Background: Abduction bracing is often used to treat residual acetabular dysplasia in infants whose acetabular indices (AI) exceed 30 degrees after 6 months of age. However, little data exist to support this practice. The purpose of this study was to determine the efficacy of part-time abduction bracing in treating residual acetabular dysplasia by comparing a cohort of braced infants with a cohort of unbraced infants.
Methods: We performed a retrospective review of a consecutive series of patients with developmental dysplasia of the hip (DDH) treated at our institution over 4 years. Children with stable, treated DDH but residual acetabular dysplasia at 6 months of age were identified; those with available anteroposterior pelvic radiographs at 6 months and 1 year of age were included. Patients who required open surgical reduction and those with syndromic or neuromuscular diagnoses were excluded. On the basis of practice variations at our institution, some orthopaedists start bracing when the 6-month radiograph demonstrates an AI≥30 degrees, whereas others do not; we compared these 2 cohorts. Braced patients were instructed to wear an abduction orthosis during nights and naps until follow-up at 1 year of age. The AI at 6 months and 1 year of age for both cohorts were then measured by a single observer and the differences compared.
Results: Seventy-six hips in 52 patients were identified with residual dysplasia on the 6-month radiograph. Thirty-nine hips (27 patients) were unbraced, 31 hips (21 patients) were braced, and 6 hips (4 patients) were excluded for cross-over. Over a 6-month period, the braced cohort had significantly better improvement in the AI of 5.3 degrees (95% confidence interval, 4.3 to 6.3 degrees) compared to the unbraced cohort which had an improvement in the AI of only 1.1 degrees (95% confidence interval 0.6 to 1.6 degrees) (P<0.001).
Conclusions: In this comparative analysis of infants with residual acetabular dysplasia treated with abduction bracing or observation, part-time bracing significantly improved the acetabular index between 6 and 12 months of age. Part-time use of an abduction orthosis is effective for improving residual acetabular dysplasia in infants with DDH.
Level of Evidence: Level III—retrospective comparative study.