The purpose of this study is to examine bone-to-bone contact between the tuberosity as compared to a subacromial balloon spacer procedure. Using biplanar fluoroscopy to determine the three-dimensional (3D) motion of the shoulder compared pre-procedure to post-procedure, the investigators will be able to assess 1) the bone-to-bone contact of the tuberosity and acromion in the setting of a massive posterior superior rotator cuff tear 2) if the placement of a dermal allograft over the tuberosity does indeed decrease bone contact and 3) if the placement of a subacromial balloon spacer decreases bone-to-bone contact. Doing so will allow assessment of the relative contribution of the implant for arm elevation versus potential compensatory motion of increased scapulothoracic motion. The investigators will also be able to correlate this to patient-reported outcomes of pain and shoulder function.

Inclusion Criteria:

• Massive irreparable rotator cuff tear involving the supraspinatus and infraspinatus.
• No involvement of the subscapularis.
• Centered humeral head on X-ray examination.
• Primary complaint of pain.
• History of prior surgery, including failed rotator cuff repair.

Exclusion Criteria:

• Involvement of the subscapularis.
• Acromiohumeral distance less than 7 mm on upright anterior-posterior (AP) radiograph.
• Rotator cuff deemed repairable at the time of surgery.
• Patients younger than 65 years due to FDA clearance of the subacromial balloon spacer only for patients over 65