_Morbid Anatomy._--In a true separation the epiphysial cartilage remains attached to the epiphysis. As a rule the epiphysis is not completely separated from the diaphysis, the common lesion being a separation along part of the epiphysial line, with a fracture running into the diaphysis (Fig. 8). It is not uncommon for more than one epiphysis to be separated by the same accident--for example, the lower end of the femur and the upper ends of the tibia and fibula. Epiphysial separations, like fractures, may be _simple_ or _compound_. Incomplete separations are liable to be overlooked at the time of the accident, but there is reason to believe that they may form the starting-point of disease. Strain of the epiphysial junction--the _juxta-epiphysial strain_ of Ollier--is a common injury in young children. _Clinical Features._--The symptoms simulate those of dislocation rather than of fracture. Thus, _unnatural mobility_ at an epiphysial junction may closely resemble movement at the adjacent joint, especially when the epiphysis is an intra-capsular one. The relationship of the bony points, however, serves to indicate the nature of the lesion. The degree of _deformity_ is often slight, because the transverse direction of the lesion, the breadth of the separated surfaces, and the firmness of the periosteal attachment along the epiphysial line often prevent displacement. In many cases a distinct, rounded, smooth, and regular ridge, caused by the projection of the diaphysis, can be felt. The peculiar "muffled" nature of the _crepitus_ is one of the most characteristic signs. The older the patient, and the further ossification has progressed, the more does the crepitus resemble that of fracture. Of the subsidiary signs, _loss of power_ in the limb is one of the most constant; indeed, in young children it is sometimes the first, and may be the only, sign that attracts attention. _Pain_ and _tenderness_ along the epiphysial line are valuable signs, particularly when the lesion is due to indirect or muscular violence and there is no bruising of soft parts. Localised _swelling_, accompanied by _ecchymosis_, is often marked; and the adjacent joint may be distended with fluid. As distinguishing this injury from a dislocation, it may be noted that in epiphysial separation there is no snap felt when the deformity is reduced, the tendency to re-displacement is greater, and the amount of relief given by reduction less than in dislocation. The use of the Röntgen rays at once establishes the diagnosis. _Prognosis and Results._--In the majority of cases union takes place satisfactorily by the formation of callus in the spongy tissue of the diaphysis and on the deep surface of the periosteum. In spite of the favourable nature of the prognosis in general, however, the friends of the patient should be warned that a completely satisfactory result cannot always be relied upon.