DDH Follow-Up After 6 Months: Why Order X-Rays Later If Ultrasound Has Normalized?

Sunday, October 27, 2013: 10:55 AM
Blue Spring (Hyatt Regency Orlando, formerly the Peabody)
Eric Sarkissian, BS, John M. Flynn, MD, FAAP and Wudbhav N. Sankar, MD, Department of Orthopaedics, The Children's Hospital of Philadelphia, Philadelphia, PA

Purpose: Given concerns about costs and patient radiation exposure, we sought to evaluate the necessity of long-term radiographic follow-up of infants with developmental dysplasia of the hip (DDH) whose clinical exam and ultrasound returned to normal before 6 months of age. Our hypothesis was that infants with resolved hip instability and/or acetabular dysplasia on prior clinical and sonographic exams do not demonstrate residual acetabular dysplasia necessitating further radiographic monitoring.

Methods: We reviewed a consecutive series of infants with DDH presenting to our institution between January 2008 and January 2012. Infants less than 6 months of age with a previous DDH diagnosis were considered to have normalized DDH if their clinical exam and static/dynamic ultrasound revealed no signs of hip instability or acetabular dysplasia. We excluded infants with abnormal ultrasonographic indices and/or clinical exam, or those who required more invasive procedures to achieve hip stability at 6 months of age. Follow-up anteroposterior (AP) pelvic radiographs at approximately 6 months and 1 year of age were evaluated for evidence of residual acetabular dysplasia, defined as an abnormal acetabular index for age – greater than 30 degrees on the 6-month radiograph and greater than 28 degrees on the 12-month radiograph.

Results: Our study cohort consisted of 115 patients with normal sonographic and clinical exams before 6 months of age. At a mean age of 6.6 ± 0.8 months, 17% of all patients demonstrated signs of acetabular dysplasia on follow-up radiographs. Dysplasia was found in 13% of patients (10 of 79) with prior Pavlik harness treatment (PH) and 25% of patients (9 of 36) with risk factors for DDH (female gender, breech presentation, and/or positive family history) but no previous treatment with a Pavlik harness (RF). Patients who were not braced at this visit (n=106) were subsequently followed with an AP pelvic radiograph at an average age of 12.5 ± 1.2 months. The overall prevalence of acetabular dysplasia increased to 33%, including 34% of PH patients (25 of 74) and 31% of RF patients (10 of 32).

Conclusion: We were wrong. At 12 months of age, 33% of infants with previously normal clinical and sonographic examinations before 6 months of age had residual acetabular dysplasia. Longitudinal radiographic follow-up through at least 1 year of age is important to allow timely intervention and avoidance of future complications of residual dysplasia with increasing patient age.