Tennis elbow, also known as humeral epicondylitis, is a common clinical condition that is characterized by pain in the lateral aspect of the elbow when the patient grips and lifts objects with force. According to statistics, epicondylitis occurs in 10%-50% of tennis players; it can also occur in people who engage in repetitive and inappropriate force activities over a long period of time. It has been found that epicondylitis of the humerus is actually a degeneration of the tendon of the short extensor carpi radialis (ECRB) or the extensor digitorum communis (EDC), rather than a result of local inflammation. Moreover, the finding of neuropeptides at the radial short extensor carpi radialis suggests that neuroinflammation may be one of the reasons why patients present with pain in the lateral part of the elbow joint. Etiology The most common cause of tennis elbow is a tendon injury caused by repetitive forceful pulling of the forearm extensors, which occurs in patients between 35 and 50 years of age. Young or professional tennis players are at increased risk of developing tennis elbow due to overuse of the elbow joint. Some researchers suggest that tennis elbow may be caused by a failure of repair after tendon injury and local vascular damage. Normal tendon repair can be interrupted by subsequent injury, while damaged tendons continue to impede tendon repair. prof. Cyriax believes that the muscle-bone junction is the most susceptible to injury because the tendon fibers there are relatively unsupplied with blood. Clinical manifestations and physical examination The main manifestations include pain in the lateral aspect of the elbow joint, which may radiate to the forearm and may be aggravated by gripping or lifting with the affected limb. Physical examination should include an examination of the cervical spine, as pain caused by nerve root compression at C5-C6 or C6-C7 can be misdiagnosed as humeral epicondylitis. Patients can be observed for lateral elbow pain by moving the cervical spine and performing the Spurlings test. The stability of the scapula is important for tennis pumping, and without a stable point of force for the rotator cuff muscles, the function of the shoulder joint will be significantly limited. Thus, when a tennis player does not have enough shoulder strength to make a single draw, he uses the extensor muscles, which leads to overuse of the extensor muscles and degenerative tendon degeneration. Palpation of the lateral epicondyle of the humerus reveals tenderness and pressure pain in the lateral epicondyle and anterior aspect of the forearm. Pain in the lateral epicondyle of the humerus can occur with the wrist joint extended in elbow extension and forearm rotation anteriorly or with the wrist joint fully flexed In addition, patients often have decreased grip strength due to pain in the lateral epicondyle of the humerus, which is a stable and sensitive diagnostic indicator of tennis elbow, so grip strength of the affected limb is also measured by a hand-held grip strength meter. Neurological considerations Diagnosing tennis elbow also requires consideration of symptoms caused by abnormalities in the nerve structures, such as radial nerve entrapment syndrome and posterior interosseous nerve compression that can cause pain in the lateral 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. When deep pressure pain in the radial head and limitation of forearm rotation posteriorly occurs, it indicates radial nerve injury, while pressure pain in the humeral epicondyle and limitation of wrist extension suggest that the patient has tennis elbow. The posterior interosseous nerve may be compressed at the point of entry into the posterior rotator muscle. Conservative treatment Nirschl et al. divided conservative treatment into three phases, based primarily on 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 ultrasound therapy, ultrasound drug penetration therapy, electrical stimulation, iontophoresis, heat therapy and cryotherapy. Manipulative 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. Some researchers suggest that tennis elbow can be treated by stretching the wrist extensors and forearm muscles, with the wrist joint as if it were supported with the top cocked up, or by stretching with a reverse force. Functional exercises Muscle strength and flexibility training can be effective in treating tennis elbow, with centrifugal strength training considered to be the most effective method. It restores strength to the tendon by mimicking the production of collagen by mechanoreceptors that help the tendon recover, and also improves the collagen queues in the tendon and stimulates the formation of collagen cross lines, thereby increasing the tensile strength of the tendon. Centrifugal strength training begins by immobilizing the forearm with the elbow and wrist in the extended position and making a fist. The patient uses the opposite hand to lower the affected wrist joint and then raises it to the original position. Each set is repeated 5-15 times for a total of 3 sets and is recommended to be done daily. It is normal to experience mild discomfort during training, but if the pain is severe, stop training immediately. Once the patient can easily complete the training, the resistance can be increased by adding gravity or rubber bands. Platelet Plasma Concentrate If the above methods do not provide good results, platelet plasma concentrate (PRP) injections are recommended.PRP contains cell growth factors and cytokines that promote proliferation, differentiation, and maturation of human cells.A multicenter study by Mishra et al. found that patients in the PRP injection group had significant pain relief compared to the group with restricted wrist extension, reducing pain symptoms by improving microvascular circulation in the tendon and surrounding muscle tissue. This reduced pain symptoms by improving microvascular circulation in the tendon and surrounding muscle tissue. When conservative treatment of tennis elbow fails, surgical options include incisional debridement and repair or simple debridement, percutaneous decompression, and arthroscopic debridement. Regardless of the surgical approach chosen, the principle of surgical treatment is the same: removal of degenerative tissue at the radial short extensor carpi radialis (and the common extensor tendon if involved). In general, the majority of patients with tennis elbow showed significant postoperative symptomatic relief, and Nirschl et al. followed 130 patients with tennis elbow who underwent incisional debridement for up to 10 years, showing that 97% of patients showed significant symptomatic improvement and 93% returned to their pre-morbid level of motion. In contrast, Thorton et al. used a modified surgical technique of Nirschl to fix the repaired tendon to the lateral epicondyle of the humerus with suture anchors, and the patient’s grip strength was well restored after surgery. Arthroscopic debridement for tennis elbow can be equally effective and can also address intra-articular lesions, as Szabo et al. found that 44% of patients had a combination of intra-articular lesions. Another advantage of arthroscopic treatment is the short return to work time (11 days on average). There have been many studies comparing the efficacy of the two surgical approaches. Solheim et al. followed 300 patients with tennis elbow for 3-6 years, and although both groups had a good clinical prognosis, the mean shoulder, arm, and hand dysfunction scores (QuickDASH, Disabilitiesofarm,shoulder&hand) were higher in the arthroscopic group. The same results were obtained in the Peart et al. study, and the return to work was shorter in the arthroscopic group. Excessive debridement can damage the lateral collateral ligament of the elbow joint leading to posterior lateral rotational instability. The lateral collateral ligament can be well protected during arthroscopic debridement by keeping the lateral collateral ligament parallel to the superior half of the radial head. Complications such as heterotopic ossification and paralysis distal to the incision have also been studied. Surgical Technique The patient is placed supine on the operating table with the affected limb abducted on a special surgical table for the hand and the scapula padded. A tourniquet is tied around the upper arm and a sterile towel is placed. An esmarch tourniquet is applied first to expel the blood and then inflate the tourniquet. A 2-3 cm incision is made anterior to the lateral humeral epicondyle distally, and a plane is visible with the long radial carpal extensor muscle at the anterior border and the common extensor tendon at the posterior border. The long radial carpal extensor muscle is separated anteriorly so that the underlying short radial carpal extensor muscle can be exposed. Since the degenerative tissue is light gray in color, it is easily distinguished from healthy tendon tissue, so complete excision of the diseased tissue is not difficult. In addition, the scratchtest (scratch test) can be used to determine whether the debridement is complete. A small suture anchor is then inserted into the lateral epicondyle of the humerus to thoroughly flush the surgical area of bone debris to avoid heterotopic ossification. The repaired radial short extensor carpi radialis is secured to the external epicondyle of the humerus with a suture anchor. Finally, the wound is closed layer by layer, and posterior lateral splinting for one week is sufficient.