Inflammation of the growth plate of the calcaneus, the bone at the back of the heel, where the Achilles tendon attaches. Apophysitis calcaneus occurs mainly in older chil- dren and adolescents, especially active boys. It can be very painful, although it may be dismissed as "growing pains." Treatment includes activity limita- tion, medication, shoe inserts, heel lifts, and some- times casting if it becomes especially severe. Fortunately, it usually disappears as the child gets older. Also known as Sever condition.