Developmental Dysplasia of the Hip

CHAPTER 18

Developmental Dysplasia of the Hip

Introduction/Etiology/Epidemiology

• Developmental dysplasia of the hip (DDH) encompasses a broad spectrum of hip disorders representing varying degrees of distortion in the relationship between the femoral head and acetabulum.

• These disorders range from radiologic diagnosis with normal examination findings to clinically dislocated hip.

• Most children are diagnosed as infants, but initial detection may occur at almost any age.

• Incidence of unstable hip is 1 to 1.5 per 1,000 live births; incidence is higher if defined by changes detected on ultrasonography and not gross dislocation.

• It may also be seen in association with neuromuscular disorders (eg, cerebral palsy, arthrogryposis, spina bifida).

• Etiology is multifactorial with mechanical and biologic causes

• Risk factors include breech positioning, ligamentous laxity, female sex, first born, family history, oligohydramnios, postnatal positioning (eg, hips held in adduction in papoose), and race (most common in white individuals and Native American groups).

Signs and Symptoms

• Symptoms depend on the age of the child.

— Infants and toddlers are typically asymptomatic. DDH may be associated with other intrauterine molding disorders, such as metatarsus adductus and torticollis.

— School-aged children may have some vague activity-related discomfort caused by leg-length discrepancy.

— Teenagers and young adults are usually asymptomatic but may have activity-related groin or buttock pain.

• Dislocated hip may demonstrate decreased abduction, with less than 60 degrees in infants being highly suspicious after 6 weeks of age.

Differential Diagnosis

• In infants or walking children, the leg shortening or hip instability may be related to congenital coxa vara, congenital short femur, or proximal femoral focal deficiency. Post-septic hip dislocation can also occur and result in limp and hip instability.

• In the older child, other etiologies of hip or knee pain should be considered, including slipped capital femoral epiphysis and Perthes disease.

Diagnostic Considerations

• Infants younger than 6 months

— In newborns, the proximal femoral epiphysis (upper femur) is not ossified, limiting the usefulness of plain radiographs.

— Ultrasonography

■Useful for assessing anatomy and following treatment in this age group

■Allows for a static and dynamic examination

■Screening before 6 weeks of age may be overly sensitive and result in overtreatment.

— Ortolani sign: Considered positive when a hip that is dislocated can be reduced and felt as a clunk. Occurs by bringing the involved hip into a flexed and abducted position (Figure 18-1, A).

— Barlow sign: Positive when a reduced hip can be dislocated by clunk associated with flexion and adduction of the hip (Figure 18-1, B).

— Galeazzi sign

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