Author: Brian A Jacobs, MD, FACSM; Chief Editor: Sherwin SW Ho, MD more... Background Achilles tendon ruptures commonly occur to otherwise healthy men between the ages of 30 and 50 years who have had no previous injury or problem reported in the affected leg. Those who suffer this injury are typically "weekend warriors" who are active intermittently. Most Achilles tendon tears occur in the left leg in the substance of the tendoachilles, approximately 2-6 cm – the "watershed zone" – above the calcaneal insertion of the tendon. That the left Achilles tendon is torn more frequently may be related to handedness; right-handed individuals "push off" more frequently with the left foot. The most common mechanisms of injury include sudden forced plantar flexion of the foot, unexpected dorsiflexion of the foot, and violent dorsiflexion of a plantar flexed foot. Other mechanisms include direct trauma and, less frequently, attrition of the tendon as a result