The purposes of this study were to investigate the relationship between partial thickness articular side tear of the subscapularis tendon and anterior internal impingement, and to evaluate the clinical outcomes.

We reviewed 27 cases who underwent surgery for tears in the deep surface of the subscapularis tendon. On arthroscopic examination, fraying or tear less than 10% thickness of the subscapularis tendon was observed in 9 cases, 10-30% in 5, more than 30% in 5, and longitudinal tear in 8. Tears were treated with debridement only in 21 cases, arthroscopic repair in 5, and open repair in 1. Labral or SLAP repair was also performed in 6 cases. Analysis was done by the preoperative clinical test, coracoid index and coracohumeral distance from the MR images, associated lesion and the presence or absence of anterior internal impingement on arthroscopic evaluation. Clinical results were assessed using the University of California at Los Angeles shoulder rating scale.

Anterior labral lesions were present in 59% of the cases. Hawkins test was positive in 16 cases (59%). Among these cases, labral lesions were seen in 14 (88%). The results were satisfactory in 81%.

We thought that anterior internal impingement between the partial thickness tear of the subscapularis tendon and the anterior glenoid labrum may cause shoulder pain and possibly induce progression of tear in deep surface of the subscapularis tendon, and Hawkins test is helpful for diagnosis. Satisfactory outcomes could be obtained with debridement or repair in partial tear of the deep surface of the subscapularis tendon.