The shoulder joint is the most flexible joint in the body, but this high degree of flexibility comes at the expense of some stability. Several bones and their connecting soft tissues (muscles, ligaments, tendons) work together to produce the motion of the shoulder joint. These components interact with each other within the limits of maximum motion to maintain the integrity of the shoulder joint. Each component of the shoulder joint contributes to the motion and stability of the shoulder joint. Certain tasks or sports are extremely demanding on the shoulder joint, and when the limits of shoulder motion are exceeded or excessive forces are applied to one component, a shoulder injury will result. Many patients experience shoulder pain and are often thought of as having “frozen shoulder” when they talk to friends or go to the hospital. In fact, the concept of “frozen shoulder” encompasses many diseases, some of which are treated very differently, so the concept of “frozen shoulder” has been gradually abandoned internationally. Among the many diseases that cause shoulder pain, one of the most common is rotator cuff impingement or subacromial impingement syndrome. Shoulder injuries are more common in young people, athletes and the elderly. Especially in the elderly population, there are many causes of shoulder pain. Rotator cuff impingement or subacromial impingement syndrome occurs when the rotator cuff tendons and subacromial bursa are compressed in the narrow space under the acromion, which is often referred to as “frozen shoulder” in the elderly. This results in swelling and inflammation of the rotator cuff tendons and subacromial bursa. This compression is more severe when the arm is lifted off the torso and the symptoms are most pronounced. Minor rotator cuff injuries can develop over time into rotator cuff impingement, and repetitive motion of the shoulder joint can also lead to inflammation of the subacromial bursa. As we get older and develop arthritis, bone spurs can form on the acromion, further narrowing the subacromial space. Rotator cuff impingement is more common in older adults who play sports or work in an overhead position. Calcium deposits in one of the rostro-capital ligaments can also lead to spur formation. Therefore, the treatment of frozen shoulder generally includes conservative treatment and surgical treatment. Usually, the conservative treatment for frozen shoulder is to promote local blood circulation, accelerate the absorption of exudate, and promote the repair of diseased tissues. It is also used to strengthen the rotator cuff tendons, restore the mobility lost due to pain and inflammation by pulling, and restore the position of the humerus under the acromion to a better state to reduce the compression of the bursa. Usually short wave and magnetic therapy in the rehabilitation medicine department are very effective in the early treatment of “frozen shoulder”. Surgical treatment can be accomplished through minimally invasive shoulder arthroscopy, but it is up to the physician to evaluate, examine, and rule out the presence of other pathologies. Therefore, it is important for clinicians to pay attention to rotator cuff impingement as a cause of shoulder pain and to make a clear diagnosis and treatment plan for the patient. Patients with shoulder pain should not just put on the “frozen shoulder” label, but should actively go to a regular hospital to receive treatment.