The osteochondroses compromise a group of entities characterized by involvement of the epiphysis, apophysis or epiphyseoid bone with radiographic findings of fragmentation, collapse and sclerosis suggesting osteonecrosis. Although some of these entities represent osteonecrosis, others are the sequela of abnormal stress and others represent normal development.

Kohler's disease involves the tarsal navicular and is rare. It is a self-limited disorder, difficult to distinguish from variations of normal ossification. When a child is symptomatic and radiographic findings of flattening and sclerosis are detected in a previously normal navicular bone, the diagnosis of osteonecrosis is more certain.

Scheuermann's disease represents a growth disturbance of the spine characterized by multilevel anterior vertebral body wedging, vertebral body endplate irregularities with Schmorl's node formation and increasing thoracic kyphosis. These changes are variable and most likely secondary to stress related intraosseous displacement of disc material (cartilagenous node formation) through cartilaginous endplates weakened on a congenital or traumatic basis. C. Incorrect. Kienbock�s disease represents osteonecrosis of the lunate seen in patients 20-40 years of age. D. Correct. Sever�s phenomenon represents normal ossification of the calcaneal apophysis.