Sever's disease, also known as calcaneus apophysitis, is an inflammation at the back of the heel (or calcaneus) growth plate in growing children. The condition is thought to be caused by repetitive stress at the heel. This condition is benign and common and usually resolves when the growth plate has closed or during periods of less activity. It occurs in both males and females. There are a number of locations in the body that may get apophysitis pain. Another common location is at the front of the knee which is known as apophysitis of the tibial tuberosity or Osgood Schlatter's disease.