The Role of the Subscapularis in Recurrent Anterior Dislocations of the Shoulder

Human cadaveric study of subscapularis muscle innervation and guidelines to prevent denervation

“…3,13,14 This muscle is commonly encountered during open shoulder surgery. Routine approaches involve splitting the muscle in line with its fibers or detaching it at the insertion.…”

Quantitative assessment of thinning of the subscapularis tendon in recurrent anterior dislocation of the shoulder by use of magnetic resonance imaging

“…4,8,9,12,20 Symeonides 19 and Gamulin et al 6 reported that the subscapularis was lengthened and showed significant healed posttraumatic lesions in recurrent anterior dislocation of the shoulder. Thus, shortening of the subscapularis tendon is an essential part of some of the operations for recurrent dislocation, such as the Putti-Platt procedure.…”

Subscapularis dysfunction following anterior surgical approaches to the shoulder

“…Depending on the position of the humerus, it acts as an important internal rotator, shoulder adductor and abductor, humeral head depressor, and active anterior stabilizer of the glenohumeral joint. 8,31,32,33,57 In addition, the SSC is the anterior part of the transverse force couple and, therefore, balances the external rotators of the shoulder and helps to compress and depress the humeral head into the glenoid cavity. Based on cadaveric, biomechanical, and electromyographic studies, different authors consider the upper and lower portion of the SSC muscle to be 2 separate units with independent functions and innervations.…”

“…53 It is believed that the SSC musculotendinous unit is lengthened and thinned in shoulders with recurrent anterior dislocations. 8,10,53,58 Tuoheti et al have shown that the SSC tendon undergoes an 18.7% decrease in thickness and a 29.1% decrease in cross-sectional area in patients with recurrent anterior dislocations compared to the contralateral side. 58 Repetitive stretching by the dislocated humeral head may cause the thinning and decrease in cross-sectional area of the SSC tendon.…”

“…The SSC is the most powerful muscle of the rotator cuff and plays a major role in optimal shoulder function. 8,31,32,33,57 In 1991, Gerber and Krushell reported a series of isolated tears of SSC tendon, directing attention to the problem of SSC insufficiency. 12 SSC dysfunction following open surgical exposure of the glenohumeral joint via SSC incision or tenotomy approaches has recently received increasing attention.…”