Absence of False Acetabulum is a Potent Indicator for Predicting the Use of Subtrochanteric Osteotomy in Total Hip Arthroplasty for High Dislocated Hips

Abstract

Introduction: This study aimed to evaluate the predictive values of false acetabulum for assessment of whether to use subtrochanteric osteotomy.Materials and Methods: We retrospectively included a total of 182 patients (232 hips) affected by Crowe type IV developmental dysplasia who underwent primary THA with modular cementless stem from April 2008 to May 2019 in our institution. Based on radiographs and operative notes, we found 175 hips were performed with subtrochanteric osteotomy and 57 without subtrochanteric osteotomy, which was named (subtrochanteric osteotomy) STO group and non-STO group, respectively. The predictive values of absence of false acetabulum and distalization of greater trochanter were analyzed using receiver operating characteristic (ROC) curves.Results: ROC curves showed that absence of false acetabulum and distalization of greater trochanter had the AUCs of 0.957 and 0.987, respectively. And there was no statistical significance in the difference of these two AUCs (P=0.392). The optimal threshold for the distalization of greater trochanter was 4.83 cm, which resulted in a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 92.6%, 100%, 100%, and 81.4%, respectively. For the absence of false acetabulum, the sensitivity, specificity, PPV, and NPV were 94.9%, 96.5%, 98.8%, and 85.9%, respectively.Conclusions: The absence of false acetabulum may be a potent indicator in predicting the use of subtrochanteric osteotomy in high dislocated hips.