Developmental Dysplasia of the Hip

Screening Algorithm
Introduction
Absolute Risk of DDH per 1000 births
Additional Investigations
Areas of Uncertainty in Clinical Practice

Screening Algorithm

all newborn infants should have the Ortolani and Barlow tests performed by a trained examiner as part of the routine newborn examination

Unfortunately, infants who are unwell after delivery, and who require admission to neonatal intensive or special care units, often have this important part of their newborn examination omitted.
It must always be documented that the examination has been performed both in the infant's medical record and child health record.
infants, in whom the examiner is uncertain of the findings, should be re-examined by a more experienced clinician prior to discharge

Inexperienced examiners who are unsure whether what they are feeling is a 'click' or a 'clunk' are advised to enlist expert help.
infants in whom either test is positive should be assessed by an orthopaedic surgeon prior to discharge and fitted with a splint. Ultrasound can help confirm the clinical signs and assist in monitoring the response to treatment. There is no evidence to support the use of double or triple napkins until definitive treatment is instituted
high risk infants in whom examination is normal should have ultrasonography performed at about 6 -12 weeks after birth

High risk infants are those with
- breech presentation
- history of DDH in a first degree relative (parent or sibling)
- neuromuscular disease eg arthrogryposis, Spina Bifida
- low liquor volume

since DDH can develop over time, all infants (both high and low risk) with normal newborn examinations should have their hips regularly re-examined during the first year of life

Introduction

Developmental dysplasia of the hip (DDH) is the preferred term for the disease previously referred to as congenital dislocation of the hip since it recognises that presentation can follow a normal examination of the hips in the newborn period.

DDH refers to a spectrum of disorders of hip instability due either to the femoral head being able to move outside the acetabulum (luxation or dislocation), or abnormally within the acetabulum (subluxation or partial dislocation).
Early detection is vital since if DDH is left untreated the hip joint develops abnormally and surgical reduction is required. By contrast, early conservative management with splinting (eg Denis-Browne splint) allows the hip joint to develop normally and avoids the need for surgery in most cases.

Pathogenic factors for DDH include

abnormal rotation of the developing hip during the first trimester
neuromuscular disease, especially in the second trimester
abnormal mechanical forces e.g. oligohydramnios, breech presentation (particularly frank breech), in the third trimester
female infants (who are more susceptible to the maternal hormone relaxin)
postnatal mechanical forces associated with swaddling (African infants strapped to their mothers' backs with hips abducted have a very low incidence of DDH)

Absolute Risk of DDH per 1000 births

	Male	Female
Studies using Ortalani and Barlow tests for screening	4.1	19
First degree relative with history of DDH	6.4	32
Infant born after breech presentation	29.0	133

The relative risk for infants with a history of DDH in a first degree relative is 1.7 and when born after breech presentation (all types) is 7.0.

Screening

There is no 'gold standard' diagnostic test for DDH. The Ortolani and Barlow tests are widely used for screening.

The Ortolani test detects a dislocated hip reducing during the examination.
The Barlow test detects a hip dislocating or subluxing during the examination.

A positive Ortolani or Barlow test is one in which a distinctive 'clunk' is felt. 'Clicks' are often felt while performing these tests, are not predictive of DDH, but cause considerable confusion.

Readers who wish to learn the tests should

consult an authoritative text
be shown how to perform both tests by an expert
practice the tests on the 'Baby Hippy' manikin
practice the tests on many infants to perfect their technique

Additional Investigations

X-rays are unhelpful in assessment as the femoral head is cartilaginous until six months of age.

Areas of Uncertainty in Clinical Practice

Ultrasound examination of the hips has been advocated by some as the most effective method of screening for DDH. Although very sensitive as a screening tool, it has low specificity, is expensive and is operator dependent. For this reason, the American Academy of Pediatrics considers it an adjunct to clinical examination.

References

American Academy of Pediatrics. Clinical Practice guidelines: Early detection of developmental dysplasia of the hip. Pediatrics 2000; 105:896-905.

Griffin PP, Robertson WW Jr. Orthopedics. In: Avery GB, Fletcher MA, MacDonald MG, editors. Neonatology: Pathophysiology and management of the newborn. Philadelphia: Lippincott, Williams & Wilkins, 1999:1270.