PEMF as Adjunctive Treatment Following Surgical Repair of Full Thickness Rotator Cuff Tears

Inclusion Criteria: 1. Subject may be male or female between 21 years of age and 80 years of age at the time of consent. 2. Subject must have a repairable (≥1 and ≤ 5 cm in the AP direction) full thickness tear of either the supraspinatus tendon or both the supraspinatus and infraspinatus tendons, as determined by MRI and confirmed intra-operatively (pre-debridement) during the surgical repair of the rotator cuff using a calibrated probe. a. Subjects who do not meet this criterion will be considered screen failures. 3. This must be the first rotator cuff repair surgery on the study shoulder with the following exceptions: 1. Previous repairs of the teres minor and/or the subscapularis muscles are permitted. 2. Previous acromioplasties, decompressions, and clavicular fracture repairs are permitted. 3. Concurrent acromioplasties, subacromial decompressions and/or distal clavicular excisions are permitted. 4. Concurrent fracture repairs or reconstructions are NOT permitted. 5. Biceps tenodesis or tenotomy (open or closed) are permitted. 4. Subject must not have used NSAIDs for one (1) week prior to surgery. 5. Subjects must agree NOT to use NSAIDS suring the first 6 weeks of the study. Low dose aspirin (81 mg) is permitted. 6. Subject must be willing and able to participate in post-operative physical therapy exercises. 7. Subject must be willing and able to follow all study procedures and return for all study visits. 8. Subject must have reliable access to any iOS device using iOS v.9.3 or later or an Android device with WiFi access for downloading the free device-specific app. 9. Subject must understand and be willing to sign the IRB-approved Informed Consent Document. Exclusion Criteria: 1. Subject has a tear \<1cm or \>5cm in size measured intraoperatively, pre-debridement, using a calibrated probe. a. Subjects who do not meet this criterion will be considered screen failures. 2. Subject has a BMI \> 45. 3. Subject has a pacemaker or defibrillator. 4. Subject is not able to or is unwilling to have an MRI on the study shoulder. 5. Subject requires assistive devices to walk such as crutches or walkers. 6. Subject has a rotator cuff tear in which the subscpularis tendon requires repair. a. Biceps tenodesis or tenotomy (open or closed) is allowed. 7. Subject has a Fuchs score grade of 3 for fatty infiltration on any of the rotator cuff muscles. Grade 1: Normal muscle, no or some fatty streaks Grade 2: Moderately pathologic muscle; more muscle than fat Grade 3: Advanced degeneration; as much muscle as fat or less muscle than fat 8. Subject has moderate to severe arthritis based on preoperative imaging or as judged at the time of arthroscopy. 1. Pre-operative x-ray findings consistent with Grade 3 or Grade 4 glenohumeral arthritis, where the grades are defined as follows: Grade 1: doubtful narrowing of joint space and possible osteophytic lipping; Grade 2: definite osteophytes and definite narrowing of joint space; Grade 3: moderate multiple osteophytes and definite narrowing of joint space and some sclerosis and possible deformity of bone contour. Grade 4: bone on bone morphology 2. Intra-operative exposed subchondral bone involving \>= 50% of either the humeral head, glenoid or both. 9. Subject has a known collagen disorder such as, but not limited to, osteogenesis imperfecta (OI) or Ehlers-Danlos syndrome (EDS). 10. Subject has a known inflammatory or autoimmune connective tissue disease such as, but not limited to, gout affecting the shoulder, scleroderma, SLE, rheumatoid disease, or calcific tendonitis of the shoulder. 11. Subject has a metabolic bone disease such as Paget's disease or osteomalacia. a. Subjects with osteoporosis are not excluded from the study. 12. Subject has a deltoid defect, deltoid palsy or any other pseudoparalysis. 13. Subject has HIV, hepatitis, or has had an active malignancy in the past 5 years. 14. Subject has had previous rotator cuff repairs or repairs of the labrum. a. See Inclusion Criterion #3 for permitted surgeries. 15. Subject has a diagnosis of fibromyalgia or other chronic pain syndrome. 16. Subject has shoulder pain of unknown etiology. 17. Subject has an active or on-going neoplastic disease, except for benign skin cancer(s). 18. Subject has undergone administration, within the last 30 days, of any type of corticosteroid (with the exception of asthma medications and ophthalmic medications), antineoplastic, immunostimulation or immunosuppressive agent. 19. Subject is septic or has a local or systemic infection. 20. Subject has an admitted active substance abuse problem which includes recreational drugs and/or narcotics or a history of substance abuse where history is defined as "not under the care of a physician" for more than 5 years. a. Prescriptive medical marijuana is not permitted, including CBD oils. 21. Subject consumes more than 14 (men) or 7 (women) standard drinks (alcoholic units) per week where a drink equals a 12 oz. beer, or a 5 oz. glass of wine, or a 1.5 oz. shot of liquor. 22. Subject is currently seeking or receiving worker's compensation for this injury or for an injury that has occurred more than12 months prior to enrollment in this study or subjects who are currently in litigation or who have a history of litigation related to musculoskeletal diagnoses. 23. Subject has a major mental illnesses including major depression, bipolar disorder, schizophrenia or dementia that would prevent them from following the protocol and/or independently completeing the patient reported outcomes measures. 24. Subjects who have coexistent cervical spinal pathologies such as radiculopathies or myelopathies. 25. Subject has a mental or physical condition that would prevent tem from complying with the study protocol. 26. Subject has any other condition that, in the opinion of the investigator, would prevent them from completing the study. 27. Subject is a prisoner. 28. Subject has participated in another clinical trial within the last 90 days. a. The last study visit attended by the subject starts the 90 day window.