Isolated Hip Click and Developmental Dysplasia of the Hip

Background: There is variation in the literature regarding the relevance of an isolated hip click as a risk factor for developmental dysplasia of the hip (DDH). Rates of dysplasia in those referred for a hip click vary from 2.5-28%. Currently, the American Academy of Pediatrics guidelines do not encourage referral for a hip click with no other risk factors or abnormal findings. The purpose of this study is to evaluate the rate of DDH for patients prospectively referred for an isolated hip click.

Methods: This study included prospectively enrolled patients referred by their pediatrician to a single pediatric orthopedic center for concern for DDH between 2008-2014. We included patients referred for hip click felt by the pediatrician on exam and excluded patients with known risk factors for DDH (breech presentation or positive family history), known sonographic abnormalities and referrals for a “loose hip” or “unstable hip”. Ultrasounds were obtained upon initial presentation and sonographic dysplasia was defined as alpha angle <60 degrees and/or <50% femoral head coverage. Dislocated hips were diagnosed sonographically as ≤33% femoral head coverage. Radiographs were obtained at 1 year of age for hips with a normal initial ultrasound and acetabular indices (AI) were compared to normative data. Dysplasia at 1 year was diagnosed as AI >2SD above the mean.

Results: 344 children were referred for isolated hip click. Of these, 248 patients (72%) had a normal ultrasound while 96 patients (28%) had sonographic abnormality (mean age 6.9±6.2 weeks at initial ultrasound). For those with sonographic abnormality, 31 patients were treated with a Pavlik harness, 1 was treated with an abduction orthosis, and the remainder were observed. Severity of DDH varied with 65 (68%) patients demonstrating Graf IIa (physiologically immature) hips and 23 patients (6.7%) with an Ortolani-positive hip or fixed dislocation. Of those with a normal ultrasound at initial visit, 4/85 (4.7%) had a dysplastic hip with an acetabular index greater than 2 standard deviations above the mean at 1 year.

Conclusion: Our study suggests that children diagnosed by their pediatrician as having an isolated hip click may have higher rates of dysplasia than previously reported. These children mostly demonstrate mild sonographic dysplasia which resolved with observation. However, 6.7% presented with an Ortolani-positive hip or fixed dislocation. Even in the absence of other risk factors we encourage a screening ultrasound for children with a hip click.