Teardrop and sourcil line (TSL): a novel radiographic sign that predicts residual acetabular dysplasia (RAD) in DDH after closed reduction

Background: Residual acetabular dysplasia (RAD) is a major problem of developmental dysplasia of the hip (DDH) after dosed reduction (CR). Several parameters have been investigated as ways of predicting RAD; however, prediction of RAD remains controversial. The purpose of this study was to evaluate the radiographic sign of teardrop and sourcil line (TSL) in pediatric patients with DDH to enable prediction of RAD after CR. Methods: One hundred and twenty-five hips with DDH treated with CR and followed up for at least 2 years were included in this study. The mean age at CR was 18.3 months (range, 9 to 32 months) and the average follow-up time was 50.2 months (range, 24 to 89 months). The acetabular index (AI) was measured at different time points. The cases were divided into two groups according to whether TSL became continuous or not. The relationships among TSL, AI and RAD were analyzed. Results: The RAD incidence was 73.6% (92/125) at the last follow-up. AI at CR and TSL were the prognostic factors for RAD (P=0.017 and 0.001, respectively). Thirty-four hips showed a continuous TSL. There was a lower RAD rate in the TSL continuous group (P<0.001). There was no statistical difference in the AI at CR between the TSL continuous and discontinuous groups; however, the level of AI after CR was lower in the TSL continuous group. The TSL of 74% (20/27) hips became continuous after acetabular osteotomy surgery. Conclusions: The TSL continuous group had a lower AI and incidence of RAD than the discontinuous group. The TSL can be a predictive factor of RAD in DDH after CR and restore the continuous of TSL maybe a potential parameter that can help surgeons to make a judgment infra-operation.