Severs if a growth plate disorder of the heel bone, commonly occurring in active children aged 8-14. It is inflammation of the heel bone, caused by excessive stress/strain from the Achilles tendon and plantar fascia. Commonly pain is experienced when squeezing the heel.
When we are born, our heel is actually in 2 separate pieces, joined together by a growth plate. By the age of 14-16 the heel then fuses into one large bone. Treatment usually involves footwear modifications, heel lifts, exercises and sometimes the use of orthotics.
X-Ray of an adult, showing the heel bone which has fused