Adequate upper limb function is critically important to maintenance of independence and prevention of disability in older adults. The goal of this work is to identify factors that contribute to rotator cuff rupture and improved outcomes for repair. Ultimately, the investigators seek to identify patients most at risk for rupture and to guide clinicians on optimal surgical and rehabilitation strategies. This pilot study will quantitatively characterize the morphological (muscle volume and fatty infiltration) and functional (shoulder isometric joint strength, movement when performing typical task) changes in the muscles of the rotator cuff following supraspinatus tear and surgical repair. The investigators hypothesize that patients with supraspinatus tear will have reduced muscle volume and increased fatty infiltration of rotator cuff muscles compared to their contralateral arm and age-matched controls, which will increase following surgery. The investigators further hypothesize that isometric joint strength in these individuals will be associated with muscle volume and the degree of fatty infiltration, and that older adults with a rotator cuff tear will use a restricted range of motion to accomplish functional tasks. This study emphasizes muscle function and composition with application to rehabilitation of upper limb function, which complements the theme of the Pepper Center.