Review Question - QID 214083

This patient has medial biceps subluxation and a subscapularis tear. The band of tissue is the comma sign, which is composed of the coracohumeral ligament (CHL) and superior glenohumeral ligament (SGHL).

Recognizing and differentiating anatomic variants of the rotator interval from true pathologic findings is essential for successful shoulder arthroscopy. The comma sign was recognized to be indicative of subscapularis tendon tears, which can be difficult to visualize during routine arthroscopy. It is composed of the CHL and SGHL which consistently insert on the superolateral subscapularis and humerus. The SGHL and CHL also form and maintain the medial biceps sling, which explains why these structures are disrupted as a unit. Identifying the comma sign tissue and following it inferiorly will locate the subscapularis tendon, which can be significantly retracted and scarred medially to the glenoid.

Lenart and Ticker discussed subscapularis tear management. They described the utility of the comma sign in identifying subscapularis tears and serving as a reduction aid when a traction stitch is placed. When the subscapularis is properly repaired to the lesser tuberosity, the comma tissue will rest in its native location as well. They also recommend addressing the biceps tendon pathology.

Frank et al. discussed the anatomy of the rotator interval. They detail that the rotator interval contains the CHL, SGHL, long head of biceps tendon, and capsular tissue, and functions to restrict inferior translation of the adducted humeral head. They showed that by side to side closure of the interval, external rotation of the humeral can be significantly limited, which may play a role in instability.

Paxton et al. reviewed the basic principles of shoulder arthroscopy. They point out that both beach chair position and lateral decubitus positions have different advantages and disadvantages, most notably the beach chair allows easy conversion to open procedures while lateral decubitus positing avoids cerebral hypoperfusion. They also emphasized that proper positioning and padding of bony prominences is critical to prevent completely avoidable pressure ulcers or compression neurapraxias.

Figure A is a left shoulder in the beach chair position viewed from the posterior portal, demonstrating the comma sign, which retracted medially with the edge of the subscapularis tendon. There is a traction stitch placed in this. Illustrations A and B are an arthroscopic view of a right shoulder undergoing subscapularis repair. Following repair completion, the comma sign tissue is restored to its native position. Illustration C shows the relationship of the glenohumeral ligaments with the tendinous structures of the shoulder.

Incorrect Answers:
Answers 1 and 2: The MGHL is deep to the subscapularis tendon and can be mistaken for it. It functions to restrain the humerus from anterior translation when in 45 degrees of abductions.
Answer 4: The rotator cable is the termination of the CHL, which spans the supraspinatus tendon from anterior to posterior.
Answer 5: The coracoacromial ligament (CA) is extra-articular and is helps contain the humeral head in instances of rotator cuff arthropathy.