bly occurs
before puberty.

The following are the most common seats of separation in the order of
their frequency: (1) the lower end of the femur; (2) the lower end of
the radius; (3) the upper end of the humerus; (4) the lower end of the
humerus; (5) the lower end of the tibia; and (6) the upper end of the
tibia.

_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 ofte