In our daily lives, we are familiar with frozen shoulder. If the shoulder joint is painful or uncomfortable, it is thought to be caused by frozen shoulder, as if frozen shoulder is the highest incidence of shoulder disorders. In fact, rotator cuff injuries are the most prevalent shoulder disorder, followed by acromioclavicular impingement and shoulder instability, while the incidence of true frozen shoulder is relatively rare. According to the American Sports Medicine Association, frozen shoulder is actually a form of adhesive capsulitis and is a self-limiting disease. It is clear that there is still a great deal of bias in our understanding of shoulder disorders in our lives. Sometimes even orthopedic surgeons who are not trained in shoulder disorders may have the same misconceptions as laymen. Some patients may therefore delay treatment, which may even lead to functional disability of the shoulder joint and seriously affect their daily life. How to get out of the misunderstanding of frozen shoulder? The first step is to understand the shoulder joint from an anatomical point of view. The shoulder joint is a very complex joint. Simply put, it is a multi-axis ball and socket joint, consisting of the humeral head and scapular glenoid, with a large humeral head and a shallow scapular fossa, and the restrictions of the surrounding joint capsule are weak, making the shoulder joint the most mobile and flexible joint in the body. Some tendons end at the greater tuberosity of the humerus and wrap around the humeral head from the front, top and back of the shoulder joint to strengthen the stability of the shoulder joint; this tendon structure is called the rotator cuff tissue. An articular bursa covers the rotator cuff to reduce impingement friction between the rotator cuff and the rostral shoulder arch above it. Because of the high mobility of the shoulder joint, there exists an anatomical basis for susceptibility to shoulder joint disease. Second, we need to properly understand shoulder disorders. Statistically, the highest incidence of shoulder disorders is rotator cuff injuries, which account for 30-40% of shoulder disorders. Rotator cuff injury is a very common degenerative disease of the shoulder joint, and its occurrence is positively correlated with age. The symptoms of rotator cuff tear are similar to those of subacromial impingement syndrome, but they are also accompanied by shoulder abduction weakness. Athletes, those who lift heavy objects, and those who suffer from traumatic injuries are prone to rotator cuff injuries. Typical symptoms are pain in the neck and shoulder at night and pain in the arm when lifting; sometimes they are afraid to sleep on the affected side and even wake up with pain; the shoulder joint may be weak when abducting, lifting or posterior extension, and sometimes there are difficulties even in personal hygiene, which seriously affects the patient’s life. The acromion impingement syndrome is a condition in which the acromion and subacromial bursa tissues collide with the rotator cuff tissues during shoulder abduction and supination, resulting in shoulder pain and supination dysfunction. In general, impingement and rotator cuff lesions occur more often in older individuals and throwing athletes. Since repeated throwing motions may affect the rotator cuff attachment point, which is inherently low in blood supply, it is prone to rupture. The patient’s shoulder pain gradually worsens when throwing or lifting the armr. The pain often radiates to the proximal lateral and middle parts of the arm. If treatment is delayed, the patient may experience severe muscle atrophy and sleepless nights; if left to develop, the later stages may lead to rupture of important tendons in the shoulder joint, seriously affecting the patient’s function and life. The third most prevalent shoulder joint disorder is shoulder instability. Due to trauma or degeneration of the joint structure, as well as the high mobility and relatively poor stability of the shoulder joint itself, the shoulder joint is prone to dislocation or subluxation. The affected shoulder will produce pain, impaired movement, limited function, and in some cases, habitual shoulder dislocation. If left untreated, bone defects and joint surface destruction can occur, making later treatment difficult and in some cases, even tricky. The combined incidence of the first three diseases accounts for almost 70% or more of shoulder joint diseases. In addition to these, many other shoulder joint diseases exist, such as acromioclavicular arthritis, biceps tendonitis and calcific supraspinatus tendonitis. This makes periarthritis diseases account for a much smaller percentage of shoulder diseases. Frozen shoulder, in essence, is adhesive capsulitis. As you can see, when thinking that shoulder pain is frozen shoulder, we may have unknowingly gone into the misconception of shoulder joint disease. Shoulder disorders are complex and diverse, and taking them for granted may delay the best time for treatment.