The Role of Ultrasonography in the Diagnosis of Developmental Dysplasia of the Hip

Abstract

Developmental dysplasia and dislocation of the hip (DDH) have great clinical interest with a reported case incidence in developed countries of 15 to 50 per 1000 live births. Early DDH treatment is effective, and early diagnosis is the key to treatment. Late diagnosis and delayed treatment lead to a significant increase in long-term morbidity. Early diagnosis need has motivated development of screening programs. Developmental dysplasia and dislocation of the hip is related to some known risk factors: female sex, breech and other abnormal positions at birth, positive family history, joint laxity, oligohydramnios, primiparity, cesarean section associated with difficulty presentations, intrauterine growth retardation, postural foot deformities, torticollis, high birth weight, older maternal age, postmaturity, and left greater than right hip involvement. Clinical screening programs of neonates for DDH have been used for the past 60 years including clinical tests (Ortolani, Barlow, and Galeazzi) that are very specific but with only approximately 60% sensitivity. Clinical tests have not as yet demonstrated acceptable reproducibility. To aid in early detection of DDH, ultrasonographic (US) methods were developed. Graf and Harcke noted advantages of US including lack of radiation, ability to visualize nonosseous structures, noninvasive, painless, repeatability, and multiplanar examination with prognostic parameters. Progressive sophistication of US allowed development of ability to do dynamic testing for instability with progressive monitoring of resolution of instability as a treatment adjunct that is more reliable than clinical evaluation alone.8Y10,40 Graf suggested that the overall cost of US screening is balanced by the cost of later need for more complex management of late diagnosis and treatment. Subsequent introduction of newer US methods confirmed its usefulness in avoiding late diagnosis of DDH (6 months to 4 years of age). In clinically unstable hips, US confirmed instability and femoral head displacement bilaterally when only unilateral involvement and instability had been clinically diagnosed. Ultrasonographic screening compared with clinical screening has been associated with the highest number of favorable outcomes of hip normalization without surgery. The United Kingdom Collaborative Hip Trial Group recently clearly showed that US screening in association with clinical evaluation allowed reduction in splinting rates without increased risks of adverse clinical, economic, or psychosocial outcomes. It is imperative to perform a clinical examination at each routine assessment of newborns. Clinical or sonographic methods alone are susceptible to some degree of failure, but in combination, failure rate of diagnosis is markedly diminished. Several authors advocated US as an effective screening method for DDH. When performed at birth, US detected nearly all abnormal hips and no hip that was considered normal at birth was later shown to be abnormal. Although US has been demonstrated to be a useful adjunct to DDH diagnosis, there is potential risk of misuse with false-positive and false-negative results which creates lack of concordance among physicians regarding timing of US use. Literature data are divided between those who propose universal US screening of all newborns and others who recommend selective US screening using clinical screening as a base.