Ruptured Achilles tendon. Coloured doppler ultrasound scans of sagittal (left) and transverse (right) sections through the ankle of a patient with a ruptured Achilles tendon. The Achilles tendon is the largest and strongest tendon in the human body. It connects the heel bone to the calf muscles. It may be injured during exercise, or by a trip or fall, resulting in pain and swelling. Treatment is rest and physiotherapy, although in extreme cases surgery may be needed.