Hip dysplasia and congenital dislocation of the femoral head

Radiology
Unlike in infants, radiographs of pelvis show impor tant
features in this age group.The following radiological parameters should be noted.
Perkin’s line: This is a vertical line drawn at the outer border
of the acetabulum
Hilgenreiner’s line: This is a horizontal line drawn at the level
of triradiate cartilage
Shenton’s line: This is a smooth curve formed by the inferior
border of the neck of the femur with the superior margin of the
obturator foramen. This line is broken in DDH
Acetabular index: Normal value is less than or equal to 30°.
CE angle of Wiberg: The normal value is 15–30°.
The Hilgenreiner’s line and the Perkin’s line help to
assess the position of the femoral head. Normally, the
head lies in the lower and inner quadrant formed by these
two lines. In DDH, the head lies in the upper and outer
quadrant, the continuity of Shenton’s line is broken in DDH
(Fig. 35.22B). The acetabular index and the CE angle of
Wiberg help to assess the acetabulum.
In Adults
DDH in adults shows all the features seen in adolescents.
In addition, patient will have features of secondary
osteoarthritis of the hip namely—pain, stiffness, limp,
crepitus, restricted movements, etc.
Treatment
The aim of treatment in DDH is to achieve and maintain
an early concentric reduction to prevent future degenerative
joint disease. The methods to obtain reduction of the head
into the acetabulum vary according to the age groups.
Reduction can be obtained and maintained by Pavlik harness,
which was first described by Arnold Pavlik, in the former
Czechoslovakia, in the year 1958, von Rosen splints, and
other splints. Pavlik harness is the most important appliance
useful in this age group. This is the only harness that promotes
spontaneous reduction of a dislocated hip and maintains
the reduction, whereas other appliances only maintain
the reduction. Hence, Pavlik harness is called as “dynamic
flexion abduction orthoses.” This is useful in children less
than 6 months of age. Art from the reduction and the
immobilization, it allows active move ments in all directions
except extension and adduction. Nappies can be changed
easily. The success rate of this harness is 85–95 percent.
However, as the age advances, soft tissue contractures
develop along with secondary changes in the acetabulum,
which bring down the success rate of Pavlik harness. Complications include osteonecrosis and failure of reduction.