The severity of rotator cuff injury is mainly based on its symptoms, physical examination and MRI. 1. Symptoms: mainly pain, usually come to the doctor because of the pain, the pain is mild, the degree of injury may not be serious, if the pain is very severe, more common night pain, unable to sleep, affecting sleep or do movements, then it may be serious. 2. Physical examination: the interstitial pressure pain is more obvious, carry out a simple examination, check the muscle strength of the muscles around the shoulder joint, if the strength is weak, the mobility is poor (abduction, posterior extension difficulties), it can be judged to be more serious. 3. Magnetic resonance examination: Grade I rotator cuff injury usually has slight hemorrhage and edema, Grade II may show fibrosis, thinning or atrophy of tendon, and Grade III may have rotator cuff tear. If you have the above symptoms or are diagnosed with rotator cuff injury, it is recommended to follow the doctor’s instructions for standardized treatment as early as possible to reduce the adverse effects of the disease.