Learning Curve of Periacetabular Osteotomy for Acetabular Dysplasia in Adolescents and Adults

Abstract Background: The Bernese periacetabular osteotomy (PAO) has been the standard surgical treatment for adolescents and young adults with acetabular dysplasia. Despite its benefits, the procedure is technically demanding and associated with a steep learning curve. Objectives: This study aimed to characterize the learning curve of PAO and assess perioperative and radiographic outcomes across different phases of surgical proficiency. Materials and Methods: We conducted a retrospective review of 132 consecutive PAO cases performed between 2013 and 2021 at a single academic center. Patient demographics, operative time, blood loss, length of hospital stay, radiographic parameters, and complications were analyzed. Cumulative summation analysis and segmented regression were used to define learning curve phases. Results: Two inflection points were identified at cases 21 and 49, delineating the learning, proficiency, and competency phases. Operative time decreased significantly across phases (224.1–135.5 min, P < 0.001), along with intraoperative blood loss (811.9–554.8 mL, P = 0.007) and hospital stay (10.9–8.0 days, P < 0.001). Radiographic outcomes, including lateral center-edge angle, Tönnis angle, and anterior center-edge angle, improved significantly postoperatively. All revision surgeries ( n = 4) occurred during the learning phase. The upward rotation of the acetabular teardrop was proposed as a potential indicator of adequate mobilization of the acetabular fragment. Conclusions: Surgical proficiency in PAO was generally achieved after 21 cases, with continued refinement beyond 49 cases. The results suggest that operative efficiency and complication rates improve significantly with experience. These findings provide a framework for surgical training and program development in hip preservation surgery.