When it comes to shoulder pain, many people may think of frozen shoulder first, but in fact, many diseases can cause shoulder pain and should not be confused with each other and delay treatment. Among shoulder disorders, the highest incidence is rotator cuff injury, followed by acromioclavicular impingement and shoulder instability. Statistically, rotator cuff injuries account for about 30-40% of shoulder disorders. Rotator cuff injuries (the tendon structure that wraps around the humeral head from the front, top and back of the shoulder joint to strengthen the stability of the shoulder joint is called the rotator cuff tissue) are a very common degenerative condition of the shoulder joint that occurs with a positive age correlation. 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 frequently in older individuals and throwing athletes. The repetitive throwing motion may affect the rotator cuff attachment point, which is inherently low in blood supply and therefore prone to rupture. The patient’s shoulder pain gradually worsens, with symptoms increasing when throwing or lifting the arm. 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 untreated, it may lead to rupture of important tendons in the shoulder joint at a later stage, 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 disorders accounts for almost 70% or more of shoulder disorders, in addition to many other shoulder disorders such as acromioclavicular arthritis, biceps tendonitis and calcific supraspinatus tendonitis. A common nearby site lesion is cervical spine disorders. There is considerable research that shows that patients with cervical spine disorders are at high risk of developing frozen shoulder, and that patients with frozen shoulder are often associated with a significant decrease in ipsilateral cervical lateral flexion and rotation. The cause of cervical spine disorders that cause frozen shoulder is not well understood, but may be due to pain in the shoulder and arm after spinal nerve root irritation or muscle spasm, or dysfunction of the nervous system due to cervical spine disorders, especially autonomic nerve strain. Other nearby diseases include heart disease, gallbladder disease, etc. Heart disease such as myocardial infarction and angina pectoris can sometimes radiate to the left shoulder and be misdiagnosed as frozen shoulder. Gallbladder diseases such as gallstones and cholecystitis can also be misdiagnosed as frozen shoulder when the pain radiates to the right shoulder. There are more clinical findings that show that patients suffering from neurological disorders such as hemiplegia and nerve numbness have a higher incidence of frozen shoulder. This is associated with decreased muscle strength and reduced movement, such as Parkinson’s disease, where the incidence of frozen shoulder is as high as 12.7%, and the cause of the high incidence is clearly related to reduced movement. Endocrine system diseases such as diabetes, hyperthyroidism or hypothyroidism are also closely related to frozen shoulder, especially in diabetic patients, where the incidence of frozen shoulder can be 10-20%. Thus, endocrine dysfunction is also one of the triggering factors of frozen shoulder. The diseases that cause shoulder joint pain can be said to cover several systems and their treatment methods are very different, so you should go to the relevant hospital for diagnosis and targeted treatment. Frozen shoulder is a very old concept, and with the development of the times, such an uncritical designation should gradually need to be replaced.