EP1.70 PAO, Arthroscopy, or Both? An Umbrella Review in Borderline Hip Dysplasia and the Arthroscopy Failure–to–PAO Pathway

Abstract Background Despite the success of periacetabular osteotomy (PAO) for hip dysplasia, management remains challenging due to frequent intra-articular pathology. The role of hip arthroscopy whether isolated, combined with PAO, or avoided remains controversial, with variable outcomes reported. In addition, failure of primary arthroscopy requiring subsequent PAO represents a clinically important yet underexplored treatment pathway. Purpose To perform an umbrella review as a next step beyond traditional reviews, comparing PAO, arthroscopy, and combined procedures in borderline dysplasia, focusing on failed arthroscopy progressing to PAO. Methods A systematic search of PubMed, Embase and Cochrane Library was performed to identify systematic reviews and meta-analyses on the surgical management of borderline hip dysplasia, forming the basis of this umbrella review. Studies were grouped into three domains: (1) PAO versus arthroscopy, (2) PAO versus PAO with arthroscopy, and (3) outcomes of PAO after failed arthroscopy. Data was extracted at the review level, including patient-reported outcomes (PROs), complications, reoperations, and conversion to total hip arthroplasty (THA). Methodological quality was assessed using AMSTAR-2 criteria. Results Eleven systematic reviews were included. Across systematic reviews comparing PAO and arthroscopy, both procedures showed improvement in patient-reported outcomes; however, high heterogeneity and differences in patient selection limited direct comparison. Improvement in modified Harris Hip Score ranged from approximately 20–29 points after PAO and 17.9–34.4 after arthroscopy, with no clear difference in short-term functional outcomes. Despite this, arthroscopy cohorts consistently demonstrated an approximately twofold higher risk of conversion to total hip arthroplasty compared to PAO. In systematic reviews comparing PAO with and without arthroscopy, both approaches resulted in meaningful improvement, with no consistent advantage of combined procedures. Importantly, the arthroscopy failure–to–PAO pathway emerged as a consistent finding across multiple systematic reviews. While PAO after failed arthroscopy led to clinical improvement, outcomes were generally inferior compared to primary PAO, suggesting that prior arthroscopy may negatively influence subsequent results. Conclusion Current evidence suggests that PAO, with or without arthroscopy, may be more reliable than arthroscopy alone in borderline hip dysplasia, given an approximately twofold higher risk of conversion to THA after arthroscopy. Although short-term outcomes may appear similar, failed arthroscopy requiring later PAO remains an important clinical concern, emphasizing careful patient selection. Level of Evidence Level IV, umbrella review of systematic reviews.