Global Spinal Alignment Following Unilateral and Bilateral Periacetabular Osteotomy: A Standing Spine Radiographic...

Although periacetabular osteotomy (PAO) provides excellent clinical outcomes for patients with hip dysplasia, it still remains uncertain how it affects coronal and sagittal spinopelvic alignment. Therefore, this study aims to evaluate changes of coronal and sagittal spinopelvic parameters on standing AP and Lateral entire spine EOS radiographs following unilateral and bilateral PAO surgery.

Skeletally mature patients who underwent unilateral and bilateral PAO surgery for symptomatic hip dysplasia were included in this study. Standing anteroposterior (AP) and lateral EOS spine radiographs (EOS Imaging, Paris, France) obtained preoperatively and at the last follow-up were analyzed to assess changes in coronal and sagittal plane measurements. Preoperative and postoperative radiographic outcomes were assessed using the Paired Sample t test for normally distributed variables and the Wilcoxon Signed-Rank test for non-normally distributed variables.

A total of 31 patients with 44 hips were included in this study following our exclusion criteria. Of those, 18 patients (58%) underwent unilateral PAO (Unilateral group) and 13 patients (42%) underwent bilateral staged PAOs (Bilateral group). The mean age of patients at first surgery was 16±3 years in the Unilateral group and 19±5 years in the Bilateral group ( P >0.05). The mean preoperative Lateral Central Edge Angle (LCEA) was 13 degrees in the Unilateral group, which improved to 28 degrees at final follow-up ( P <0.001). In the Bilateral group, the mean LCEA was 16 degrees preoperatively, which improved to 32 degrees at last follow-up ( P <0.001). While the mean Acetabular Index (AI; Tönnis Angle) improved from 17 to 5 degrees at last follow-up in the Unilateral group ( P <0.001), it improved from 9 to -1 degrees at last follow-up in the Bilateral group ( P <0.001). There were no statistically significant preoperative and postoperative Pelvic Tilt, Sacral Slope, Pelvic Incidence, Lumbar Lordosis changes in the Unilateral and Bilateral groups.

Spinopelvic alignment did not significantly change following either unilateral or bilateral PAOs, as assessed on standing spine radiographs. Taken together with findings from previous research, our results suggest that pelvic tilt in skeletally mature patients with acetabular dysplasia is likely a fixed morphologic characteristic rather than a compensatory or reversible mechanism.

Level III.