**2. Overview**

Subscapularis tendon tears have been firstly described by Smith [1] and Codman [2] Hauser reported in 1954 the first case of surgical repair of the subscapularis tendon [3].

Subscapularis tendon tears may be partial or full thickness. Chronic overload or acute trauma may cause tears. Traumatic tears are usually secondary to a forced external rotation or extension of the shoulder with the arm abducted. These tears are more prevalent in young patients as a consequence of a shoulder dislocation [4, 5]. In chronic tears due to repeated micro trauma degeneration, there is always an associated supraspinatus tear and biceps tendinosis or subluxation along with subscapularis tear. In tears of long duration, there can be severe retraction of the tendon underneath coracoids process. Sometimes it get tucked to superior capsule or glenohumeral ligaments forming a "Coma sign/tissue" as described by Burkhart [6].

**Figure 2.** Coracoid impingement.

The main causes for subscapularis tear with or without other lesions is Sub coracoid impingement with reduced coracohumeral distance. Due to repeated friction in narrow canal beneath the coracoids process, attritional tear of subscapularis happens. When this distance, which normally ranges from 8.7 to 11 mm, is lower than 5 mm, the risk that the subscapularis tendon is torn is high [7, 8].

The coracoid impingement may be primary or acquired. Primary causes of sub coracoid impingement are lateralized coracoid process, calcifications or ossifications of the subscapularis tendon, subscapularis muscle hypertrophy, and ganglion cysts. Secondary causes are usually traumatic or degenerative like displaced humeral or scapular fractures, non-unions, posterior dislocation of the sternoclavicular joint, spur formation, etc., (**Figure 2**).

The subscapularis tendon is torn in 63% of patients in whom the biceps tendon is sub-luxated or dislocated as there is continuity between medial margin of pulley and the subscapularis tendon.
