Lateral epicondylitis of the humerus, also known as lateral elbow pain syndrome, is commonly known as tennis elbow. The main clinical manifestation is pain in the lateral aspect of the elbow joint, which can be aggravated by forceful fist clenching and forearm rotation and elbow extension movements (such as towel twisting, floor sweeping, etc.), and multiple local pressure pains without abnormal appearance. Humeral epicondylitis is a painful condition of the soft tissue around the humeral epicondyle caused by acute and chronic injury. The disease is occupationally related and is most common in adults who need to repeatedly extend their wrists, especially those who frequently rotate their forearms, such as tennis players (tennis players often swing the backhand to hit the ball, which often leads to the disease if not properly), violinists, and carpenters. It is very common in clinical practice and is one of the most common conditions seen in pain clinics. The pain originates from the posterior lateral aspect of the elbow, and increases when the posterior rotator muscle moves, such as forceful gripping and controlling, and radiates to the forearm, with limited pressure pain at the lateral humeral epicondyle. In the acute phase, rest and braking should be applied for 1-2 weeks. The majority of the disease can be cured by non-surgical treatment, and a very small number of people with ineffective treatment and greater pain can be considered for surgical release treatment. Etiology: 1. The most common cause of tennis elbow is tendon injury caused by repeated forceful pulling of the forearm extensors, which is particularly likely to occur in patients aged 35-50 years; 2. Some researchers have pointed out that tennis elbow may be caused by failure of repair after tendon injury and local vascular injury. Normal tendon repair can be interrupted by subsequent injury, while the damaged tendon continues to disrupt tendon repair; 3. Special populations: tennis players are prone to tennis elbow for both intrinsic and extrinsic reasons. The extrinsic cause is the use of an overly heavy racket or a handle that is too small resulting in incorrect forces acting on the extensor digitorum generalis tendon. The intrinsic cause is the chronic accumulation of microtrauma to the relevant tissues caused by the excessive use of the wrist joint during the player’s backhand stroke. Concomitant symptoms: Diagnosis of tennis elbow also requires consideration of symptoms caused by abnormalities in the nerve structure, such as radial nerve entrapment syndrome and posterior interosseous nerve compression can cause pain in the lateral aspect of the elbow joint. One study found that 5% of patients with humeral epicondylitis may have radial nerve compression because deep branches of the radial nerve pass behind the Frohse arch along the edge of the posterior rotator muscle fibers. Deep pressure pain at the radial head and limitation of posterior rotation of the forearm indicate radial nerve injury, while pressure pain at the humeral epicondyle and limitation of wrist extension suggest the presence of tennis elbow. The posterior interosseous nerve may be compressed at the point of entry into the posterior rotator muscle. The pain of this type of nerve entrapment sign is more diffuse, whereas in tennis elbow the pain is concentrated in the forearm muscles distal to the lateral epicondyle of the humerus. Limited extension of the middle finger in elbow extension helps to differentiate neurologic disease, but the presence or absence of radial short carpal extensor muscle involvement must be determined. In addition, the cervical nerve roots need to be evaluated for compression. Localized trigger points or chronic muscle spasm in the neck can also cause tennis elbow patient-like pain. One study suggests that severe chronic cervical nerve compression can result in a negative repeat strength test of the carpal extensors. Conservative treatment: Nirschl et al. divided conservative treatment into three phases, primarily the acute inflammatory phase, the chronic inflammatory phase, and the muscle strength deficit phase. There are more conservative treatments, ranging from those aimed primarily at symptom relief to etiologic treatment. However, due to individual differences, there is still no uniform standard of treatment. The first thing that is carried out is health education of the patient and correction of wrong activity patterns. The common conservative treatments for tennis elbow are heat therapy, cryotherapy, and shock wave therapy. And manual therapy can also be used to treat tennis elbow, such as moving the affected limb or massage. In addition, active muscle strength restoration programs such as wrist extensor restoration should be done in conjunction with scapular and rotator cuff muscle group restoration exercises. Some researchers have suggested that tennis elbow can be treated by stretching the wrist extensors and forearm muscles, with the wrist joint acting as if it were supported and cocked at the top, or by stretching with a reverse force. Shock waves are now more popular internationally for the treatment of sports injuries to soft tissues such as muscle tendons. Shockwave treatment for tennis elbow has achieved good results internationally as well as with domestic professional sports teams. It is a non-invasive treatment modality. In the treatment, shock wave can make the humeral epicondyle tendon stop point of micro-injury and then repair, promote tissue regeneration, capillary and epithelial cell renewal. It can effectively relieve pain, prevent recurrence and treat both the symptoms and the root cause. Surgical treatment: When the conservative treatment of tennis elbow fails, the surgical treatment options are: muscle release, radiofrequency treatment under ultrasound, and triple oxygen ablation. Regardless of the surgical method chosen, the principle of surgical treatment is the same: to improve the degenerated tissue at the radial short extensor carpi radialis (if the common tendon of the extensor muscle is involved, it should also be treated).