Chapter 87: Developmental Dysplasia of the Hip

Patient Story

A three day old female was brought to her pediatrician for a routine newborn evaluation. Prenatally, the infant was noted by ultrasound to be in the frank breech position, and was born via Cesarean section at 40 weeks of gestation. She is the mother’s first child. At this visit, the pediatrician noted that the infant’s left thigh segment was shorter than the right, and a palpable “clunk” was felt when pressure was applied to lift the greater trochanter and the left hip was abducted (Figure 87-1). The pediatrician ordered an ultrasound of the left hip joint, which revealed a dislocated femoral head. The patient was subsequently placed in a Pavlik harness. After three months, the hip was completely reduced and stable on exam, and the harness was discontinued. Her standing x-ray of the hips at one year was normal.

Introduction

Developmental Dysplasia of the Hip (DDH) is a disorder of acetabular development leading to a shallow acetabulum (acetabular dysplasia), which may or may not be associated with an unstable or dislocated hip joint.¹

Synonyms

Hip dysplasia, Congenitally dislocated hip.

Epidemiology

• Most common in females, especially those of Native American descent.

• Incidence of DDH is approximately 1 in 100 live births, but only 1 in 1000 requires treatment.

• Can be discovered in neonates, infancy, or later in childhood.

Etiology and Pathophysiology

• Intrauterine positioning is crucial for proper development of the acetabulum.

• Intrauterine crowding can result in excessive hip flexion and adduction, which leads to acetabular flattening, stretching of the labrum, and ultimately hip joint instability.

• Frank breech positioning and oligohydramnios are the most common causes of intrauterine crowding.

Risk Factors

• Breech positioning (especially frank breech, 20 percent risk).

• Positive family history of DDH.

• First born.

• Female (6:1).

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