the hip. _Trendelenburg's test_
consists in noting the relative level of the buttocks when the patient
stands on the affected leg. Normally the buttocks remain on the same
level when the patient stands on one leg; in congenital dislocation
the buttock of the limb raised from the ground drops to a lower level;
in coxa vara it rises higher.

In paralytic conditions at the hip there may be considerable
resemblance to dislocation, but the muscles are slack and wasted, and
the normal attitude can easily be restored by pulling on the limb. The
most certain means of diagnosis is by the X-rays, which show the
position of the head of the bone in relation to the acetabulum, and
any torsion of the neck of the femur that may be present. This last
point is determined by taking a series of skiagrams in different
positions of the limb; these are also useful in correcting erroneous
impressions as to the angle of the neck of the femur.

_Treatment._--We are indebted to Paci, Schede, Calot, Lorenz, and
Hoffa for the rational treatment which seeks to reduce the dislocation
by manipulation.

#Reduction by Manipulation# (_Method of Lorenz_).--The child is
anaesthetised and placed on its back with the legs over the end of the
table. While an assistant steadies the pelvis, the surgeon pulls on
the limb so as to bring the trochanter down to Nelaton's line; this is
followed by forced rotation outwards and inwards and forcible
abduction to a right angle, and by kneading the adductors till they
are stretched and torn. The next step is to stretch the hamstrings,
and this is done by raising the foot, without bending the knee, until
the front of the thigh meets the abdomen, and the toes the face. To
stretch the anterior muscles, the patient is turned on the side or
face, and the hip is hyper-extended both in the straight and in the
abducted position. The stage is now reached at which attempts at
reduction may be made; the child is again laid on its back, the
surgeon grasps the knee, flexes the thigh to a right angle, rotates
laterally, and slowly flexes and abducts, while the thumb pushes from
behind on the trochanter, trying to guide and lift it over the rim of
the socket as the hip reaches the over-abducted position. Lorenz uses
a wedge of wood padded with leather about 3 inches high to rest the
trochanter upon while attempting to lift it forward. When reduction
takes place, there is generally a sound and a sudden jump, as in
reducing a trauma