Rotator cuff injury and frozen shoulder can be differentiated by the cause of the injury, the location of the pain, and the range of motion and treatment. 1. Pathogenesis: Most rotator cuff injuries have a clear history of trauma, with pain appearing suddenly after the injury, while rotator cuff injuries in the elderly may not have a clear history of trauma, and are mainly related to rotator cuff strain and degeneration. The complex causes of frozen shoulder are mostly chronic, with pain and activity limitation appearing gradually. 2. Pain location: rotator cuff injury mostly has obvious pain points, located in the front lateral shoulder joint. Rotator cuff injury has obvious pain arc, the pain is most obvious when the shoulder joint is abducted at 60~120 degrees, and the pain will be reduced when it is lower than 60 degrees or more than 120 degrees. Frozen shoulder has no fixed pressure point, mostly complaining of widespread pain around the shoulder joint. 3. Range of motion: when rotator cuff injury is passive, the range of motion of the joint is not obviously limited. Frozen shoulder will have obvious limitation of joint movement, and there will be obvious jamming sensation beyond a certain range. 4. Treatment: Most of the trauma-induced rotator cuff injuries can be recovered by suspension braking, and if the rotator cuff is broken, it can be repaired by arthroscopic surgery. Functional exercises are the mainstay of treatment for frozen shoulder. Shoulder pain is recommended to consult the doctor in time, do not delay the diagnosis and treatment.