Achilles tendon rupture. Illustration of a ruptured Achilles tendon. This is the most common tendon rupture injury and often results from over-exertion in sports. The Achilles tendon, also known as the calcaneal tendon, is the thickest and strongest tendon in the body. It connects the calf muscles to the heel bone (calcaneus). Treatment can either be by non-surgical means, such as using a cast to support the ankle while the rupture heals, or by stitching the ends of the tear back together.