Hip Dysplasia in the Child and Adolescent

Key Points

Developmental dysplasia of the hip (DDH) represents a spectrum of abnormal hip mechanics and anatomy that can manifest during the newborn period, infancy, and later in life.
A high degree of clinical suspicion can allow for early diagnosis of acetabular dysplasia during the newborn period. Well-recognized risk factors for DDH include female sex, positive family history, and breech position during gestation.
Early treatment of acetabular dysplasia can be effective in preventing later sequelae, including hip osteoarthritis (OA).
Treatment of acetabular dysplasia in children after walking age and in adolescence requires surgical treatment.

Introduction

Hip dysplasia is one of the leading causes of hip OA and total hip replacement in young adults. Early recognition of hip dysplasia after birth allows for nonsurgical treatment with a high rate of success. The goals of surgical treatment are to obtain and maintain a concentric and stable hip reduction to allow for development and growth of the proximal femur and acetabulum. Current advancements in joint-preserving techniques have allowed for correction of even severe acetabular dysplasia in adolescents, with a low rate of complications.

Epidemiology

The true incidence of DDH is difficult to establish because of the wide spectrum of severity, ranging from acetabular dysplasia to subluxated and dislocated hips. The incidence varies widely among ethnic groups. The incidence of DDH in the modern era of clinical and sonographic screening is approximately 5.0 cases per 1000 live births. DDH is most likely multifactorial in nature. Although more than 60% of infants with DDH have no identifiable risk factor, both a first-degree relative with DDH and breech delivery have been considered high-risk factors. Hip positioning after birth in extension and adduction has been demonstrated to increase the risk of DDH.

Pathophysiology

Hip dysplasia represents a spectrum of pathophysiologic and anatomic abnormalities that, although initially treatable nonsurgically, tend to become more severe and less likely to resolve without surgical intervention over time. In the newborn with DDH, the posterosuperior acetabular rim may be abnormal, allowing the femoral head to subluxate or dislocate. If a newborn unstable hip becomes and remains persistently dislocated, secondary obstacles to reduction usually develop, including a fibrofatty pulvinar, hypertrophic ligamentum teres, a thickened transverse acetabular ligament, an inverted labrum (neolimbus), and an interposed iliopsoas tendon. Complete reduction of the hip can allow for acetabular remodeling with further growth. However, in the persistently dislocated hip, bony changes tend to develop and become permanent, including the characteristic flattening of the acetabular roof, thickening of the medial acetabular wall, and—in the case of frank dislocation—development of a false acetabulum.

Natural History

The natural history of the unstable hip in the newborn was reported by Barlow, who suggested that 60% of dislocatable hips resolved by 1 week and 88% by 2 months. However, Coleman reported resolution of only 5 of 23 unstable hips, illustrating a wide-ranging understanding of the natural history. The natural history of persistent acetabular dysplasia includes progressive premature degeneration of the hip joint with the onset of OA due to abnormal concentrations of mechanical hip joint forces on a decreased contact area. Wiberg defined abnormal femoral coverage as less than 25 degrees for the lateral center-edge angle (LCEA). Recent population-based studies have confirmed that acetabular dysplasia is a risk factor for hip OA. Cooperman and colleagues reported that all dysplastic hips with an LCEA less than 20 degrees developed OA by 22 years’ follow-up. However, the onset of OA was difficult to predict unless the hip was subluxated. Subluxation worsens the prognosis. Murphy and colleagues reported a study of the contralateral hip among 286 patients who were treated with total hip arthroplasty (THA) for OA due to acetabular dysplasia. They found that all hips with good function at 65 years of age were associated with a center edge angle greater than 16 degrees.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here