The prevalence, classification, radiological and arthroscopic findings of intratendinous subscapularis tears.

PURPOSE

To investigate the clinical characteristics of intratendinous subscapularis (inSSC) tears.

METHODS

Retrospectively, 69 patients with arthroscopically confirmed inSSC tears were identified from 2018 to 2019. Preoperatively and at final follow-up, thorough physical examination was performed and clinical outcomes (American Shoulder and Elbow Surgeons [ASES] score; University of California, Los Angeles [UCLA] score; visual analogue scale [VAS] for pain; and Simple Shoulder Test [SST]) were recorded. Features of pre-operative magnetic resonance image (MRI) such as high signalling within the tendon substance, communication to the bicipital groove and long head of biceps tendon (LHBT) lesions were investigated. Characteristics of arthroscopic view were investigated. Bear-hug and internal rotation resistance test at 90° abduction and external rotation (IRRT90°) test were used to assess the SSC strength.

RESULTS

The mean follow-up was 2.4 (2-3) years. The prevalence of arthroscopically confirmed inSSC tears was 69/675 (10.2%) among arthroscopic rotator cuff repairs. Pre-operative physical examination found positive IRRT90° and bear-hug test in 41/60 (68.3%) and 42/69 (60.8%) patients, respectively. The Cohen kappa coefficient was interpreted to be substantial for the evaluation of all MRI parameters. According to the conditions of LHBT, inSSC tears were classified into 3 types: type I: without LHBT subluxation and tear; type II: with LHBT subluxation or tears and type III: with LHBT dislocation. At final follow-up, mean ASES, UCLA, VAS, and SST scores improved significantly from mean of 50.6 ± 14.7, 19.4 ± 3.07, 6.2 ± 2.0, and 6.1 ± 2.5 to mean of 90.7 ± 9.5, 32.2 ± 1.8, 1.4 ± 1.2 and 9.8 ± 2.2, respectively (P < 0.001). Bilateral symmetric strength was found by bear-hug and IRRT90° test in all patients postoperatively.

CONCLUSION

Understanding features of pre-operative MRI, physical examination and arthroscopic view is helpful to identify inSSC tears. Arthroscopic repair yielded satisfactory clinical outcomes in patients with inSSC tears.

LEVEL OF EVIDENCE

Level IV.