12
The Bulletin
hip health, cont.
whereas the complementary dynamic images give information on
the stability of the hip joint. The accuracy of hip ultrasonography is
limited by the experience and skill of the operator, especially when
performed within the first 3 weeks of life, and so is best performed
in centers with significant experience.
Thus, ultrasonography is the technique of choice for screening
infants with risk factors for DDH up to age 4 months of age (ideally
between age 6 to 12 weeks) and is useful in following the results
of intervention. Ultrasound images in neonates often reveal minor
degrees of dysplasia that usually resolve spontaneously and may
lead to overtreatment of physiological hip variations. Of the ultra-
sounds showing mild dysplasia at birth, 77 percent normalize when
repeated at 4 weeks and 90 percent do so by 9 weeks of age.
In the preterm child, routine ultrasound screening of the stable hip
with risk factors (or the unstable hip that stabilizes spontaneously)
should be performed at chronologic age rather than corrected
age. Breech presentation in the premature infant does not cause
the same level of intrauterine constraint and restriction as it does
in term infants. Studies indicate that prematurity reduces the asso-
ciated risk of DDH in breech presentation.
After age 4 months, the femoral head is ossified, and thus the gold
standard imaging modality transitions to the AP pelvic radiograph.
Note that hip radiography, unlike ultrasonography, should be
performed at an adjusted age to allow normal ossification assess-
ments and better visualization of the femoral head.
Treatment
Treatment of DDH is dependent on the age at presentation. For
children 0 to 6 months of age, a reducible hip is treated in a Pavlik
harness or other appropriate orthosis. Patients with modest ultraso-
nographic abnormalities but a stable hip exam can be monitored,
as normalization can be expected without treatment.
The Pavlik harness is a dynamic orthosis that allows the infant to
actively move the hips through a sphere of motion that encourages
deepening and stabilization of the acetabulum. The harness is applied
as soon as possible after the diagnosis of DDH is made. The length of
treatment is dependent on age at presentation. Progress is judged by
serial physical examinations and static and dynamic ultrasonography.
In the case of a frankly dislocated hip, treatment is abandoned if no
improvement is noted within 4 weeks of splint application. Closed
reduction under general anesthesia, usually with arthrographic
evaluation and subsequent spica casting, is then attempted at 4 to
5 months of age. For a persistently irreducible dislocation, which is
unusual in the 0- to 6-month age group, open operative reduction
of the hip with subsequent spica casting is undertaken.
As alluded to earlier, the success of Pavlik harness treatment is vari-
able and correlates with the severity of the hip dysplasia. Treatment
is successful in nearly 100 percent of stable hips, greater than 90
percent in dislocatable (Barlow positive) hips, 61 percent to 93
percent in dislocated but reducible (Ortolani positive) hips, and as
low as 0 percent in irreducible, fixed dislocations.
The length of treatment is dependent on the age at presentation
and improvement of standard measurements on imaging. The older
the infant, the longer the required treatment. Progress is judged by
serial physical examinations, static and/or dynamic ultrasonography,
or serial AP pelvis radiographs in patients older than 4 months.
Treatment is terminated when the physical exam and the imaging
normalize. Acetabular remodeling has been shown to benefit from
orthoses up to 15 months of age.
When a fixed dislocation is present or no improvement is made with
Pavlik harness management after 4 weeks, closed reduction under
general anesthesia with arthrographic evaluation and subsequent
spica casting are attempted at 4 to 5 months of age (adjusted age
for premature infants). For hips not amenable to closed reduction,
open operative reduction of the hip with spica casting and often an
adductor tendon tenotomy are required. Early, successful manage-
ment reduces the risk for future operations such as pelvic osteoto-
mies or early total hip replacement.
After 18 months of age, operative treatments are the mainstay of
DDH management. In younger children, up to age 6 to 8 years,
prophylactic surgical reconstruction is still entertained. While some
hips may be amenable to closed reduction, most will need surgery.
We have found that after 12 months of age, there is a dramatic
drop-off in the ability of the acetabulum to remodel. In this case,
pelvic osteotomy is required. Approximately one-third of patients
presenting with a dislocated hip after 18 months of age will require
a hip replacement by age 40. For untreated DDH in adolescence,
and certainly through adulthood, treatment is guided by symptoms.
On average, patients with significant residual hip dysplasia require
“joint preservation surgery” typically by their mid 20s. For those with
The Pavlik harness is a
dynamic orthosis that
allows the infant to
actively move the
hips through a
sphere of motion
that encourages
deepening and
stabilization of the
acetabulum.
