This refers to the ossification disturbance in the ossification center during the developmental period of the bone resulting from interference of some factors. The disorder occurs in epiphysis, so it is also called osteochondritis or epiphysitis. The causative factors are trauma, diminished blood supply or genetic factor. Included are osteochondrosis of capitular epiphysis of the femur, epiphysis of the spine, epiphysis of the navicular bone, epiphysis of tubercle of the tibia, and epiphysis of tubercle of the calcaneus.