Development dysplasia of the hip (DDH) is a condition caused by abnormal development and morphology of the acetabulum and by increased ligamentous laxity around the hip,
including a wide spectrum of abnormalities affecting the proximal femur and acetabulum (that range from instability,
dysplasia,
variable degrees of subluxation to an established dislocation).
DDH is a very frequent condition,
being the most frequent congenital musculoskeletal pathology,
with an estimated incidence of 2-20:1000.
DDH occurs more frequently in healthy individuals,
but there is a higher prevalence in some syndromes.
The etiology of DDH is multifactorial and raises some controversy.
Genetic predisposition / family history,
fetal breech presentation,
female gender and Caucasian race are accepted as the main risk and predisposing factors.
There is also an association between DDH and large babies,
first borns,
history of oligohydramnios and with postnatal positioning.
In most cases,
DDH is unilateral,
being more frequent in the left hip.
It is believed that this difference is explained by the most common uterine fetal position,
in which the left hip is attached to the mother's spine,
limiting or preventing its abduction.
In about one third of patients,
DDH is bilateral.
Early diagnosis of DDH is essential because treatment is generally easy and inexpensive,
greatly reducing the need for further surgical intervention and the development of degenerative joint disease in adult life.
Thus,
all newborns should be screened through the maneuvers of Barlow and Ortolani during the physical examination.
When these are positive or suspect,
ultrasound of the hips should be performed to establish or to deny the diagnosis of DDH.
The baseline changes in DDH are the immaturity of acetabular development and / or the increased laxity of the ligamentous structures of the hip.
Most of these changes resolve with normal child growth and development,
provided protective,
preventive and/or therapeutic measures are taken.
The most appropriate treatment for early diagnosed DDH is Pavlik's harnesses,
which stabilize the hip and hold it in the normal and desired anatomical position,
allowing a correct development of immature structures and an adequate femur-acetabular fit.
When Pavlik’s harnesses do not work or when the diagnosis occurs later the indicated treatment is surgical hip reduction and casting.
In cases of severe or refractory DDH to the referred treatments,
there should be use of iliac and femoral osteotomies or acetabular reconstruction.
When untreated,
the possible complications (Fig. 1) of DDH are gait changes,
lower limb length discrepancies,
early degenerative joint disease and avascular necrosis.
Thus,
when diagnosed early,
DDH treatment is faster,
more successful and less invasive,
with a lower rate of late complications.
Ultrasound is the preferred method for diagnostic imaging of the immature hip and there are a number of techniques available for early detection of DDH.
Ultrasonographic criteria for DDH have been established for static imaging (which includes coronal and transverse planes of acetabular morphology) and for dynamic imaging of the flexed hip (with and without a modified Barlow stress maneuver).
By making possible the evaluation of the cartilaginous portions of the hip that may not have expression in radiography,
ultrasound allows an earlier diagnosis of DDH.
There are,
however,
two factors to be considered in the evaluation by ultrasonography:
- during the first month of life,
it may be normal to observe some acetabular immaturity and / or slight degrees of joint instability,
both non-pathological (Fig. 2).
98-99% resolve spontaneously.
Diagnostic examination should be performed only from 4-6 weeks of age.
- from 6 months of age,
with the progressive ossification of the femoral head,
ultrasound loses diagnostic value compared to radiography,
which becomes the preferred imaging modality for the diagnosis of DDH from this age.