aspect of the coracoclavicular ligaments is identified from a posterior viewing portal anterior to the supraspinatus plane. E) With the arthroscope advanced more medial compared with figure 2d, the posterior aspect of the coracoacromial ligaments is identified from a lateral viewing portal anterior to the supraspinatus plane. The schematic on the right demonstrates the conoid ligament, the transverse scapular ligament (TSL) and the base of the coracoid. F) The resected transverse scapular ligament (TSL) along with the decompressed suprascapular nerves are identified from a lateral viewing portal.

Figure 3.

A) The conjoint tendon and the subscapularis muscle tendon units define the anterior and posterior boundaries of the subcoracoid space, respectively, and can be visualized from a lateral viewing portal. B) With the arthroscope advanced more medially compared with Figure 3a, the deep aspect of the conjoint tendon and medial subscapularis muscle tendon unit can be seen. After a careful bursectomy in this area, the axillary nerve can also been seen along the lower border of the subscapularis. C) The axillary nerve visualized in the subcoracoid space from a lateral viewing portal. D) The conjoint tendon and the deep portion of the pectoralis major tendon can be visualized during the dissection required for an arthroscopic biceps tenodesis. This view is appreciated from a lateral viewing portal at the junction of the anterior and middle thirds of the acromion with the arm in a forward flexed and slightly abducted position.

Figure 4.

A) The scapular spine (as viewed from a lateral portal) can be used to delineate the border between the supraspinatus and Infraspinatus. By following the scapular spine medially, dissection to the spinoglenoid notch can also be performed. B) Identification of the axillary nerve and posterior humeral circumflex artery (PHCA) in the quadrangular space from a posterior viewing portal.