Variable techniques in periacetabular osteotomy have been formulated for the treatment of acetabular dysplasia. However, few studies have compared the radiographic outcomes between different osteotomy types. This study compared modified triple innominate (MTI) osteotomy and Ganz osteotomy with respect to radiographic outcomes. Patients receiving MTI osteotomies and Ganz osteotomies at any time between 2006 and 2018 in a tertiary medical centre were recruited. Only patients with unilateral osteotomies were recruited to eliminate potential influence from the contralateral hip following periacetabular osteotomy. Patients having hip-joint dislocation, receiving simultaneous proximal femoral osteotomy, or having fewer than 2 years of follow-up were excluded. The radiographic parameters of preoperative and postoperative anteroposterior radiographs of the pelvis were measured, and Sharp’s angle (SA), the lateral centre-edge angle (CE angle), the femoral head extrusion index (FHEI), and the centre-head distance discrepancy (CHDD) were included for comparison. Among 55 participants, 23 received MTI osteotomies and 32 received Ganz osteotomies. The mean age at which patients underwent surgery was 21.9 years in the Ganz osteotomy group and 21.1 years in the MTI group. The mean follow-up length was 2.5 years. The preoperative radiographic parameters between groups differed only slightly and nonsignificantly. Both groups exhibited significantly improved SA, LCEA, and FHEI after surgery. The Ganz osteotomy group exhibited more favourable postoperative FHEI (13.5 vs. 24.3, p < 0.0001), CHDD (3.7 vs. 11.5, p < 0.0001), Sharp angle (45.0 vs. 41.8, p = 0.0489) and CE angles (28.3 vs. 21.1, p = 0.029) compared with the MTI osteotomy group. Notably, CHDD became better and worse following Ganz and MTI osteotomies, respectively; this suggests that the femoral head is pushed laterally in modified triple osteotomy. With respect to femoral head coverage and the medialization of the femoral head, Ganz osteotomy exhibits more favourable corrections in postoperative radiographic parameters than does MTI osteotomy.

Objective: Incorporating the sagittal stable vertebra (SSV) in posterior spinal fusion (PSF) may reduce postoperative distal junctional kyphosis (DJK) in adolescent idiopathic scoliosis (AIS), but its determination varies across reference methods and may be affected by patient posture. This study aims to investigate the SSV determined by different sagittal reference lines in predicting the risk of DJK after PSF in AIS patients. Methods: This retrospective cohort study evaluated AIS patients with Lenke Type 1 or 2 curves treated with PSF between January 2009 and July 2017. The inclusion or exclusion of SSV in PSF based on SSV determined by different reference lines was assessed for its association with the postoperative DJK. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and odds ratio were calculated. Results: One hundred twenty‐two patients (mean age at surgery: 15.1 ± 3.2 years) were included with the incidence of postoperative DJK 6.6%. PSF with the exclusion of SSV, defined by the vertebral level at which 50% of the vertebral body was anterior to the posterior sacral vertical line (PSVL), the midline between PSVL and the C7 plumb line (PSVL‐C7PL Midline), and the line connecting the center point of the C7 vertebral body and the posterior superior corner of the sacrum (C7PSL), was significantly associated with the occurrence of postoperative DJK. Among the evaluated reference lines, PSVL demonstrated numerically higher sensitivity, NPV, odds ratio, and area under the curve (AUC), although these differences in AUC did not reach statistical significance. Conclusions: Although there are concerns about whether standing posture affects the SSV determined by a specific reference line, this study demonstrates that PSVL might be an effective and convenient reference line for identifying SSV.