Inclusion Criteria:  Acute or chronic rotator cuff tear Small to medium sized rotator cuff tear Rotator cuff tear which can be treated with arthroscopic RCR (single or double row technique) Serum 25(OH)D levels < 30 ng/mL  Exclusion Criteria:  Massive rotator cuff tear that is inoperable or requires superior capsular reconstruction (SCR) Revision RCR Serum 25(OH)D levels ≥ 30 ng/mL Elevated serum calcium (> 10.5 mg/dL) Known or likely undiagnosed disorders of bone metabolism (i.e. Pagets, ostemalacia, osteopetrosis, OI, etc.) History of hyperhomocysteinemia Vitamin D allergy or other contraindication to Vitamin D supplementation Patients currently taking OTC multivitamin that contains Vitamin and unwilling/unable to discontinue use for the duration of this study Patient who are pregnant or plan to become pregnant in the next two years In the judgment of the investigators, patients who will have trouble adhering to the study follow-up schedule or dosing schedule