Pain in heel "“ usually when weight bearing. Adolescents aged 7-14 years, especially those who are active in sports. Overview The calcaneal tendon (achilles tendon) is the strongest tendon in the body, and it connects both the gastrocnemius and soleus, known as the calf muscles, to the calcaneus (heel bone) "“ the largest bone in the foot. An apophysis is a normal outgrowth of bone that usually forms an insertion point for a tendon or ligament. There are several apophyses throughout the body but, the one relevant to this condition is at the posterior section of the calcaneus (back of the heel bone). This is the point at which the calcaneal tendon inserts into the calcaneus. The suffix 'itis' denotes inflammation. An apophys'itis' is therefore inflammation at the apophysis. Sever's Disease is an apophysitis of the calcaneus, and is the most common cause of heel pain in growing young adults. Causes The calf muscles are used during activities like walking, running and jumping. Commonly, sports such as basketball, running and gymnastics cause the most heel cord loading and trauma to the apophysis. Around the age of 7, the calcaneal apophysis begins development of independent ossification (hardening), and usually completes around the age of 14. During growth spurts, bones become larger. As the bones develop, the muscles and tendons that are attached to them experience increased tension. In this case, the lengthening of the tibial bone in the lo