SMR Stemless Reverse vs SMR Reverse Shoulder System

Inclusion Criteria: 1. Age ≥ 22 years of age 2. Skeletally mature as evident by scapula and proximal humerus closure 3. Candidate for primary total shoulder replacement in a grossly rotator cuff deficient joint with severe arthropathy (disabled shoulder), when clinical indications based on physical exam and medical history including one or more of the following: 1. Arthritis with rotator cuff tear not reparable 2. Irreparable rotator cuff tear 3. Rotator cuff tear arthropathy 4. Severe osteoarthritis and rotator cuff deficiency or stiff shoulder 5. Significant glenoid or socket side bone deformed or loss 6. Reoccurrence of instability or a chronic shoulder dislocation 7. Any other medical reason that the investigator determine that subject is a good candidate for a reverse total shoulder arthroplasty Exclusion Criteria: 1. BMI \> 40 kg/m2 2. Previous contralateral shoulder surgery within 3 months of enrollment or that requires active treatment (i.e. surgery or brace) 3. Had surgery in the targeted shoulder within last 12 months of enrollment, except diagnostic arthroscopy without procedures 4. Had surgery in lower limbs (such as hip or knee) within last 6 months of enrollment 5. Corticosteroid injections in the ipsilateral shoulder within 3 months of enrollment 6. Complete deltoid muscle insufficiency 7. Glenoid retroversion great than 25 degrees based off a 2D axial CT scan 8. History of/or signs and/or symptoms of local or systemic infection including but not limited to septicemia; osteomyelitis 9. Neurologically confirmed nerve lesion compromising shoulder joint function 10. Poor meta-epiphyseal bone stock compromising stability of the implant including but not limited to humeral head fracture, iatrogenic glenoid fracture, severe osteoporosis 11. Metabolic disorders which may impair fixation and stability of the implant including but not limited to uncontrolled diabetes mellitus with an HbA1C \> 7.5% 12. Extended bone loss after previous surgery defined as: complete bone loss of greater and lesser tuberosity 13. Meta-epiphyseal bony defect (including large cyst)