Abstract. This paper investigates the relation between metaphyseal zone fragility and growth rate. It is concluded that there are two sites of weakness, the hypertrophic zone of the plate and the metaphysis. From a study of the age incidence of traumatic plate fractures compared with that of shaft fractures, it is deduced that fragility of both zones is a non-linear function of growth rate. It is concluded that this correlation explains the occurrence and age incidence of a range of diseases in which plate fractures occur in shear, and of central Schmorl's node which is a metaphyseal fracture in compression. The mechanism of plate fragility appears to be an increase in thickness of the hypertrophic zone from any cause, including rickets as well as increased growth. No evidence is found to implicate endocrine imbalance as a necessary factor in the normal transient fragility of the growth spurt.Key words: Growth plate --Bone growth --Plate fracture -Metaphysis Battered child --Epiphysidysis --Scheuermann's disease. rate, and to determine if possible which of the three mechanisms is the most likely.