Various treatment options have been attempted as non-surgical methods for treating rotator cuff tears, but the treatment method for structure restoration of the torn tear is still limited. Several animal and clinical studies reported that atelocollagen positively affects the structural restoration between the rotator cuff tendon and bone. On the other hand, there is no evidence that an atelocollagen injection into the subacromial space is helpful in the structural recovery of a rotator cuff tear. Therefore, excessive use of atelocollagen should be avoided.