Weiner and Lipscom reported in 1956 that the incidence of closed Achilles tendon rupture was the third highest of all closed tendon ruptures in the body. In 1989, Jozsa et al. reported that Achilles tendon rupture accounted for 40% of all surgically treated tendon ruptures and was the first. (A) Etiology The exact cause of closed Achilles tendon rupture is not well understood. Many factors have an effect on Achilles tendon rupture. Zhang Jianzhong, foot and ankle surgery department, Beijing Tongren Hospital 1, tendon degeneration theory: due to the degeneration of the body, disease or trauma and other factors, damage the blood supply in the tendon, resulting in degenerative changes of the Achilles tendon. Under repeated stress, the Achilles tendon undergoes small tears, which cannot be effectively repaired due to reduced blood supply, and finally ruptures. 2, mechanical theory: the occurrence of Achilles tendon rupture is caused by the abnormal action of mechanical force. Other hormones, such as systemic or local use, can cause collagen fibers to develop poorly, reducing the strength of the Achilles tendon and increasing the risk of Achilles tendon rupture. 3, quinolone antibiotics have toxic effects on the Achilles tendon, can cause Achilles tendonitis, and finally can lead to Achilles tendon rupture. Such as pefloxacin can reduce the core glycoprotein production, thus changing the structure of the tendon and its biomechanical properties, making the tendon easy to fatigue rupture. 4. Other: some systemic diseases, such as ankylosing spondylitis, rheumatoid arthritis, gout, etc., can cause inflammation of the Achilles tendon and rupture under the action of external forces. It has been reported that the incidence of Achilles tendon rupture is higher in blood group O. Arner and Lindholm proposed three types of indirect injuries to the Achilles tendon: 1) when the knee is straightened and the forefoot is weighted, such as when starting to run or doing some jumping movements; 2) when the ankle joint is suddenly and unexpectedly dorsiflexed after a fall or slip; 3) when the plantar flexed ankle joint is suddenly and forcefully dorsiflexed, such as when falling from a height after jumping. Direct injuries are less common than indirect injuries, and can be closed or open injuries. Closed injuries often occur when the Achilles tendon is ruptured by a direct blow from an external force under low tension. Open injuries often occur when the Achilles tendon is under tension and is cut by a sharp object or crushed. Chronic tears of the Achilles tendon can be the result of an acute injury that is not diagnosed early or treated appropriately. It can also be the result of chronic inflammation following overuse syndrome and Achilles tendinitis. Partial ruptures or microtears of the Achilles tendon can also occur due to repetitive stresses and scar tissue can lengthen the Achilles tendon and cause weakness. Lea, Smith and Shields et al. reported that the sites of Achilles tendon rupture were 4%-14% at the musculotendinous junction, 72%-73% at the middle of the Achilles tendon, and 14%-24% near the heel bone attachment. (B) Clinical presentation and diagnosis Achilles tendon rupture mostly occurs in young and middle-aged men. The peak age of Achilles tendon rupture is 30-40 years old. The ratio of left to right is 1.2:1, with a slight increase on the left side. Bilateral ruptures are extremely rare. Patients usually have a history of trauma, such as suddenly hearing a sound in the heel during exercise, or feeling kicked from behind. After the injury, the patient feels pain in the heel, weakness in the lower leg, and limping. Later, the heel area gradually swells. Some patients have less pain or no swelling. Some patients may have a painless rupture. Other patients have symptoms such as localized pain and stiffness before the Achilles tendon rupture. If the injury is caused by a sharp instrument, an open wound may be seen in the Achilles tendon, and the Achilles tendon may be exposed. On examination, the patient with a closed injury may have weakness in plantar flexion of the affected ankle joint, and passive dorsiflexion of the ankle joint with increased mobility compared to the healthy side. A depression can be palpated at the rupture of the Achilles tendon, and there is obvious pressure pain. If the injury is prolonged and the local swelling is severe, the interrupted end of the Achilles tendon is not easily palpable. The ankle joint can still be partially flexed due to the integrity of the other flexor tendons. About 20% of patients are missed, resulting in delayed treatment. A positive Thompson’s test is useful for diagnosis. The patient is placed in a prone or kneeling position with the feet hanging off the edge of the bed, and the affected calf gastrocnemius is squeezed with the hand below the most extended part of the gastrocnemius muscle on the healthy side and the affected side, respectively. In patients with open injuries, the Achilles tendon rupture can be examined from the wound. X-rays: The significance of X-rays is twofold: one can identify concomitant fractures, and the other has some indirect signs on the lateral image that can assist in the diagnosis. For example, the border of the anterior heel triangle is not neat, the outline is deformed or even disappeared. Ultrasound: It has the advantages of being less expensive, rapid, reproducible and non-invasive. It can help the doctor to determine the gap between the Achilles tendon rupture, and provide a basis for choosing non-surgical treatment when the gap between the Achilles tendon rupture in plantar flexion of the ankle joint is small. However, ultrasonography requires a certain degree of skill and it is not easy to distinguish between a full or partial Achilles tendon rupture. MRI: It has good resolution of soft tissue, but it is expensive and is generally not used as a routine examination. (C) Treatment Acute closed rupture, non-surgical or surgical treatment has been controversial for many years. It is generally accepted that surgery should be performed on professional athletes, young patients, elderly patients with high functional requirements, and patients who have had an Achilles tendon rupture for more than one week. It has the advantage of lower re-rupture rate and more accurate restoration of the length of the tendon. As the tendon is repaired by surgery, the tendon can be subjected to certain stresses at an early stage, which is conducive to the reconstruction of collagen fibers and can restore muscle strength and prevent muscle atrophy more quickly. Early rehabilitation also makes the function of the tendon close to normal after the injury. Non-surgical treatment is suitable for the elderly, those who do not have high functional requirements, and those who do not want surgery. The advantages of non-surgical treatment are no surgical complications, no hospitalization, less cost, less overall recovery time than surgery, and acceptable functional results. However, non-surgical treatment does not allow for accurate tendon alignment, fibrous healing or tendon elongation, resulting in weakness. The re-rupture rate is higher. Non-surgical treatment The main principle of non-surgical treatment is to fix the foot and ankle in plantarflexion position with a cast or splint. However, there are different opinions on how long to immobilize, the position of the ankle when immobilized, and whether to use a long leg cast or a short leg cast. After 8 weeks, the cast was removed and replaced with a removable brace or cast with 2-2.5 cm heel padding. 2.Surgical treatment Surgical repair of Achilles tendon can be divided into three main categories: (1) direct suture. It is suitable for fresh closed injury or open injury. Incision or percutaneous closed suture. If the Achilles tendon defect is large and cannot be sutured directly, the proximal end of the Achilles tendon can be lengthened in a V-shape and then sutured. (2) Suture followed by repair with fascia and tendon, such as reinforcement with gastrocnemius fascia reversal or reinforcement with metatarsal tendon. This is suitable for the repair of old Achilles tendon rupture. (3) Replacement reinforcement with fascia, tendon or other biomaterials. For patients with large Achilles tendon defects. For example, the tendon is reconstructed with broad fascia, gastrocnemius fascia flap, short peroneal tendon, flexor hallucis longus tendon, flexor digitorum longus tendon, allograft Achilles tendon, etc. Some biosynthetic materials such as carbon fibers, Marles mesh, and Dacron graft materials have also been reported for repair of the Achilles tendon. Functional exercise after surgery depends on the quality of the Achilles tendon repair and the strength of the fixation. Akeson and Rasch proposed the concept of ‘Wolff’s law’ of connective tissue healing, which states that connective tissue heals in the direction of the stress applied. Amiel et al. suggested that this reduction in stress causes a decrease in fibroblast anabolism and an increase in catabolism, resulting in a decrease in collagen production and thus a weakening of the tendon. The extent to which this change occurs depends on the duration of the stress reduction. Other studies have shown that after mechanical stress is applied to the new tendon, the protofibers polymerize faster to mature collagen. Therefore, early postoperative activity is important to restore function to the Achilles tendon and to prevent joint stiffness and muscle atrophy. However, there is no surgical procedure that allows the patient to initiate active full range of motion and weight bearing immediately after suturing the Achilles tendon. Early activity has the potential to re-rupture the Achilles tendon, and a reasonable post-operative rehabilitation program needs to be developed.