e child begins to walk, but sometimes the unusual breadth of the
pelvis, the presence of a lump in the buttock, snapping about the hip,
or a peculiar way of holding the limb, leads the parents to seek
advice early. In _unilateral cases_, when the child has learned to
walk at the late age of two, three, or it may even be four years, it
is noticed that the back is hollow and the buttocks unduly prominent,
and that there is a peculiar and characteristic limp; each time the
weight of the body is put upon the affected limb, the trunk makes a
sudden dip towards that side. There is no pain on walking. The
affected limb is shortened, as is shown by the projection of the great
trochanter above Nelaton's line; the shortening gradually increases,
and in time may amount to several inches. It is partly compensated for
by resting the affected limb on the balls of the toes and flexing the
knee on the sound side. The gluteal fold is shorter, deeper, and
higher than on the healthy side, and on account of the obliquity of
the pelvis the spine shows a lateral curvature, with its concavity to
the affected side. The movements at the hip-joint are free in all
directions except abduction; on practising external rotation it is
often found to be abnormally free; lastly, in young children, if the
pelvis is fixed, the head of the bone may be made to glide up and down
on the ilium.

_In bilateral cases_ the trunk appears well grown in contrast to the
short lower limbs, the hollow of the back is exaggerated, the abdomen
protrudes, the perineum is broadened, and the buttocks are unduly
prominent. The gait is waddling like that of a duck, the trunk
lurching from one side to the other with each step. In untreated cases
the deformity and disability become more pronounced as the capsular
and round ligaments are further stretched, the shortening and limp
become more marked, the patient is easily fatigued by walking or
standing, and is usually unfitted for earning a living. We have had
under observation, however, an adult male with bilateral dislocation
and extroversion of the bladder, who efficiently performed the duties
of a carrier for many years.

Except in fat infants, the _diagnosis_ is not difficult; the absence
of pain and tenderness, the freedom of motion and the absence of the
head of the femur from its normal position, differentiate the
condition from tuberculous disease of the joint, and from coxa vara
and other deformities in the region of