The intra-articular component of the subscapularis tendon: Anatomic and histological correlation in reference to surgical release in patients with frozen-shoulder syndrome

Recently, arthroscopic surgical techniques have been reported for release o f glenohumeral capsular contractures in selected patients with frozen-shoul der syndrome. The purpose of the current study was to assess the anatomy an d histology of the subscapularis muscle, including its intra-articular comp onent. Ten cadaveric shoulders underwent arthroscopy and dissection, and an additional 3 specimens underwent histological analysis. To provide clinica l correlation, 35 patients who underwent arthroscopic capsular release comp leted a modified questionnaire developed by the authors. The anterior-poste rior diameter and cephalad-caudad height of the intra-articular subscapular is tendon (IASS) averaged 5 mm and 11 mm, respectively This represented 83% of the sagittal diameter and 25% of the total height of the subscapularis at the point of release. Histological analysis confirmed these anatomic obs ervations. All patients had reduction of pain and improved function at an a verage of 22 months after surgery. Only 1 patient had mild subjective sympt oms of instability. The current study indicates that the IASS can be releas ed during arthroscopic capsular release for frozen shoulder with minimal ri sk of secondary anterior instability to the patient.