The Ischial Spine in Developmental Hip Dysplasia: Unraveling theRole of Acetabular Retroversion in Periacetabular Osteotomy

Radiological diagnosis of acetabular retroversion (AR) is based on the presence of the crossover sign (COS), the posteriorwall sign (PWS), and the prominence of the ischial spine sign (PRISS). )e primary purpose of the study is to analyze the clinicalsignificance of the PRISS in a sample of dysplastic hips requiring periacetabular osteotomy (PAO) and evaluate retroversion insymptomatic hip dysplasia.Methods. In a previous paper, we reported the classic coxometric measurements of 178 patients withsymptomatic hip dysplasia undergoing PAO where retroversion was noted in 42% of the cases and was not found to be a majorfactor in the appearance of symptoms. In the current study, we have added the retroversion signs PRISS and PWS to our analysis.Among the retroverted dysplastic hips, we studied the association of the PRISS with the hips requiring PAO. We also defined theischial spine index (ISI) and studied its relationship to the coxometric measurements and AR.Results. In hips with AR, theoperated hips were significantly associated with the PRISS compared to the nonoperated ones (χ2�4.847). Additionally, the ISIwas able to classify acetabular version (anteverted, neutral, and retroverted acetabula). A direct correlation between the ISI and theretroversion index (RI) was found, and the highest degree of retroversion was found when the 3 signs of acetabular retroversionwere concomitantly present (RI�33.6%).Conclusion. )e PRISS, a radiographic sign reflecting AR, was found to be significantlyassociated with dysplastic hips requiring PAO where AR was previously not considered a factor in the manifestation of symptomsand subsequent requirement for surgery. Moreover, the PRISS can also serve as an adequate radiographic sign for estimatingacetabular version on pelvic radiographs.