An RCT to Compare the Outcomes of Patients With Large Rotator Cuff Repair That Undergo Repair With or Without SIS

Inclusion Criteria: Patients with large rotator cuff tears (Type 1B or Type 2) determined by clinical examination and diagnostic imaging. Criteria described by Harryman et al (1991) will guide the classification of rotator cuff tears defined and reassessed at the time of surgery (Type 0 = intact cuff, Type 1A = thinned cuff or partial thickness defect, Type 1B= full thickness defect on one tendon, Type 2 = full thickness defect of two tendons, Type 3 = full thickness defect of three tendons). Exclusion Criteria: Previous shoulder surgery, excluding acromioplasty or diagnostic arthroscopy. Inability of the surgeon to repair the tear with remaining defect no greater than 10mm in diameter, Inability of the surgeon to repair the tear with less than 1cm of medialization, Evidence of other significant shoulder pathology including, Type II-IV SLAP lesion, Bankart lesion, Hill Sachs lesion, Grade III osteoarthritis). Active joint or systemic infection, Significant muscle paralysis of the shoulder girdle, Major medical illness that would preclude undergoing surgery, Patients who are unwilling or unable to be assessed according to study protocol for one year following surgery Major psychiatric illness, developmental handicap or inability to read and understand the English language