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Screening for Developmental Hip Dysplasia

Role of Radiological Imaging
Screening Recommendations
High Risk Infants
Further Information
References

Developmental hip dysplasia is a relatively common disorder that, if not detected and treated in infancy, increases the likelihood of severe hip pain and precocious arthritis in young adulthood. Therefore, screening for developmental hip dysplasia by physical examination of the newborn and young infant is routine practice. Asymmetry in thigh and buttock folds, thigh length, or the degree of adduction and abduction are all key indicators of a single hip dislocation. The Ortolani and Barlow maneuvers are useful for detecting instability in infants up to about 3 months, since the head of the femur makes a palpable clunk if it is moved into and out of the acetabulum. High pitched clicks felt or heard during these maneuvers are usually due to the snapping of the iliotibial band over the greater trochanter and are not associated with dysplasia.
However, these tests are difficult to perform on a fussy, crying infant and none of these tests are pathognomonic. Consequently, there is a significant degree of fear of missing an early diagnosis and subsequent adverse developments.

Role of Radiological Imaging
Radiological imaging can be a valuable adjunct to the physical examination for hip dysplasia and as a means of monitoring treatment. However, even when infants are screened by both physical examination and ultrasound imaging, as many as1/5000 will have a hip dislocation diagnosed after 18 months of age.

Imaging is not helpful in the first few weeks of life when the hip joint is still developing. At this time, ultrasound imaging often reveals minor hip instability, most of which resolves without intervention.

MAP radiograph of the hips showing dislocated left hip in a 19-month-old female infant.
Plain film radiograph of the hips showing dislocated left hip in a 19-month-old female child.

Therefore, ultrasound imaging in the first month of life can lead to an increase in the number of infants who receive unnecessary treatment and additional imaging studies.

After 4 weeks of age, the hip has matured sufficiently for most minor hip instability to resolve. From this time until 4-6 months of age, ultrasonography is the modality of choice for evaluating infants for hip dysplasia because the femoral head and acetabulum are not yet calcified. After 4-6 months, ultrasonography is no longer useful and radiographic imaging is the modality of choice. When radiographic images of the hips are made, the genitals are routinely shielded from radiation exposure. Occasionally CT and MRI may be used as they are additional useful imaging tools for complex cases or preoperative evaluation.

Coronal ultrasound image of normal hip in a 4-week-old infant.
(A)
Coronal ultrasound image of the hip in a 4-week-old infant showing moderate hip dysplasia.
(B)
Coronal ultrasound image of hips of 4-week old infants.
(A) Normal Hip
(B) Hip showing moderate dysplasia.
F, Femoral head; Arrows point to the acetabulum

Screening Recommendations

High Risk Infants
The American Academy of Pediatrics recommends that all newborns with a positive Ortolani or Barlow sign be referred to an orthopedic surgeon, who will make treatment decisions based on a physical examination at this time. If the examination of the newborn is inconclusive, then it is recommended that the primary medical care provider perform a follow-up examination at 2 weeks. If this examination yields any positive or even inconclusive sign, or if positive signs develop at later well baby examinations it is recommended that the infant be referred to an orthopedist. If the dysplasia is diagnosed in the first few weeks, the orthopedist will recommend an ultrasound evaluation after 3-4 weeks of age for evaluation of the hip alignment as a baseline for assessment of the effectiveness of treatment.

Recommendations

Positive physical examination
(newborn or follow-up)

Refer to orthopedist
Inconclusive examination
(newborn)
Follow-up physical examination at 2 weeks
Inconclusive examination
(2 week follow-up)
Refer to orthopedist
Breech and girl Ultrasound imaging at 4-6 weeks and/or radiographic imaging at 6 mos.
Breech and boy or Family history and girl Consider ultrasound imaging at 4-6 weeks and/or radiographic imaging at 6 mos.
The risk of developmental hip dysplasia in girls born in breech presentation is as high as 12% because of the pressure on the joint from the mother’s spine in the later gestational period. For this reason, it is recommended that all such girls be imaged with ultrasound at about 4 weeks and/or radiographic imaging at 4-6 months of age even if the physical examination is negative. Imaging studies may be considered for boys born in breech presentation and for girls with a family history of developmental hip dysplasia.

Risk of Developmental Hip Dysplasia
Overall (European origin)* 0.1-0.2%
Female infant 1.9%
Positive family history, boy 0.94%
Positive family history, girl 4.4%
Breech presentation, boy 2.6%
Breech presentation, girl 12%
*Rare in those of African descent and more common in
those who practice swaddling or use cradle boards.


Further Information
For further questions on developmental hip dysplasia, please contact Katherine Nimkin, MD, Division of Pediatric Radiology (617-724-4207) or Brian Grottkau, MD, Chief of Pediatric Orthopedics (617-726-8523).

Imaging for pediatric hip dysplasia can be performed at the MGH Chelsea HealthCare Center and MassGeneral West Imaging in Waltham as well as at the MGH main campus.


References
French, LM and Dietz, FR. (1999) Screening for developmental dysplasia of the hip. Am Fam Physician 60: 177-84, 187-8

American Academy of Pediatrics. (2000) Clinical Practice Guideline: Early detection of developmental dysplasia of the hip. Pediatrics 105: 896-905



American College of Radiology (2000) ACR Appropriateness Criteria: Developmental dysplasia of the hip. Radiology 215S: 819-827