Thank you very much for the opportunity to present. So as we know, FAI is increasingly recognized as a common cause of disabling hip pain, increasing the risk of injury to the labrum and the articular surface of the cartilage, as well as increasing the risk of early hip OA development. As such, hip arthroscopy has emerged as a popular treatment option for patients with symptomatic FAI, shown to produce successful outcomes of both mid- and long-term follow-up. However, a cohort of patients failed to achieve favorable outcomes following hip arthroscopy, and despite known anatomic variations in the hip, namely acetabular retroversion, which has been shown to increase the risk of labral injury, as well as early hip OA, it is not yet fully understood if patients with acetabular reversion achieve inferior outcomes when compared to patients with normal version or those with antiversion. And what we know is that most studies evaluating acetabular retroversion rely on plain radiographic findings characterized by the presence of a crossover sign, ischial spine sign, or posterior wall sign. However, what we also know is that these findings are subject to high inter- and intra-observer error, secondary to primarily morphologic variations in the hip and pelvis, as well as under exposure on radiographs and inconsistent patient positioning. As such, this has led to increased interest and focus on the use of CT and CT-based 3D bone modeling, allowing for a more objective and reproducible method of assessing acetabular orientation. And so the purpose of this study was to utilize a CT-based three-dimensional bone model in order to quantify acetabular reversion in patients with FAI undergoing primary hip arthroscopy and comparing these version measurements on these 3D bone models to two-dimensional CT version measurements in these current radiographic indices, and also analyzing the relationship between version and patient-reported outcome measures at a minimum of two-year follow-up. To do this, we obtained IRB approval to perform a retrospective review of a prospectively collected database evaluating patients undergoing primary hip arthroscopy for the treatment of FAI, while excluding patients undergoing revision surgery, those with degenerative changes or hip dysplasia, as well as those with any congenital hip disorders or a CT scan performed at an outside institution. All patients prior to surgery received a CT scan of the pelvis, after which a three-dimensional bone model was generated and aligned based on anatomic landmarks. We then measured the acetabular version at the 3 o'clock position based on the acetabular clock face and characterized hips as possessing either retroversion, normal version, or antiversion based on previously described parameters. What we also did is measured version on a two-dimensional CT axial slice, as well as looking and assessing for those radiographic indices we talked about for retroversion, the crossover, ischial spine, and posterior wall signs. Patient demographics, as well as patient-reported outcome measures, were then collected prior to surgery and at minimum two-year follow-up, followed by the performance of appropriate statistical analysis to evaluate the correlation between 3D bone model version measurements and those performed on two-dimensional axial CT slices, patient demographics, as well as the radiographic indices. And what we found was that of the 105 patients meeting inclusion criteria, 84 had a minimum of two-year follow-up, of which 70% were female with a mean age just under 34 years and a mean follow-up of 26 months. When looking at acetabular version at that 3 o'clock position, we found that a total of 14% of patients met criteria for acetabular retroversion, while 66% had normal version and 19% with acetabular antiversion. When looking at patient demographics based on version, we found no significant differences between version groups based on patient age, BMI, or sex. And then when looking at baseline imaging characteristics based on version, we found that there were significant in-group differences for version measurements performed on both CT 3D bone models, as well as our axial CT slice scans. And then when we looked at the percentage of patients that had acetabular retroversion, we found that a significantly higher portion of those patients possessed a posterior wall sign on plain radiographs, but not a crossover sign or ischial spine sign. And lastly, we did appreciate a positive correlation for version measurements performed on these 3D bone model scans, as well as our 2D axial CT slice measurement. When we looked at functional outcomes, we found that between version groups, there was no significant difference preoperatively. But at minimum two-year follow-up, patients with acetabular version did possess a lower modified Harris-Hipps score, IHART-12, as well as Vast Pain and Satisfaction score when compared to patients with normal version, as well as a lower Vast Satisfaction score when compared to patients with antiversion. Obviously, the study was not without limitations, owing primarily to its retrospective design. Furthermore, only the bony anatomy was analyzed, and no soft tissues were incorporated in our study. No patients underwent a PAO, and no postoperative imaging was obtained. Furthermore, the surgeries were performed by a single surgeon at a single institution, and only short-term follow-up was collected. And lastly, as we know, 3D CT bone modeling does not represent the current clinical standard of care. So in conclusion, what we found was that the plain radiographic indices of acetabular version are really not reliable in defining virtual retroversion when compared to measurements performed on 3D derived CT scans. However, the posterior wall sign was the only measure that was observed in a higher portion of patients with retroversion. However, there was a positive correlation between version measurements performed on 3D bone model scans, as well as our two-dimensional axial CT slice, and that patients with acetabular version did possess inferior outcomes when compared to patients with both normal version and those with antiversion. And so in conclusion, we really would argue that patients, when counseling, who have acetabular retroversion need to be aware of their expectations prior to and following surgery for the treatment of FAI utilizing primary hip arthroscopy. Thank you.

hip arthroscopy

FAI

femoroacetabular impingement

acetabular retroversion

CT-based 3D bone modeling