Older age, larger tear size, female sex, and non-traumatic tears were independently associated with reduced shear wave velocity of the supraspinatus tendon postoperation. The findings of our study correlate to cohort studies assessing the influence of these variables on rotator cuff retear rates, suggesting that the mechanical stiffness of the supraspinatus tendon, as assessed by shear wave elastography, may have an important association with a successful repair.