Purpose or Case Report: Several organizations have recommended ultrasound (US) screening for Developmental Dysplasia of the Hip (DDH) in infants with risk factors to facilitate early detection and treatment of the disease, and mitigate long-term morbidity. However, there is still debate on the value of screening US, particularly the dynamic stress component. The goal of our study was to evaluate the predictive value of selective screening hip US of infants with risk factors for detection of DDH requiring treatment, including the value of dynamic stress imaging.
Methods & Materials: We reviewed hip US studies performed at our institution for all infants with DDH risk factors between January 1, 2013 and June 30, 2014. Patients with positive physical findings of DDH were excluded. Alpha angle and femoral head coverage were measured on static coronal images. Hip stability was assessed with dynamic transverse imaging. Clinical data for patients referred to our institution’s orthopaedic clinic were collected from electronic medical records to September 30, 2016.
Results: Six hundred and twenty-nine patients (62% female) with risk factors for DDH and normal physical examination underwent selective hip US screening. More females than males had abnormal hip US (p<0.001). Although breech presentation was the most common indication for screening, family history of DDH was the risk factor most strongly associated with abnormal hip US (7/44, 16%). Of those with abnormal findings on hip US, 25/52 (48%) were not treated, including 21 patients with an alpha angle <60^o in one or both hips. Stability on dynamic stress imaging was documented in 561 of 629 patients (90%). Of the 587 patients with normal findings on static coronal imaging, 5 (<1%) were reported to have instability on dynamic stress imaging, of which 2/5 received treatment.
Conclusions: Our cohort shows an incidence of DDH similar to other reported cohorts. US is effective in screening for DDH in asymptomatic infants with risk factors for DDH. Dynamic instability occurs in <1% of asymptomatic infants with normal findings on static coronal imaging and is not a predictor of treatment. Therefore, dynamic stress imaging can be eliminated when screening asymptomatic infants with normal coronal static imaging.