The absence of the Achilles tendon may be caused by rupture of the Achilles tendon or inconspicuous Achilles tendon. 1. Achilles tendon rupture: the main function of the Achilles tendon is plantar flexion of the foot and flexion of the calf, which plays a role in fixation, and the causes of formation are divided into acute injury and chronic strain. (1) Acute injury usually has a history of trauma, when the calf is violently contracted or kicked, it will cause Achilles tendon rupture. (2) Chronic strain injury is common in athletes or patients with peritendonitis, due to long-term repeated pulling of the Achilles tendon, which can lead to congestion and edema of the surrounding tissues, hyperplasia and adhesion, peritendonitis is the precursor of Achilles tendon rupture. 2. The Achilles tendon is not obvious: due to congenital underdevelopment or acquired growth abnormality factors, it may lead to the short Achilles tendon is not obvious. 3. Fatty ankles: An inconspicuous Achilles tendon may also be due to excess fat in the ankle, resulting in the appearance of no Achilles tendon. There may be other reasons for the absence of the Achilles tendon. It is recommended to consult a doctor promptly to clarify the cause of the problem and take treatment under the doctor’s guidance.