International Hip Dysplasia Institute (IHDI) is a radiographic classification system for initial evaluation of DDH, which takes as reference the hilgenreiner (H), Perkin lines (start from the triradiate cartilage and the outermost edge of the acetabulum, respectively), diagonal, and H point. Ramo[13 (link)] estimates an intraclass correlation interval (ICC) of 0.90 to 0.95 (Fig. 1a). Ogata “refined” CE Angle,[14 (link)] that evaluates bone condensation of the acetabular roof with a line that was drawn from the center of the metaphysis of the femoral neck, parallel to the longitudinal body axis and another line to the most lateral portion of said bone condensation (Fig. 1e), Ömeroğlu refers a reproducibility (κ= 0.54–0.76).[15 (link)] Buchholz–Ogden classification[16 ] to graduate AVN of the proximal femoral epiphysis AVN and includes type I: irregular ossification of the femoral head, II: lateral epiphyseal closure, valgus deformity of the head on the femoral neck, III: necrosis in the physis with growth alteration in the entire physis, IV: early closure of the medial physis with varus deformity, Roposch[17 (link)] refers a κ= 0.34 to 0.61. Acetabular index was estimated with initial acetabular index (IAI) and final acetabular index (FAI), by taking the H line as reference and a diagonal line up to the outer edge of the acetabular roof. They were measured twice, and the average was taken as the final measurement.
To quantify the main radiological results, the radiographic classification outcome system used “Ömeroğlu,”[18 (link)] which includes 3 measurements, the center edge angle of Wiberg, the acetabular angle of sharp, the center-trochanter distance (CTD), as well as 3 modifiers: the Ogata angle grade IV, the need for secondary treatment and the redislocation (Fig. 1 a–f). The score ranges fluctuated between 1 and 6 points and were considered satisfactory in hips with ≥ 5 points. Ömeroğlu[19 (link)] reported an inter and intraobserver reliability of 0.81 and 0.88, respectively.