Ultrasound and radiographic outcomes of the Coxaflex brace in the treatment of developmental dysplasia of the hip (DDH): a multicentre prospective study

Abstract Purpose Early diagnosis is essential for the treatment of developmental dysplasia of the hip (DDH), and the use of abduction bracing is considered the gold standard for patients < 6 months of age. The aim of this study is to report an analysis of the results of using the Coxaflex abduction brace. Methods This multicentre prospective study included 44 hips in infants younger than 6 months with unilateral or bilateral reducible (Barlow-positive) developmental dysplasia of the hip, treated with the Coxaflex brace. DDH was diagnosed by clinical examination and ultrasound during outpatient screening. Serial ultrasound examinations were performed throughout treatment, while pelvic radiographs were obtained at the end of treatment to assess the acetabular index (AI) and the appearance of the proximal femoral ossification nucleus. Results The mean age at the start of treatment was 46 days (range, 4–150 days). The first follow-up (T1) was performed at 42 ± 13 days of treatment, a second follow-up (T2) at 91 ± 21 days, and a third follow-up (T3) at 134 ± 22 days. Ultrasound examinations were performed at each follow-up, which revealed a mean α angle of 47°±4° at the start of treatment. At the T1 follow-up, the mean α angle was 57°±7°, while on T2 and T3 they measured 63°±5° and 64°±5°, respectively. The angular increase on T1 and T2 was statistically significant ( p < 0.001). The X-ray examination was performed at an average of 162 ± 40 days and showed an AI of 23°±5° (range 14°-38°). Treatment was successful in all 44 hips. Three hips showed residual acetabular dysplasia at the time of ultrasonographic normalization and required prolonged brace treatment; all achieved radiographic normalization during follow-up. No patient required surgical treatment or conversion to another orthosis. Conclusions The Coxaflex brace appears to be an effective and well-tolerated treatment option for infants younger than 6 months with reducible (Barlow-positive) DDH. Since fixed or irreducible hip dislocations were not included in this study, these findings should not be generalized to those patients.