FP14.3 Radiographic Characteristics and Patient-Reported Outcomes After Periacetabular Osteotomy in Hip and Spine Users with Acetabular Dysplasia

Abstract

Abstract ICLA14 - The Extra-Articular Masterclass: Endoscopic Repairs, Ischiofemoral Fixes, and Complex Alignment, Auditorium A (BMCC Level 1), October 9, 2026, 14:00 - 16:00 Background Spinal and pelvic pathologies can affect hip mechanics, with patients classified as “hip users” or “spine users” based on joint morphology and movement patterns. Understanding these differences may explain variations in the severity and presentation of acetabular dysplasia. This study aimed to determine the clinical characteristics of hip vs spine users, and compare patient-reported outcome measures (PROMs) after periacetabular osteotomy (PAO) between groups. Methods Between 2019 and 2023, 359 patients underwent PAO with or without hip arthroscopy for symptomatic acetabular dysplasia. Patients without minimum 2-year postoperative PROMs or preoperative lateral EOS radiographs were excluded, leaving 139 patients. Demographic, radiographic, and surgical data were analyzed. Patients were divided into hip users (n=32) and spine users (n=107) based on preoperative sacral slope (≤35° and >35°, respectively) as measured on lateral EOS radiographs. Results There were no differences in age, sex, body mass index (BMI), preoperative anterior and posterior wall index, Tönnis grade, or acetabular version between groups. The mean preoperative lateral center edge angle (LCEA) and anterior center edge angle (ACEA) were both higher in hip users than in spine users (LCEA: 20.5 ± 10.0 vs 15.8 ± 7.7, p=0.002; ACEA: 23.5 ± 10.1 vs 18.7 ± 10.4, p=0.02). Follow-up was similar for hip and spine users (3.3 ± 1.3 years vs 3.4 ± 1.3 years). There were no differences in preoperative or postoperative mHHS or iHOT-12 scores between groups (all p>0.05). Multivariable logistic regression demonstrated no differences in PASS achievement (mHHS: OR 0.75, 95% CI 0.23-2.45, p=0.64; iHOT-12: OR 0.81, 95% CI 0.27-2.44, p=0.70) or MCID achievement (mHHS: OR 1.14, 95% CI 0.39-3.34, p=0.81; iHOT-12: OR 0.93, 95% CI 0.29-2.99, p=0.90) after controlling for age, BMI, follow-up duration, prior ipsilateral surgery, preoperative PROMs, and bilateral PAOs. Conclusion This study found that most patients undergoing PAO for symptomatic acetabular dysplasia were classified as spine users. Radiographic parameters (LCEA and ACEA) suggest that spine users more often have severe dysplasia, whereas hip users more often exhibit borderline dysplasia. Despite these differences, both groups demonstrated comparable short- to mid-term outcomes following PAO, suggesting that spinopelvic classification does not affect early postoperative outcomes.