Three-dimensional Acetabular Coverage Following Periacetabular Osteotomy: Comparison With Population-based Threshold Values Using Acetabular Sector Angles

Three-dimensional Acetabular Coverage Following Periacetabular Osteotomy: Comparison With Population-based Threshold Values Using Acetabular Sector Angles | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Three-dimensional Acetabular Coverage Following Periacetabular Osteotomy: Comparison With Population-based Threshold Values Using Acetabular Sector Angles Murat ONDER, Abdurrahman AYDIN, Sefa SELUK, Melisa DEMIR, Avni Ilhan BAYHAN This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8199721/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Periacetabular osteotomy (PAO) is a complex joint-preserving surgery for acetabular dysplasia. While traditionally focused on achieving superior femoral head coverage, the three-dimensional (3D) nature of acetabular morphology requires comprehensive assessment. Recently established population-based threshold values for acetabular sector angles (ASA) enable quantitative evaluation of dysplasia, but their relationship to post-PAO coverage remains unexplored. Methods This retrospective cross-sectional study included 33 patients (18 females, 15 males; mean age 23.4 years) who underwent unilateral PAO between January 2015 and December 2020. Preoperative and postoperative ASA measurements were obtained from standardized CT scans at four anatomical levels: superior, proximal, intermediate, and equatorial. Values were compared with contralateral normal hips and recently published dysplasia threshold values. Harris Hip Scores were recorded pre- and postoperatively. Results Harris Hip Scores improved significantly from 56 to 89 postoperatively (p < 0.001). Superior ASA increased from 108.5° to 129.0° (p < 0.001, Cohen's d = 1.92). Proximal posterior ASA increased by 21.8° (p < 0.001), and proximal anterior ASA by 11.9° (p = 0.025). Postoperative coverage approached contralateral hip values but remained below population-based thresholds for dysplasia at most levels. Notably, contralateral "normal" hips also fell below established thresholds. Conclusions PAO significantly improves 3D acetabular coverage, particularly in superior, posterolateral and superiolateral regions. However, both operated and contralateral hips demonstrate morphological features below population-based dysplasia thresholds, suggesting that surgical success criteria may differ from population norms. Radar chart visualization facilitates comprehensive assessment of acetabular morphology for surgical planning. hip dysplasia periacetabular osteotomy acetabular sector angle three-dimensional imaging computed tomography Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 INTRODUCTION Periacetabular osteotomy (PAO) remains the gold standard surgical treatment for preventing or delaying osteoarthritis in young adults with symptomatic acetabular dysplasia.[ 1 – 3 ] Traditionally, surgical planning and success have been evaluated using the lateral center-edge angle (CEA) of Wiberg measured on anteroposterior (AP) pelvic radiographs, with the goal of achieving adequate superior femoral head coverage.[ 4 , 5 ] However, the acetabulum is a three-dimensional (3D) structure, and relying solely on two-dimensional (2D) radiographic measurements may overlook critical anterior and posterior wall deficiencies.[ 6 , 7 ] The sourcil, representing the weight-bearing dome of the acetabulum on radiographs, provides limited information about circumferential coverage. Furthermore, acetabular version can significantly influence the apparent superior coverage on AP radiographs, potentially leading to inaccurate assessment of true femoral head coverage.[ 7 ] Recent studies have demonstrated that developmental hip dysplasia is not limited to deficient superior coverage but affects all acetabular walls.[ 8 ] The Ottawa classification categorizes acetabular dysplasia into anterior, posterior, and global patterns, each associated with distinct clinical symptoms and pathomechanics.[ 9 – 11 ] Insufficient anterior coverage may cause pain during hip extension, while posterior deficiency can present with symptoms mimicking piriformis syndrome or sciatica. Additionally, excessive anterior coverage may lead to femoroacetabular impingement and labral tears, while posterior insufficiency predisposes to instability and pain. Ultimately, all these patterns contribute to accelerated cartilage degeneration and osteoarthritis development.[ 9 – 11 ] To address these limitations, the concept of acetabular sector angles (ASA) has been developed, enabling quantitative 3D assessment of acetabular morphology using computed tomography (CT).[ 12 – 14 ] Most importantly, Verhaegen and colleagues recently established population-based threshold values for ASA measurements, providing objective criteria for distinguishing dysplastic from normal acetabular morphology.[ 14 ] Despite the widespread use of PAO and the recent establishment of dysplasia threshold values, no studies have examined how postoperative acetabular coverage relates to these population-based norms. Understanding this relationship is crucial for optimizing surgical correction targets and potentially refining surgical techniques. The purpose of this study was to: (1) evaluate changes in 3D acetabular coverage following PAO using ASA measurements at multiple anatomical levels, (2) compare postoperative coverage with contralateral asymptomatic hips, and (3) assess how both operated and contralateral hips relate to recently established dysplasia threshold values. We hypothesized that PAO would significantly improve acetabular coverage across all regions but that postoperative values might still differ from population-based normal thresholds. Additionally, we utilized radar charts for intuitive visualization of 3D acetabular morphology changes. MATERIALS AND METHODS Study Design and Patient Selection This retrospective cross-sectional study was conducted at a single tertiary referral center. The study was approved by the Institutional Review Board (approval number [328] , approval date [10.2025] ), and the requirement for written informed consent was waived due to the retrospective nature of the study. All procedures were performed in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments. We reviewed medical records of all patients who underwent PAO for symptomatic acetabular dysplasia between January 2015 and December 2020. A total of 84 patients were initially identified. Patients were included if they: (1) underwent unilateral PAO for symptomatic acetabular dysplasia, (2) had CEA 25°) on radiographs, (5) had spherical femoral head morphology, and (6) had minimum 24-month follow-up. Exclusion criteria were: (1) bilateral hip dysplasia (CEA < 20° bilaterally) (n = 13), (2) previous hip surgery in childhood (n = 7), (3) Perthes disease or other causes of aspherical femoral head (n = 2), (4) inadequate preoperative or postoperative CT imaging (n = 12), (5) incomplete follow-up data (n = 27). Following application of these criteria, 33 patients were included in the final analysis (Fig. 1 ). The final cohort consisted of 18 females and 15 males with a mean age of 23.4 years (range, 16–31 years) at the time of surgery. Mean follow-up duration was 62 ± 16.4 months (range, 24–96 months) (Table 1 ). Table 1 Patient Demographics and Clinical Outcomes Characteristic Value Number of patients 33 Gender Male 15 (45.5%) Female 18 (54.5%) Age at surgery (years) 23.4 ± 4.2 (16–31) Follow-up duration (months) 62 ± 16.4 (24–96) Harris Hip Score Preoperative 56 ± 8.3 (38–72) Postoperative 89 ± 5.7 (78–98) Change + 33 ± 9.1 P-value < 0.001 Data presented as mean ± SD (range) or n (%) Surgical Technique All PAO procedures were performed by the senior author using the Bernese periacetabular osteotomy technique as described by Ganz et al.[ 5 ] The surgery involves four osteotomy cuts: (1) supra-acetabular, (2) infra-acetabular (ischial), (3) posterior column, and (4) anterior column (pubic), allowing reorientation of the acetabular fragment to improve femoral head coverage. The acetabular fragment was mobilized and repositioned to achieve a target postoperative CEA of 30–35°, ensuring femoral head coverage without causing femoroacetabular impingement. Fixation was achieved using 3–4 cortical screws. All patients followed a standardized rehabilitation protocol including protected weight-bearing for 8 weeks postoperatively. CT Imaging Protocol and Standardization All patients underwent pelvic CT scanning using standardized protocols (120 kVp, automatic mA modulation, 1-mm slice thickness, 0.5-mm increment) on 64-slice or 128-slice multidetector CT scanners (GE Healthcare or Siemens Healthineers). Images were obtained with patients in supine position with feet internally rotated 15°. Preoperative CT scans were performed within 2 weeks before surgery, and postoperative CT scans were obtained at minimum 6 months following surgery (mean 8.3 months, range 6–12 months) to allow for bone healing and remodeling. Acetabular Sector Angle Measurements All measurements were performed using a dedicated PACS workstation (Extreme PACS, RADinfo Systems Inc.) with multiplanar reformation (MPR) capabilities by two experienced observers: a fellowship-trained musculoskeletal radiologist with 10 years of experience and an experienced hip preservation surgeon. To eliminate measurement errors from pelvic tilt, standardized axial planes were established using MPR following the methodology described by Verhaegen et al.[ 14 ] The axial plane was adjusted to pass through both femoral head centers, ensuring consistent measurement planes across all patients. ASA measurements were obtained at four standardized levels as described by Verhaegen et al.:[ 14 ] (Fig. 2 ) Equatorial Level : Axial slice through the true femoral head center (largest femoral head diameter) Intermediate Level : Midway between equatorial and proximal levels Proximal Level : Most superior axial slice through the femoral head center Superior Level : Measured on coronal reformatted images For each axial level, anterior ASA (AASA) and posterior ASA (PASA) were measured. ASA was defined as the angle between: (1) a line connecting both femoral head centers, and (2) a line from the ipsilateral femoral head center to the anterior or posterior acetabular rim. Superior ASA (sup. ASA) was measured on coronal images as the angle between the line connecting femoral head centers and the line to the superolateral acetabular rim. The following nine angles were recorded for each hip: Superior ASA (sup. ASA) Proximal anterior ASA (prox. AASA) Proximal posterior ASA (prox. PASA) Intermediate anterior ASA (inter. AASA) Intermediate posterior ASA (inter. PASA) Equatorial anterior ASA (equat. AASA) Equatorial posterior ASA (equat. PASA) Additionally, the lateral center-edge angle (CEA) was measured on AP pelvic radiographs according to the method described by Wiberg.[ 15 ] All measurements were performed for: (1) dysplastic hips preoperatively, (2) operated hips postoperatively, and (3) contralateral asymptomatic hips. The contralateral hip measurements served as an internal control, representing the patient's baseline acetabular morphology. Clinical Outcome Assessment Clinical Outcome Assessment Harris Hip Scores (HHS) were recorded preoperatively and at final follow-up by an independent assessor blinded to the imaging measurements. The HHS ranges from 0 to 100, with higher scores indicating better hip function. Reliability Assessment To assess measurement reliability, the primary observer (musculoskeletal radiologist) repeated all measurements after a 10-day washout period, blinded to initial values. The secondary observer (hip preservation surgeon) independently performed measurements on identical images. Intraclass correlation coefficients (ICCs) with 95% confidence intervals were calculated for all measurements. ICC values were interpreted as follows: poor (< 0.40), fair (0.40–0.59), good (0.60–0.74), or excellent (≥ 0.75). Statistical Analysis Statistical analyses were performed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA). Normality of continuous variables was assessed using the Shapiro-Wilk test. Descriptive statistics included means, standard deviations, and ranges for continuous variables, and frequencies and percentages for categorical variables. Paired comparisons between preoperative and postoperative measurements in the operated hip were performed using paired t-tests for normally distributed variables or Wilcoxon signed-rank tests for non-normally distributed variables. Similarly, paired comparisons between postoperative operated hips and contralateral asymptomatic hips were performed using the same approach. Effect sizes were calculated using Cohen's d, interpreted as small (0.2–0.49), medium (0.5–0.79), or large (≥ 0.8). Given the exploratory nature of some comparisons, no correction for multiple comparisons was applied, but we note this as a limitation. For comparison with Verhaegen et al.'s threshold values,[ 14 ] we calculated the proportion of hips (preoperative, postoperative, and contralateral) that met or exceeded each threshold value for dysplasia. All statistical tests were two-tailed, and statistical significance was set at p < 0.05. ICC values were calculated using a two-way random effects model for absolute agreement. RESULTS Clinical Outcomes Harris Hip Scores improved significantly from a mean of 56 preoperatively (range, 38–72) to 89 postoperatively (range, 78–98) (p < 0.001, 95% CI: 28.5–37.5), representing a mean improvement of 33 points. All patients reported satisfaction with the surgical outcome at final follow-up, and no patient required conversion to total hip arthroplasty during the follow-up period. Radiographic Outcomes The lateral center-edge angle of Wiberg increased significantly from a mean of 13.3 ± 8.35° preoperatively to 38.9 ± 9.33° postoperatively (p < 0.001, 95% CI: 22.1–29.1, Cohen's d = 2.91), representing excellent correction of superior coverage. Three-Dimensional Acetabular Coverage Changes Preoperative Versus Postoperative Comparisons (Table 2 ) Table 2 Comparison of Acetabular Sector Angle Values Before and After Periacetabular Osteotomy Parameter Preoperative (Mean ± SD) Postoperative (Mean ± SD) Change (Δ) P-value 95% CI Cohen's d Wiberg CEA (°) 13.3 ± 8.35 38.9 ± 9.33 + 25.6 < 0.001 22.1–29.1 2.91 Sup. ASA (°) 108.5 ± 13.04 129.0 ± 7.55 + 20.5 < 0.001 14.8–26.2 1.92 Prox. AASA (°) 66.9 ± 22.97 78.8 ± 29.25 + 11.9 0.025 1.6–22.2 0.44 Prox. PASA (°) 92.8 ± 14.96 114.6 ± 15.22 + 21.8 < 0.001 14.2–29.4 1.46 Inter. AASA (°) 48.3 ± 13.76 57.2 ± 25.22 + 8.9 0.086 -1.3-19.1 0.42 Inter. PASA (°) 89.4 ± 12.42 100.7 ± 17.97 + 11.3 0.003 4.2–18.4 0.72 Equat. AASA (°) 39.9 ± 9.71 43.8 ± 15.41 + 3.9 0.268 -3.1-10.9 0.29 Equat. PASA (°) 84.2 ± 12.41 92.8 ± 14.18 + 8.6 0.010 2.3–14.9 0.65 CEA = center-edge angle; ASA = acetabular sector angle; Sup. = superior; Prox. = proximal; Inter. = intermediate; Equat. = equatorial; AASA = anterior acetabular sector angle; PASA = posterior acetabular sector angle; SD = standard deviation; CI = confidence interval. Statistical comparisons performed using paired t-tests for normally distributed variables or Wilcoxon signed-rank tests for non-normally distributed variables. Superior ASA demonstrated the largest increase, from 108.5 ± 13.04° preoperatively to 129.0 ± 7.55° postoperatively, representing a mean increase of 20.5° (p < 0.001, 95% CI: 14.8–26.2, Cohen's d = 1.92). This finding confirms that PAO primarily enhances superolateral coverage, which correlates with the improvement in radiographic CEA. At the proximal level, both anterior and posterior coverage improved significantly. Proximal PASA increased from 92.8 ± 14.96° to 114.6 ± 15.22°, a mean increase of 21.8° (p < 0.001, 95% CI: 14.2–29.4, Cohen's d = 1.46). Proximal AASA increased from 66.9 ± 22.97° to 78.8 ± 29.25°, a mean increase of 11.9° (p = 0.025, 95% CI: 1.6–22.2, Cohen's d = 0.44). At the intermediate level, posterior coverage showed significant improvement with inter. PASA increasing from 89.4 ± 12.42° to 100.7 ± 17.97°, a mean increase of 11.3° (p = 0.003, 95% CI: 4.2–18.4, Cohen's d = 0.72). However, intermediate anterior coverage (inter. AASA) demonstrated a trend toward improvement that did not reach statistical significance (48.3 ± 13.76° to 57.2 ± 25.22°, mean increase 8.9°, p = 0.086, 95% CI: -1.3 to 19.1, Cohen's d = 0.42). At the equatorial level, equatorial PASA increased from 84.2 ± 12.41° to 92.8 ± 14.18° (p = 0.010, 95% CI: 2.3–14.9, Cohen's d = 0.65), while equatorial AASA showed a non-significant trend toward improvement (39.9 ± 9.71° to 43.8 ± 15.41°, p = 0.268, 95% CI: -3.1 to 10.9, Cohen's d = 0.29). Postoperative Versus Contralateral Normal Hip Comparisons (Table 3 ) Table 3 Comparison of Postoperative Acetabular Coverage with Contralateral Normal Hip and Verhaegen Threshold Values Parameter Postoperative Operated Hip (Mean ± SD) Contralateral Normal Hip (Mean ± SD) P 95% CI Verhaegen Threshold for Dysplasia Operated Hip vs Threshold (Δ) Contralateral Hip vs Threshold (Δ) Wiberg CEA (°) 38.9 ± 9.33 29.4 ± 5.80 0.006 3.1–15.9 25° + 13.9° + 4.4° Sup. ASA (°) 129.0 ± 7.55 118.0 ± 13.71 < 0.001 5.8–16.2 116° + 13.0° + 2.0° Prox. AASA (°) 78.8 ± 29.25 89.5 ± 25.89 0.213 -6.1-27.5 133° -54.2° -43.5° Prox. PASA (°) 114.6 ± 15.22 110.6 ± 18.31 0.462 -6.9-14.9 137° -22.4° -26.4° Inter. AASA (°) 57.2 ± 25.22 60.3 ± 15.70 0.535 -6.7-12.9 72° -14.8° -11.7° Inter. PASA (°) 100.7 ± 17.97 97.3 ± 13.56 0.598 -9.2-15.9 107° -6.3° -9.7° Equat. AASA (°) 43.8 ± 15.41 50.1 ± 12.73 0.041 0.3–12.3 57° -13.2° -6.9° Equat. PASA (°) 92.8 ± 14.18 95.2 ± 9.19 0.554 -5.6-10.4 97° -4.2° -1.8° CEA = center-edge angle; ASA = acetabular sector angle; Sup. = superior; Prox. = proximal; Inter. = intermediate; Equat. = equatorial; AASA = anterior acetabular sector angle; PASA = posterior acetabular sector angle; SD = standard deviation; CI = confidence interval. Statistical comparisons between postoperative operated hip and contralateral normal hip performed using paired t-tests or Wilcoxon signed-rank tests as appropriate. Verhaegen threshold values represent the minimum values distinguishing normal from dysplastic hips as established by Verhaegen et al. (2023).[ 14 ] Negative delta values indicate coverage below the dysplasia threshold. When comparing postoperative operated hips to contralateral asymptomatic hips, interesting patterns emerged. The superior ASA was significantly greater in operated hips (129.0 ± 7.55° vs. 118.0 ± 13.71°, p < 0.001, 95% CI: 5.8–16.2), indicating that surgical correction resulted in superior coverage exceeding the contralateral hip. However, at other anatomical levels, no significant differences were observed between postoperative operated hips and contralateral asymptomatic hips: Prox. AASA: 78.8 ± 29.25° vs. 89.5 ± 25.89°, p = 0.213 Prox. PASA: 114.6 ± 15.22° vs. 110.6 ± 18.31°, p = 0.462 Inter. AASA: 57.2 ± 25.22° vs. 60.3 ± 15.70°, p = 0.535 Inter. PASA: 100.7 ± 17.97° vs. 97.3 ± 13.56°, p = 0.598 Equat. PASA: 92.8 ± 14.18° vs. 95.2 ± 9.19°, p = 0.554 The only significant difference besides superior coverage was at the equatorial anterior level, where contralateral hips demonstrated greater coverage (43.8 ± 15.41° vs. 50.1 ± 12.73°, p = 0.041, 95% CI: 0.3–12.3). Comparison with Population-Based Threshold Values (Table 3 ) When comparing both postoperative operated hips and contralateral asymptomatic hips to the dysplasia threshold values established by Verhaegen et al.,[ 14 ] a striking finding emerged: both groups fell substantially below the threshold values at most anatomical levels. For postoperative operated hips: Sup. ASA: 129.0° vs. threshold 116° (exceeded threshold) Prox. AASA: 78.8° vs. threshold 133° (54° below threshold) Prox. PASA: 114.6° vs. threshold 137° (22.4° below threshold) Inter. AASA: 57.2° vs. threshold 72° (14.8° below threshold) Inter. PASA: 100.7° vs. threshold 107° (6.3° below threshold) Equat. AASA: 43.8° vs. threshold 57° (13.2° below threshold) Equat. PASA: 92.8° vs. threshold 97° (4.2° below threshold) Similar patterns were observed for contralateral asymptomatic hips, which also consistently fell below threshold values at most levels except superior coverage. Radar Chart Visualization (Figs. 3 – 7 ) Radar charts provided intuitive visualization of the 3D acetabular coverage patterns (Figs. 3 – 7 ). These charts clearly demonstrated: Global improvement in acetabular coverage following PAO (Fig. 3 ) Near-symmetry between postoperative operated hips and contralateral asymptomatic hips (Fig. 4 ) Persistent deficiency relative to population-based thresholds in both postoperative operated and contralateral asymptomatic hips (Figs. 5 – 6 ) Overlaid comparison showing all groups simultaneously (Fig. 7 ) Reliability Analysis Intraobserver ICC values ranged from 0.82 to 0.94, and interobserver ICC values ranged from 0.78 to 0.91 demonstrating high reliability of the measurement technique. DISCUSSION This study demonstrates that PAO significantly improves three-dimensional acetabular coverage, particularly in the superior, posterolateral and superiolateral regions, with corresponding improvements in clinical outcomes. However, we identified an unexpected finding: both postoperative operated hips and contralateral "normal" hips demonstrated acetabular morphology that fell below recently established population-based threshold values for dysplasia at most anatomical levels. This raises important questions about the relationship between acetabular morphology, clinical symptoms, and surgical success criteria. Three-Dimensional Assessment of Acetabular Dysplasia Traditional two-dimensional radiographic assessment of hip dysplasia, while convenient and widely available, provides limited information about the true three-dimensional nature of acetabular deficiency.[ 6 , 7 ] Our findings support previous work demonstrating that dysplasia affects not only the superior dome but also the anterior and posterior walls.[ 8 ] The Ottawa classification has highlighted the clinical relevance of these regional differences, with anterior deficiency causing extension-related pain and posterior deficiency presenting with symptoms that may be misattributed to lumbosacral pathology.[ 9 – 11 ] The use of acetabular sector angles measured on CT scans enables comprehensive quantitative assessment of acetabular morphology at multiple anatomical levels.[ 12 – 14 ] In our cohort, preoperative dysplastic hips demonstrated deficiencies across all measured regions, not limited to superior coverage. This underscores the importance of considering the entire acetabular perimeter when planning and executing corrective surgery. Efficacy of Periacetabular Osteotomy Our results demonstrate that PAO effectively improves acetabular coverage across multiple regions, with the most substantial improvements occurring in superior and posterior coverage at the proximal level. The mean increase of 20.5° in superior ASA and 21.8° in proximal posterior ASA represents clinically meaningful improvement, consistent with the surgical goal of reorienting the acetabulum to better contain the femoral head. These findings align with previous studies demonstrating that PAO enhances superolateral and anterolateral femoral head coverage.[ 16 – 20 ] The improvement in Harris Hip Scores from 56 to 89 confirms that these morphological improvements translate into meaningful clinical benefit, consistent with excellent long-term outcomes reported in other PAO series.[ 29 – 31 ] Interestingly, while anterior coverage improved at the proximal level, the improvements at intermediate and equatorial levels were more modest and inconsistent. This may reflect technical limitations of the PAO technique or surgical philosophy prioritizing superior and posterior correction. Future studies should explore whether more aggressive anterior correction at lower levels would provide additional clinical benefit or potentially cause anterior femoroacetabular impingement. The "Normal" Contralateral Hip Paradox One of the most striking findings of this study is that contralateral asymptomatic hips, which served as internal controls and met traditional radiographic criteria for normal morphology (CEA > 25°), nevertheless demonstrated acetabular sector angles substantially below the dysplasia thresholds established by Verhaegen et al.[ 14 ] in a large population-based study. Several explanations for this discrepancy warrant consideration: First, patients with symptomatic unilateral dysplasia may have a genetic or developmental predisposition affecting both hips, even when only one hip becomes clinically symptomatic. Studies have shown that 30–40% of patients with unilateral symptomatic dysplasia eventually develop symptoms in the contralateral hip.[ 22 – 25 ] Our finding suggests that many contralateral "normal" hips may represent borderline or mild dysplasia that has not yet become symptomatic due to better compensatory mechanisms, lower activity levels, or shorter duration of loading. Second, there may be population-specific variations in normal acetabular morphology. Verhaegen et al.'s thresholds were derived from a North American population,[ 14 ] while our study was conducted in Turkey. Anthropometric differences between populations could influence normal acetabular architecture, although previous studies have not consistently demonstrated substantial ethnic variations in acetabular morphology. Third, the presence of asymptomatic morphological abnormalities is well-recognized in hip pathology. Similarly, acetabular morphology falling below theoretical dysplasia thresholds may not necessarily become symptomatic, depending on activity demands, neuromuscular function, and cartilage quality. Implications for Surgical Planning and Success Criteria Our findings suggest that the goal of PAO may not be to achieve acetabular morphology meeting population-based dysplasia thresholds, but rather to improve coverage to levels approaching the patient's contralateral hip while ensuring adequate superior dome coverage to prevent progression to osteoarthritis. This patient-specific approach recognizes that individual baseline morphology may differ from population norms. The excellent clinical outcomes achieved in our cohort, despite postoperative ASA values remaining below Verhaegen's thresholds at most levels, supports this concept. Patients improved dramatically from a mean Harris Hip Score of 56 (poor) to 89 (excellent), with postoperative coverage similar to their contralateral asymptomatic hips. This suggests that matching or slightly exceeding the contralateral hip morphology may represent an appropriate surgical target for PAO, rather than striving to achieve population-based threshold values. However, this interpretation requires cautious validation. Long-term follow-up studies are needed to determine whether patients whose postoperative coverage remains below population thresholds experience different long-term outcomes compared to those meeting these thresholds. Additionally, the finding that contralateral hips are below thresholds suggests these patients may benefit from preventive interventions or close monitoring, even in the absence of current symptoms. Utility of Radar Chart Visualization The radar charts used in this study provide an intuitive method for visualizing the complex three-dimensional nature of acetabular coverage. Unlike tables of numerical data, radar charts enable immediate visual appreciation of coverage patterns, regional deficiencies, and the global nature of coverage changes following surgery. This visualization tool may prove valuable for surgical planning, patient education, and comparative research. Tamura et al. previously demonstrated that dysplastic hips exhibit cartilage degeneration primarily in lateral and anterosuperior regions, with persistent labral damage in areas of anterior under-coverage.[ 17 ] Igei et al. used similar radar charts to demonstrate comprehensive improvement in acetabular coverage following curved PAO.[ 18 ] Our study extends this work by comparing postoperative coverage not only with preoperative and contralateral values but also with population-based threshold values, providing a more complete picture of acetabular morphology optimization. Comparison with Previous Literature Igei et al. evaluated 3D femoral head coverage before and after curved PAO using radar charts, demonstrating improvement in coverage across all regions.[ 18 ] However, their study used contralateral asymptomatic hips as the normal comparison group, without considering that these hips might themselves represent borderline dysplasia. Our study advances this understanding by incorporating population-based threshold values as an additional reference point. Verhaegen et al.'s landmark study established ASA threshold values by comparing 251 asymptomatic hips with 72 dysplastic hips requiring PAO, using receiver operating characteristic analysis to determine optimal cutoff values distinguishing these groups.[ 14 ] Notably, our study is the first to compare postoperative PAO coverage with these threshold values, revealing the important finding that even successful surgical correction may not achieve coverage meeting these thresholds. Recent studies have emphasized the importance of three-dimensional surgical planning and intraoperative navigation for optimizing PAO correction.[ 19 , 20 ] Schwarz et al. described a navigation method using external fixation that enables real-time assessment of three-dimensional acetabular reorientation.[ 19 ] Our findings support the value of three-dimensional assessment but suggest that surgical targets should be individualized rather than aiming for a single set of population-based threshold values. Limitations Several limitations warrant acknowledgment. First, the retrospective single-center design and relatively modest sample size limit generalizability. Although our sample size provided adequate statistical power for detecting the observed differences, a larger multicenter cohort would strengthen confidence in these findings and enable subgroup analyses by age, gender, or dysplasia severity. Second, the study did not correlate specific ASA measurements with functional outcomes or patient-reported outcome measures beyond the Harris Hip Score. Future studies should explore relationships between regional acetabular coverage and specific symptoms, activity limitations, or quality of life measures. Third, our follow-up duration, while sufficient to demonstrate early clinical success, is inadequate for assessing long-term outcomes such as osteoarthritis progression or conversion to total hip arthroplasty. Studies with 10–15 year follow-up are needed to determine whether postoperative ASA values below population thresholds affect long-term joint survival. Fourth, we excluded patients with bilateral dysplasia to enable contralateral hip comparison. This exclusion may limit applicability to the substantial proportion of dysplasia patients with bilateral involvement. Additionally, our assumption that contralateral hips represented "normal" anatomy proved questionable given our findings. Fifth, the Verhaegen et al. threshold values were derived from a different population, potentially limiting direct comparability due to ethnic or anthropometric differences. Establishing population-specific threshold values for diverse geographic regions would strengthen future comparative studies. Sixth, we did not assess functional dynamic coverage or weightbearing alignment, which may influence clinical outcomes independently of static acetabular morphology. Advanced techniques such as dynamic CT or dual fluoroscopy could provide insights into functional coverage during activities. Seventh, we did not account for soft tissue factors, muscle strength, or neuromuscular control, all of which may influence hip stability and symptoms independently of bony morphology. A comprehensive assessment would incorporate these factors. Finally, measurements were obtained from a single postoperative timepoint (6–12 months after surgery). Serial measurements could reveal temporal changes in acetabular position due to bone remodeling or implant micromotion, although such changes are generally minimal with well-fixed osteotomies. Clinical Implications and Future Directions Our findings have several clinical implications. First, surgeons performing PAO should consider three-dimensional acetabular assessment using CT-based ASA measurements for comprehensive surgical planning. Second, achieving acetabular coverage matching the contralateral asymptomatic hip appears to be an acceptable surgical target associated with excellent clinical outcomes, even if coverage remains below population-based dysplasia thresholds. Third, patients with unilateral symptomatic dysplasia should be informed that their contralateral hip may also harbor borderline morphology warranting monitoring, even in the absence of current symptoms. Future research should address several key questions: (1) Do long-term outcomes differ between patients whose postoperative coverage meets versus falls short of population thresholds? (2) Would more aggressive correction to achieve coverage meeting population thresholds provide superior long-term outcomes or potentially increase complication risks? (3) What is the natural history of contralateral hips with borderline dysplastic morphology in patients undergoing unilateral PAO? (4) Do population-specific threshold values differ across ethnic groups? (5) Can machine learning algorithms using comprehensive 3D morphological assessment predict which dysplastic hips will benefit most from PAO versus other interventions? Multicenter collaborative studies with long-term follow-up, incorporating comprehensive 3D imaging, patient-reported outcomes, and activity monitoring, will be essential for answering these questions and further refining our approach to hip preservation surgery. CONCLUSIONS Periacetabular osteotomy significantly improves three-dimensional acetabular coverage, particularly in superior and posterolateral regions, with corresponding excellent clinical outcomes. However, both postoperative operated hips and contralateral asymptomatic hips demonstrate morphological characteristics falling below recently established population-based dysplasia threshold values. This suggests that successful PAO outcomes may not require achieving coverage meeting population thresholds, and that surgical planning should consider patient-specific baseline morphology. Comprehensive preoperative 3D assessment using acetabular sector angles and radar chart visualization facilitates understanding of dysplasia patterns and surgical planning. Contralateral "normal" hips in patients with unilateral symptomatic dysplasia may harbor borderline dysplastic morphology warranting longitudinal monitoring. Long-term studies are needed to determine optimal surgical correction targets and to assess the natural history of borderline morphology. Declarations Clinical trial number Clinical trial number is not applicable. Ethical Approval This study was approved by the Institutional Review Board of Metin Sabanci Baltalimani Bone Diseases Training and Research Hospital, approval number 328, date 10.03.2025. All procedures performed were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Consent to Participate Due to the retrospective nature of this study and the use of anonymized data, the Institutional Review Board waived the requirement for written informed consent. Consent for Publication Not applicable. No individual person's data in any form (including individual details, images, or videos) are included in this manuscript. Declaration of Conflicting Interests The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The authors received no financial support for the research, authorship, and/or publication of this article. Data Availability Statement The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request, subject to institutional data sharing policies and ethical considerations. Author Contributions Study conception and design: Murat Onder, Abdurrahman Aydin Data collection: Murat Onder, Melisa Demir, Avni Ilhan Bayhan Data analysis and interpretation: Avni İlhan Bayhan, Sefa Seluk, Manuscript drafting: Murat Onder,Melisa Demir,Avni Ilhan Bayhan Critical revision and final approval: Murat Onder, Sefa Seluk, Melisa Demir, Avni Ilhan Bayhan, Abdurrahman Aydin References Jha T, Shenava HS, Rajkumar S, Lokesh Agarwal S, Harshavardhan J. 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1","display":"","copyAsset":false,"role":"figure","size":201454,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePatient Selection Flowchart\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCONSORT-style flowchart depicting patient selection process. Of 84 patients initially identified who underwent periacetabular osteotomy between January 2015 and December 2020, 33 met all inclusion criteria and were included in the final analysis. Major exclusion reasons included bilateral dysplasia (n=13), inadequate imaging (n=12), and insufficient follow-up (n=27).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8199721/v1/8ab6d5a0d839e1a8ac166af4.png"},{"id":97895738,"identity":"ac3e5f58-bea4-48e7-94ee-c6505e94ad43","added_by":"auto","created_at":"2025-12-10 15:34:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1179537,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDemonstration of the Method for Measuring Acetabular Sector Angles\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e2a shows the superior acetabular sector angle. Figures 2b, 2c and 2d show the proximal, intermediate and equatorial anterior and posterior acetabular sector angles.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8199721/v1/9e8cd260f21c6badf4dce7a1.png"},{"id":97745661,"identity":"489a131e-78cc-42a6-9459-0fde3e126081","added_by":"auto","created_at":"2025-12-09 00:25:39","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":164761,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRadar Chart Comparing Preoperative and Postoperative Acetabular Sector Angles\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRadar chart demonstrating three-dimensional acetabular coverage pattern before and after periacetabular osteotomy. Each axis represents a different acetabular sector angle measurement. The blue line represents preoperative dysplastic morphology, and the red line represents postoperative improved coverage. Note global improvement in coverage across all regions, with most substantial improvements in superior and proximal posterior sectors.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8199721/v1/9c0db3b88fbe4d0787f2ffcf.png"},{"id":97897316,"identity":"e83db21c-dddb-4d20-a00e-76b6f87b5511","added_by":"auto","created_at":"2025-12-10 15:37:44","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":163285,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRadar Chart Comparing Postoperative Operated Hip with Contralateral Normal Hip\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRadar chart comparing postoperative acetabular coverage of the operated hip (red line) with the contralateral asymptomatic hip (green line). Note the close similarity between the two hips at most anatomical levels, with the operated hip demonstrating greater superior coverage. This suggests successful normalization of acetabular morphology relative to the patient's baseline anatomy.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8199721/v1/4ce14bf67c4c0b4f2de5b37d.png"},{"id":97745659,"identity":"6bb73f13-ef9d-4b6e-8ba4-eaea9d8815e5","added_by":"auto","created_at":"2025-12-09 00:25:39","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":153130,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRadar Chart Comparing Postoperative Operated Hip with Verhaegen Threshold Values\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRadar chart comparing postoperative acetabular coverage of operated hips (red line) with population-based dysplasia threshold values established by Verhaegen et al. (black dashed line). Despite clinical success, postoperative coverage remains below threshold values at most anatomical levels except superior coverage, suggesting that surgical success criteria may differ from population-based norms.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8199721/v1/21a874428b39014a11b413cf.png"},{"id":97745664,"identity":"9d7e9f26-e259-49c9-aded-7fdcfbd650cd","added_by":"auto","created_at":"2025-12-09 00:25:39","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":149462,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRadar Chart Comparing Contralateral Normal Hip with Verhaegen Threshold Values\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRadar chart comparing acetabular coverage of contralateral asymptomatic hips (green line) with Verhaegen dysplasia threshold values (black dashed line). Notably, even these clinically asymptomatic hips with normal radiographic center-edge angles demonstrate morphology below threshold values at most levels, suggesting borderline dysplastic morphology despite absence of symptoms.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8199721/v1/0238f181d6c09d9ce6be4ac5.png"},{"id":97745666,"identity":"60886747-4b41-4b0d-b8fc-561d9c8c34dc","added_by":"auto","created_at":"2025-12-09 00:25:39","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":214630,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eComprehensive Radar Chart Overlay\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRadar chart overlaying all comparison groups: preoperative dysplastic hip (blue line), postoperative operated hip (red line), contralateral asymptomatic hip (green line), and Verhaegen dysplasia threshold values (black dashed line). This comprehensive visualization enables simultaneous comparison of surgical improvement, bilateral symmetry, and relationship to population norms. The chart demonstrates that while PAO substantially improves coverage and approaches contralateral morphology, both hips remain below population-based thresholds at most levels despite excellent clinical outcomes.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8199721/v1/86104bd4e69a883d05e590f4.png"},{"id":100865965,"identity":"32f62bcf-b3f4-46b1-ae40-66409b93ad6c","added_by":"auto","created_at":"2026-01-22 08:27:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4113373,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8199721/v1/e64e44e3-8408-494b-9dbb-fccd6ea74890.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eThree-dimensional Acetabular Coverage Following Periacetabular Osteotomy: Comparison With Population-based Threshold Values Using Acetabular Sector Angles\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003ePeriacetabular osteotomy (PAO) remains the gold standard surgical treatment for preventing or delaying osteoarthritis in young adults with symptomatic acetabular dysplasia.[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] Traditionally, surgical planning and success have been evaluated using the lateral center-edge angle (CEA) of Wiberg measured on anteroposterior (AP) pelvic radiographs, with the goal of achieving adequate superior femoral head coverage.[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eHowever, the acetabulum is a three-dimensional (3D) structure, and relying solely on two-dimensional (2D) radiographic measurements may overlook critical anterior and posterior wall deficiencies.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] The sourcil, representing the weight-bearing dome of the acetabulum on radiographs, provides limited information about circumferential coverage. Furthermore, acetabular version can significantly influence the apparent superior coverage on AP radiographs, potentially leading to inaccurate assessment of true femoral head coverage.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eRecent studies have demonstrated that developmental hip dysplasia is not limited to deficient superior coverage but affects all acetabular walls.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] The Ottawa classification categorizes acetabular dysplasia into anterior, posterior, and global patterns, each associated with distinct clinical symptoms and pathomechanics.[\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] Insufficient anterior coverage may cause pain during hip extension, while posterior deficiency can present with symptoms mimicking piriformis syndrome or sciatica. Additionally, excessive anterior coverage may lead to femoroacetabular impingement and labral tears, while posterior insufficiency predisposes to instability and pain. Ultimately, all these patterns contribute to accelerated cartilage degeneration and osteoarthritis development.[\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eTo address these limitations, the concept of acetabular sector angles (ASA) has been developed, enabling quantitative 3D assessment of acetabular morphology using computed tomography (CT).[\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] Most importantly, Verhaegen and colleagues recently established population-based threshold values for ASA measurements, providing objective criteria for distinguishing dysplastic from normal acetabular morphology.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eDespite the widespread use of PAO and the recent establishment of dysplasia threshold values, no studies have examined how postoperative acetabular coverage relates to these population-based norms. Understanding this relationship is crucial for optimizing surgical correction targets and potentially refining surgical techniques.\u003c/p\u003e\u003cp\u003eThe purpose of this study was to: (1) evaluate changes in 3D acetabular coverage following PAO using ASA measurements at multiple anatomical levels, (2) compare postoperative coverage with contralateral asymptomatic hips, and (3) assess how both operated and contralateral hips relate to recently established dysplasia threshold values. We hypothesized that PAO would significantly improve acetabular coverage across all regions but that postoperative values might still differ from population-based normal thresholds. Additionally, we utilized radar charts for intuitive visualization of 3D acetabular morphology changes.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy Design and Patient Selection\u003c/h2\u003e\u003cp\u003eThis retrospective cross-sectional study was conducted at a single tertiary referral center. The study was approved by the Institutional Review Board (approval number \u003cb\u003e[328]\u003c/b\u003e, approval date \u003cb\u003e[10.2025]\u003c/b\u003e), and the requirement for written informed consent was waived due to the retrospective nature of the study. All procedures were performed in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments.\u003c/p\u003e\u003cp\u003eWe reviewed medical records of all patients who underwent PAO for symptomatic acetabular dysplasia between January 2015 and December 2020. A total of 84 patients were initially identified. Patients were included if they: (1) underwent unilateral PAO for symptomatic acetabular dysplasia, (2) had CEA\u0026thinsp;\u0026lt;\u0026thinsp;20\u0026deg; on preoperative AP pelvic radiographs, (3) had preoperative and postoperative CT scans with adequate image quality, (4) had a contralateral hip with normal CEA (\u0026gt;\u0026thinsp;25\u0026deg;) on radiographs, (5) had spherical femoral head morphology, and (6) had minimum 24-month follow-up.\u003c/p\u003e\u003cp\u003eExclusion criteria were: (1) bilateral hip dysplasia (CEA\u0026thinsp;\u0026lt;\u0026thinsp;20\u0026deg; bilaterally) (n\u0026thinsp;=\u0026thinsp;13), (2) previous hip surgery in childhood (n\u0026thinsp;=\u0026thinsp;7), (3) Perthes disease or other causes of aspherical femoral head (n\u0026thinsp;=\u0026thinsp;2), (4) inadequate preoperative or postoperative CT imaging (n\u0026thinsp;=\u0026thinsp;12), (5) incomplete follow-up data (n\u0026thinsp;=\u0026thinsp;27). Following application of these criteria, 33 patients were included in the final analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe final cohort consisted of 18 females and 15 males with a mean age of 23.4 years (range, 16\u0026ndash;31 years) at the time of surgery. Mean follow-up duration was 62\u0026thinsp;\u0026plusmn;\u0026thinsp;16.4 months (range, 24\u0026ndash;96 months) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePatient Demographics and Clinical Outcomes\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCharacteristic\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eValue\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNumber of patients\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e33\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eGender\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMale\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e15 (45.5%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFemale\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18 (54.5%)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAge at surgery (years)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e23.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2 (16\u0026ndash;31)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFollow-up duration (months)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e62\u0026thinsp;\u0026plusmn;\u0026thinsp;16.4 (24\u0026ndash;96)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHarris Hip Score\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePreoperative\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e56\u0026thinsp;\u0026plusmn;\u0026thinsp;8.3 (38\u0026ndash;72)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePostoperative\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e89\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7 (78\u0026ndash;98)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eChange\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e+\u0026thinsp;33\u0026thinsp;\u0026plusmn;\u0026thinsp;9.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eP-value\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"2\"\u003eData presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD (range) or n (%)\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSurgical Technique\u003c/h3\u003e\n\u003cp\u003eAll PAO procedures were performed by the senior author using the Bernese periacetabular osteotomy technique as described by Ganz et al.[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] The surgery involves four osteotomy cuts: (1) supra-acetabular, (2) infra-acetabular (ischial), (3) posterior column, and (4) anterior column (pubic), allowing reorientation of the acetabular fragment to improve femoral head coverage. The acetabular fragment was mobilized and repositioned to achieve a target postoperative CEA of 30\u0026ndash;35\u0026deg;, ensuring femoral head coverage without causing femoroacetabular impingement. Fixation was achieved using 3\u0026ndash;4 cortical screws. All patients followed a standardized rehabilitation protocol including protected weight-bearing for 8 weeks postoperatively.\u003c/p\u003e\n\u003ch3\u003eCT Imaging Protocol and Standardization\u003c/h3\u003e\n\u003cp\u003eAll patients underwent pelvic CT scanning using standardized protocols (120 kVp, automatic mA modulation, 1-mm slice thickness, 0.5-mm increment) on 64-slice or 128-slice multidetector CT scanners (GE Healthcare or Siemens Healthineers). Images were obtained with patients in supine position with feet internally rotated 15\u0026deg;. Preoperative CT scans were performed within 2 weeks before surgery, and postoperative CT scans were obtained at minimum 6 months following surgery (mean 8.3 months, range 6\u0026ndash;12 months) to allow for bone healing and remodeling.\u003c/p\u003e\n\u003ch3\u003eAcetabular Sector Angle Measurements\u003c/h3\u003e\n\u003cp\u003eAll measurements were performed using a dedicated PACS workstation (Extreme PACS, RADinfo Systems Inc.) with multiplanar reformation (MPR) capabilities by two experienced observers: a fellowship-trained musculoskeletal radiologist with 10 years of experience and an experienced hip preservation surgeon. To eliminate measurement errors from pelvic tilt, standardized axial planes were established using MPR following the methodology described by Verhaegen et al.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eThe axial plane was adjusted to pass through both femoral head centers, ensuring consistent measurement planes across all patients. ASA measurements were obtained at four standardized levels as described by Verhaegen et al.:[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eEquatorial Level\u003c/b\u003e: Axial slice through the true femoral head center (largest femoral head diameter)\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eIntermediate Level\u003c/b\u003e: Midway between equatorial and proximal levels\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eProximal Level\u003c/b\u003e: Most superior axial slice through the femoral head center\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eSuperior Level\u003c/b\u003e: Measured on coronal reformatted images\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003cp\u003eFor each axial level, anterior ASA (AASA) and posterior ASA (PASA) were measured. ASA was defined as the angle between: (1) a line connecting both femoral head centers, and (2) a line from the ipsilateral femoral head center to the anterior or posterior acetabular rim. Superior ASA (sup. ASA) was measured on coronal images as the angle between the line connecting femoral head centers and the line to the superolateral acetabular rim.\u003c/p\u003e\u003cp\u003eThe following nine angles were recorded for each hip:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eSuperior ASA (sup. ASA)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eProximal anterior ASA (prox. AASA)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eProximal posterior ASA (prox. PASA)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eIntermediate anterior ASA (inter. AASA)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eIntermediate posterior ASA (inter. PASA)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eEquatorial anterior ASA (equat. AASA)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eEquatorial posterior ASA (equat. PASA)\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eAdditionally, the lateral center-edge angle (CEA) was measured on AP pelvic radiographs according to the method described by Wiberg.[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eAll measurements were performed for: (1) dysplastic hips preoperatively, (2) operated hips postoperatively, and (3) contralateral asymptomatic hips. The contralateral hip measurements served as an internal control, representing the patient's baseline acetabular morphology.\u003c/p\u003e\n\u003ch3\u003eClinical Outcome Assessment\u003c/h3\u003e\n\u003cdiv class=\"Heading\"\u003eClinical Outcome Assessment\u003c/div\u003e\u003cp\u003eHarris Hip Scores (HHS) were recorded preoperatively and at final follow-up by an independent assessor blinded to the imaging measurements. The HHS ranges from 0 to 100, with higher scores indicating better hip function.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eReliability Assessment\u003c/h2\u003e\u003cp\u003eTo assess measurement reliability, the primary observer (musculoskeletal radiologist) repeated all measurements after a 10-day washout period, blinded to initial values. The secondary observer (hip preservation surgeon) independently performed measurements on identical images. Intraclass correlation coefficients (ICCs) with 95% confidence intervals were calculated for all measurements. ICC values were interpreted as follows: poor (\u0026lt;\u0026thinsp;0.40), fair (0.40\u0026ndash;0.59), good (0.60\u0026ndash;0.74), or excellent (\u0026ge;\u0026thinsp;0.75).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eStatistical analyses were performed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA). Normality of continuous variables was assessed using the Shapiro-Wilk test. Descriptive statistics included means, standard deviations, and ranges for continuous variables, and frequencies and percentages for categorical variables.\u003c/p\u003e\u003cp\u003ePaired comparisons between preoperative and postoperative measurements in the operated hip were performed using paired t-tests for normally distributed variables or Wilcoxon signed-rank tests for non-normally distributed variables. Similarly, paired comparisons between postoperative operated hips and contralateral asymptomatic hips were performed using the same approach.\u003c/p\u003e\u003cp\u003eEffect sizes were calculated using Cohen's d, interpreted as small (0.2\u0026ndash;0.49), medium (0.5\u0026ndash;0.79), or large (\u0026ge;\u0026thinsp;0.8). Given the exploratory nature of some comparisons, no correction for multiple comparisons was applied, but we note this as a limitation.\u003c/p\u003e\u003cp\u003eFor comparison with Verhaegen et al.'s threshold values,[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] we calculated the proportion of hips (preoperative, postoperative, and contralateral) that met or exceeded each threshold value for dysplasia.\u003c/p\u003e\u003cp\u003eAll statistical tests were two-tailed, and statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05. ICC values were calculated using a two-way random effects model for absolute agreement.\u003c/p\u003e\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eClinical Outcomes\u003c/h2\u003e\u003cp\u003eHarris Hip Scores improved significantly from a mean of 56 preoperatively (range, 38\u0026ndash;72) to 89 postoperatively (range, 78\u0026ndash;98) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, 95% CI: 28.5\u0026ndash;37.5), representing a mean improvement of 33 points. All patients reported satisfaction with the surgical outcome at final follow-up, and no patient required conversion to total hip arthroplasty during the follow-up period.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eRadiographic Outcomes\u003c/h2\u003e\u003cp\u003eThe lateral center-edge angle of Wiberg increased significantly from a mean of 13.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.35\u0026deg; preoperatively to 38.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.33\u0026deg; postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, 95% CI: 22.1\u0026ndash;29.1, Cohen's d\u0026thinsp;=\u0026thinsp;2.91), representing excellent correction of superior coverage.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eThree-Dimensional Acetabular Coverage Changes\u003c/h2\u003e\u003cdiv id=\"Sec14\" class=\"Section3\"\u003e\u003ch2\u003ePreoperative Versus Postoperative Comparisons (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of Acetabular Sector Angle Values Before and After Periacetabular Osteotomy\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePostoperative (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eChange (Δ)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e95% CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eCohen's d\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWiberg CEA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e13.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e38.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e+\u0026thinsp;25.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e22.1\u0026ndash;29.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.91\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSup. ASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e108.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e129.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e+\u0026thinsp;20.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e14.8\u0026ndash;26.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.92\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eProx. AASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e66.9\u0026thinsp;\u0026plusmn;\u0026thinsp;22.97\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e78.8\u0026thinsp;\u0026plusmn;\u0026thinsp;29.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e+\u0026thinsp;11.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.025\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.6\u0026ndash;22.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.44\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eProx. PASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e92.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e114.6\u0026thinsp;\u0026plusmn;\u0026thinsp;15.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e+\u0026thinsp;21.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e14.2\u0026ndash;29.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.46\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eInter. AASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e48.3\u0026thinsp;\u0026plusmn;\u0026thinsp;13.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e57.2\u0026thinsp;\u0026plusmn;\u0026thinsp;25.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e+\u0026thinsp;8.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.086\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-1.3-19.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.42\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eInter. PASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e89.4\u0026thinsp;\u0026plusmn;\u0026thinsp;12.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e100.7\u0026thinsp;\u0026plusmn;\u0026thinsp;17.97\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e+\u0026thinsp;11.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.003\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e4.2\u0026ndash;18.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.72\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEquat. AASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e39.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e43.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e+\u0026thinsp;3.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.268\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e-3.1-10.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.29\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEquat. PASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e84.2\u0026thinsp;\u0026plusmn;\u0026thinsp;12.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e92.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e+\u0026thinsp;8.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.010\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e2.3\u0026ndash;14.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003eCEA\u0026thinsp;=\u0026thinsp;center-edge angle; ASA\u0026thinsp;=\u0026thinsp;acetabular sector angle; Sup. = superior; Prox. = proximal; Inter. = intermediate; Equat. = equatorial; AASA\u0026thinsp;=\u0026thinsp;anterior acetabular sector angle; PASA\u0026thinsp;=\u0026thinsp;posterior acetabular sector angle; SD\u0026thinsp;=\u0026thinsp;standard deviation; CI\u0026thinsp;=\u0026thinsp;confidence interval.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003eStatistical comparisons performed using paired t-tests for normally distributed variables or Wilcoxon signed-rank tests for non-normally distributed variables.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eSuperior ASA demonstrated the largest increase, from 108.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.04\u0026deg; preoperatively to 129.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.55\u0026deg; postoperatively, representing a mean increase of 20.5\u0026deg; (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, 95% CI: 14.8\u0026ndash;26.2, Cohen's d\u0026thinsp;=\u0026thinsp;1.92). This finding confirms that PAO primarily enhances superolateral coverage, which correlates with the improvement in radiographic CEA.\u003c/p\u003e\u003cp\u003eAt the proximal level, both anterior and posterior coverage improved significantly. Proximal PASA increased from 92.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.96\u0026deg; to 114.6\u0026thinsp;\u0026plusmn;\u0026thinsp;15.22\u0026deg;, a mean increase of 21.8\u0026deg; (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, 95% CI: 14.2\u0026ndash;29.4, Cohen's d\u0026thinsp;=\u0026thinsp;1.46). Proximal AASA increased from 66.9\u0026thinsp;\u0026plusmn;\u0026thinsp;22.97\u0026deg; to 78.8\u0026thinsp;\u0026plusmn;\u0026thinsp;29.25\u0026deg;, a mean increase of 11.9\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.025, 95% CI: 1.6\u0026ndash;22.2, Cohen's d\u0026thinsp;=\u0026thinsp;0.44).\u003c/p\u003e\u003cp\u003eAt the intermediate level, posterior coverage showed significant improvement with inter. PASA increasing from 89.4\u0026thinsp;\u0026plusmn;\u0026thinsp;12.42\u0026deg; to 100.7\u0026thinsp;\u0026plusmn;\u0026thinsp;17.97\u0026deg;, a mean increase of 11.3\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.003, 95% CI: 4.2\u0026ndash;18.4, Cohen's d\u0026thinsp;=\u0026thinsp;0.72). However, intermediate anterior coverage (inter. AASA) demonstrated a trend toward improvement that did not reach statistical significance (48.3\u0026thinsp;\u0026plusmn;\u0026thinsp;13.76\u0026deg; to 57.2\u0026thinsp;\u0026plusmn;\u0026thinsp;25.22\u0026deg;, mean increase 8.9\u0026deg;, p\u0026thinsp;=\u0026thinsp;0.086, 95% CI: -1.3 to 19.1, Cohen's d\u0026thinsp;=\u0026thinsp;0.42).\u003c/p\u003e\u003cp\u003eAt the equatorial level, equatorial PASA increased from 84.2\u0026thinsp;\u0026plusmn;\u0026thinsp;12.41\u0026deg; to 92.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.18\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.010, 95% CI: 2.3\u0026ndash;14.9, Cohen's d\u0026thinsp;=\u0026thinsp;0.65), while equatorial AASA showed a non-significant trend toward improvement (39.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.71\u0026deg; to 43.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.41\u0026deg;, p\u0026thinsp;=\u0026thinsp;0.268, 95% CI: -3.1 to 10.9, Cohen's d\u0026thinsp;=\u0026thinsp;0.29).\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003ePostoperative Versus Contralateral Normal Hip Comparisons (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of Postoperative Acetabular Coverage with Contralateral Normal Hip and Verhaegen Threshold Values\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePostoperative Operated Hip (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eContralateral Normal Hip (Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e95% CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eVerhaegen Threshold for Dysplasia\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eOperated Hip vs Threshold (Δ)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eContralateral Hip vs Threshold (Δ)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWiberg CEA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e38.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e29.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.006\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e3.1\u0026ndash;15.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e25\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e+\u0026thinsp;13.9\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e+\u0026thinsp;4.4\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSup. ASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e129.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e118.0\u0026thinsp;\u0026plusmn;\u0026thinsp;13.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e5.8\u0026ndash;16.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e116\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e+\u0026thinsp;13.0\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e+\u0026thinsp;2.0\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eProx. AASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e78.8\u0026thinsp;\u0026plusmn;\u0026thinsp;29.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e89.5\u0026thinsp;\u0026plusmn;\u0026thinsp;25.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.213\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-6.1-27.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e133\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-54.2\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e-43.5\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eProx. PASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e114.6\u0026thinsp;\u0026plusmn;\u0026thinsp;15.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e110.6\u0026thinsp;\u0026plusmn;\u0026thinsp;18.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.462\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-6.9-14.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e137\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-22.4\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e-26.4\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eInter. AASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e57.2\u0026thinsp;\u0026plusmn;\u0026thinsp;25.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e60.3\u0026thinsp;\u0026plusmn;\u0026thinsp;15.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.535\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-6.7-12.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e72\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-14.8\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e-11.7\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eInter. PASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e100.7\u0026thinsp;\u0026plusmn;\u0026thinsp;17.97\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e97.3\u0026thinsp;\u0026plusmn;\u0026thinsp;13.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.598\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-9.2-15.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e107\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-6.3\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e-9.7\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEquat. AASA (\u0026deg;)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e43.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e50.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.041\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.3\u0026ndash;12.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e57\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-13.2\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e-6.9\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEquat. PASA (\u0026deg;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e92.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e95.2\u0026thinsp;\u0026plusmn;\u0026thinsp;9.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.554\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e-5.6-10.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e97\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e-4.2\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e-1.8\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"8\"\u003eCEA\u0026thinsp;=\u0026thinsp;center-edge angle; ASA\u0026thinsp;=\u0026thinsp;acetabular sector angle; Sup. = superior; Prox. = proximal; Inter. = intermediate; Equat. = equatorial; AASA\u0026thinsp;=\u0026thinsp;anterior acetabular sector angle; PASA\u0026thinsp;=\u0026thinsp;posterior acetabular sector angle; SD\u0026thinsp;=\u0026thinsp;standard deviation; CI\u0026thinsp;=\u0026thinsp;confidence interval.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"8\"\u003eStatistical comparisons between postoperative operated hip and contralateral normal hip performed using paired t-tests or Wilcoxon signed-rank tests as appropriate.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"8\"\u003eVerhaegen threshold values represent the minimum values distinguishing normal from dysplastic hips as established by Verhaegen et al. (2023).[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] Negative delta values indicate coverage below the dysplasia threshold.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eWhen comparing postoperative operated hips to contralateral asymptomatic hips, interesting patterns emerged. The superior ASA was significantly greater in operated hips (129.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.55\u0026deg; vs. 118.0\u0026thinsp;\u0026plusmn;\u0026thinsp;13.71\u0026deg;, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, 95% CI: 5.8\u0026ndash;16.2), indicating that surgical correction resulted in superior coverage exceeding the contralateral hip.\u003c/p\u003e\u003cp\u003eHowever, at other anatomical levels, no significant differences were observed between postoperative operated hips and contralateral asymptomatic hips:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eProx. AASA: 78.8\u0026thinsp;\u0026plusmn;\u0026thinsp;29.25\u0026deg; vs. 89.5\u0026thinsp;\u0026plusmn;\u0026thinsp;25.89\u0026deg;, p\u0026thinsp;=\u0026thinsp;0.213\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eProx. PASA: 114.6\u0026thinsp;\u0026plusmn;\u0026thinsp;15.22\u0026deg; vs. 110.6\u0026thinsp;\u0026plusmn;\u0026thinsp;18.31\u0026deg;, p\u0026thinsp;=\u0026thinsp;0.462\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eInter. AASA: 57.2\u0026thinsp;\u0026plusmn;\u0026thinsp;25.22\u0026deg; vs. 60.3\u0026thinsp;\u0026plusmn;\u0026thinsp;15.70\u0026deg;, p\u0026thinsp;=\u0026thinsp;0.535\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eInter. PASA: 100.7\u0026thinsp;\u0026plusmn;\u0026thinsp;17.97\u0026deg; vs. 97.3\u0026thinsp;\u0026plusmn;\u0026thinsp;13.56\u0026deg;, p\u0026thinsp;=\u0026thinsp;0.598\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eEquat. PASA: 92.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.18\u0026deg; vs. 95.2\u0026thinsp;\u0026plusmn;\u0026thinsp;9.19\u0026deg;, p\u0026thinsp;=\u0026thinsp;0.554\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eThe only significant difference besides superior coverage was at the equatorial anterior level, where contralateral hips demonstrated greater coverage (43.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.41\u0026deg; vs. 50.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.73\u0026deg;, p\u0026thinsp;=\u0026thinsp;0.041, 95% CI: 0.3\u0026ndash;12.3).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003eComparison with Population-Based Threshold Values (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/h2\u003e\u003cp\u003eWhen comparing both postoperative operated hips and contralateral asymptomatic hips to the dysplasia threshold values established by Verhaegen et al.,[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] a striking finding emerged: both groups fell substantially below the threshold values at most anatomical levels.\u003c/p\u003e\u003cp\u003eFor postoperative operated hips:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eSup. ASA: 129.0\u0026deg; vs. threshold 116\u0026deg; (exceeded threshold)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eProx. AASA: 78.8\u0026deg; vs. threshold 133\u0026deg; (54\u0026deg; below threshold)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eProx. PASA: 114.6\u0026deg; vs. threshold 137\u0026deg; (22.4\u0026deg; below threshold)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eInter. AASA: 57.2\u0026deg; vs. threshold 72\u0026deg; (14.8\u0026deg; below threshold)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eInter. PASA: 100.7\u0026deg; vs. threshold 107\u0026deg; (6.3\u0026deg; below threshold)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eEquat. AASA: 43.8\u0026deg; vs. threshold 57\u0026deg; (13.2\u0026deg; below threshold)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eEquat. PASA: 92.8\u0026deg; vs. threshold 97\u0026deg; (4.2\u0026deg; below threshold)\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eSimilar patterns were observed for contralateral asymptomatic hips, which also consistently fell below threshold values at most levels except superior coverage.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003eRadar Chart Visualization (Figs.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e)\u003c/h2\u003e\u003cp\u003eRadar charts provided intuitive visualization of the 3D acetabular coverage patterns (Figs.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e). These charts clearly demonstrated:\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eGlobal improvement in acetabular coverage following PAO (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eNear-symmetry between postoperative operated hips and contralateral asymptomatic hips (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003ePersistent deficiency relative to population-based thresholds in both postoperative operated and contralateral asymptomatic hips (Figs.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003e)\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eOverlaid comparison showing all groups simultaneously (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e)\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\u003ch2\u003eReliability Analysis\u003c/h2\u003e\u003cp\u003eIntraobserver ICC values ranged from 0.82 to 0.94, and interobserver ICC values ranged from 0.78 to 0.91 demonstrating high reliability of the measurement technique.\u003c/p\u003e\u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study demonstrates that PAO significantly improves three-dimensional acetabular coverage, particularly in the superior, posterolateral and superiolateral regions, with corresponding improvements in clinical outcomes. However, we identified an unexpected finding: both postoperative operated hips and contralateral \"normal\" hips demonstrated acetabular morphology that fell below recently established population-based threshold values for dysplasia at most anatomical levels. This raises important questions about the relationship between acetabular morphology, clinical symptoms, and surgical success criteria.\u003c/p\u003e\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\u003ch2\u003eThree-Dimensional Assessment of Acetabular Dysplasia\u003c/h2\u003e\u003cp\u003eTraditional two-dimensional radiographic assessment of hip dysplasia, while convenient and widely available, provides limited information about the true three-dimensional nature of acetabular deficiency.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] Our findings support previous work demonstrating that dysplasia affects not only the superior dome but also the anterior and posterior walls.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] The Ottawa classification has highlighted the clinical relevance of these regional differences, with anterior deficiency causing extension-related pain and posterior deficiency presenting with symptoms that may be misattributed to lumbosacral pathology.[\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eThe use of acetabular sector angles measured on CT scans enables comprehensive quantitative assessment of acetabular morphology at multiple anatomical levels.[\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] In our cohort, preoperative dysplastic hips demonstrated deficiencies across all measured regions, not limited to superior coverage. This underscores the importance of considering the entire acetabular perimeter when planning and executing corrective surgery.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\u003ch2\u003eEfficacy of Periacetabular Osteotomy\u003c/h2\u003e\u003cp\u003eOur results demonstrate that PAO effectively improves acetabular coverage across multiple regions, with the most substantial improvements occurring in superior and posterior coverage at the proximal level. The mean increase of 20.5\u0026deg; in superior ASA and 21.8\u0026deg; in proximal posterior ASA represents clinically meaningful improvement, consistent with the surgical goal of reorienting the acetabulum to better contain the femoral head.\u003c/p\u003e\u003cp\u003eThese findings align with previous studies demonstrating that PAO enhances superolateral and anterolateral femoral head coverage.[\u003cspan additionalcitationids=\"CR17 CR18 CR19\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] The improvement in Harris Hip Scores from 56 to 89 confirms that these morphological improvements translate into meaningful clinical benefit, consistent with excellent long-term outcomes reported in other PAO series.[\u003cspan additionalcitationids=\"CR30\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eInterestingly, while anterior coverage improved at the proximal level, the improvements at intermediate and equatorial levels were more modest and inconsistent. This may reflect technical limitations of the PAO technique or surgical philosophy prioritizing superior and posterior correction. Future studies should explore whether more aggressive anterior correction at lower levels would provide additional clinical benefit or potentially cause anterior femoroacetabular impingement.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec22\" class=\"Section2\"\u003e\u003ch2\u003eThe \"Normal\" Contralateral Hip Paradox\u003c/h2\u003e\u003cp\u003eOne of the most striking findings of this study is that contralateral asymptomatic hips, which served as internal controls and met traditional radiographic criteria for normal morphology (CEA\u0026thinsp;\u0026gt;\u0026thinsp;25\u0026deg;), nevertheless demonstrated acetabular sector angles substantially below the dysplasia thresholds established by Verhaegen et al.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] in a large population-based study.\u003c/p\u003e\u003cp\u003eSeveral explanations for this discrepancy warrant consideration:\u003c/p\u003e\u003cp\u003eFirst, patients with symptomatic unilateral dysplasia may have a genetic or developmental predisposition affecting both hips, even when only one hip becomes clinically symptomatic. Studies have shown that 30\u0026ndash;40% of patients with unilateral symptomatic dysplasia eventually develop symptoms in the contralateral hip.[\u003cspan additionalcitationids=\"CR23 CR24\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] Our finding suggests that many contralateral \"normal\" hips may represent borderline or mild dysplasia that has not yet become symptomatic due to better compensatory mechanisms, lower activity levels, or shorter duration of loading.\u003c/p\u003e\u003cp\u003eSecond, there may be population-specific variations in normal acetabular morphology. Verhaegen et al.'s thresholds were derived from a North American population,[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] while our study was conducted in Turkey. Anthropometric differences between populations could influence normal acetabular architecture, although previous studies have not consistently demonstrated substantial ethnic variations in acetabular morphology.\u003c/p\u003e\u003cp\u003eThird, the presence of asymptomatic morphological abnormalities is well-recognized in hip pathology. Similarly, acetabular morphology falling below theoretical dysplasia thresholds may not necessarily become symptomatic, depending on activity demands, neuromuscular function, and cartilage quality.\u003c/p\u003e\u003cdiv id=\"Sec23\" class=\"Section3\"\u003e\u003ch2\u003eImplications for Surgical Planning and Success Criteria\u003c/h2\u003e\u003cp\u003eOur findings suggest that the goal of PAO may not be to achieve acetabular morphology meeting population-based dysplasia thresholds, but rather to improve coverage to levels approaching the patient's contralateral hip while ensuring adequate superior dome coverage to prevent progression to osteoarthritis. This patient-specific approach recognizes that individual baseline morphology may differ from population norms.\u003c/p\u003e\u003cp\u003eThe excellent clinical outcomes achieved in our cohort, despite postoperative ASA values remaining below Verhaegen's thresholds at most levels, supports this concept. Patients improved dramatically from a mean Harris Hip Score of 56 (poor) to 89 (excellent), with postoperative coverage similar to their contralateral asymptomatic hips. This suggests that matching or slightly exceeding the contralateral hip morphology may represent an appropriate surgical target for PAO, rather than striving to achieve population-based threshold values.\u003c/p\u003e\u003cp\u003eHowever, this interpretation requires cautious validation. Long-term follow-up studies are needed to determine whether patients whose postoperative coverage remains below population thresholds experience different long-term outcomes compared to those meeting these thresholds. Additionally, the finding that contralateral hips are below thresholds suggests these patients may benefit from preventive interventions or close monitoring, even in the absence of current symptoms.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec24\" class=\"Section2\"\u003e\u003ch2\u003eUtility of Radar Chart Visualization\u003c/h2\u003e\u003cp\u003eThe radar charts used in this study provide an intuitive method for visualizing the complex three-dimensional nature of acetabular coverage. Unlike tables of numerical data, radar charts enable immediate visual appreciation of coverage patterns, regional deficiencies, and the global nature of coverage changes following surgery. This visualization tool may prove valuable for surgical planning, patient education, and comparative research.\u003c/p\u003e\u003cp\u003eTamura et al. previously demonstrated that dysplastic hips exhibit cartilage degeneration primarily in lateral and anterosuperior regions, with persistent labral damage in areas of anterior under-coverage.[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] Igei et al. used similar radar charts to demonstrate comprehensive improvement in acetabular coverage following curved PAO.[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] Our study extends this work by comparing postoperative coverage not only with preoperative and contralateral values but also with population-based threshold values, providing a more complete picture of acetabular morphology optimization.\u003c/p\u003e\u003cdiv id=\"Sec25\" class=\"Section3\"\u003e\u003ch2\u003eComparison with Previous Literature\u003c/h2\u003e\u003cp\u003eIgei et al. evaluated 3D femoral head coverage before and after curved PAO using radar charts, demonstrating improvement in coverage across all regions.[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] However, their study used contralateral asymptomatic hips as the normal comparison group, without considering that these hips might themselves represent borderline dysplasia. Our study advances this understanding by incorporating population-based threshold values as an additional reference point.\u003c/p\u003e\u003cp\u003eVerhaegen et al.'s landmark study established ASA threshold values by comparing 251 asymptomatic hips with 72 dysplastic hips requiring PAO, using receiver operating characteristic analysis to determine optimal cutoff values distinguishing these groups.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] Notably, our study is the first to compare postoperative PAO coverage with these threshold values, revealing the important finding that even successful surgical correction may not achieve coverage meeting these thresholds.\u003c/p\u003e\u003cp\u003eRecent studies have emphasized the importance of three-dimensional surgical planning and intraoperative navigation for optimizing PAO correction.[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] Schwarz et al. described a navigation method using external fixation that enables real-time assessment of three-dimensional acetabular reorientation.[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] Our findings support the value of three-dimensional assessment but suggest that surgical targets should be individualized rather than aiming for a single set of population-based threshold values.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec26\" class=\"Section3\"\u003e\u003ch2\u003eLimitations\u003c/h2\u003e\u003cp\u003eSeveral limitations warrant acknowledgment. First, the retrospective single-center design and relatively modest sample size limit generalizability. Although our sample size provided adequate statistical power for detecting the observed differences, a larger multicenter cohort would strengthen confidence in these findings and enable subgroup analyses by age, gender, or dysplasia severity.\u003c/p\u003e\u003cp\u003eSecond, the study did not correlate specific ASA measurements with functional outcomes or patient-reported outcome measures beyond the Harris Hip Score. Future studies should explore relationships between regional acetabular coverage and specific symptoms, activity limitations, or quality of life measures.\u003c/p\u003e\u003cp\u003eThird, our follow-up duration, while sufficient to demonstrate early clinical success, is inadequate for assessing long-term outcomes such as osteoarthritis progression or conversion to total hip arthroplasty. Studies with 10\u0026ndash;15 year follow-up are needed to determine whether postoperative ASA values below population thresholds affect long-term joint survival.\u003c/p\u003e\u003cp\u003eFourth, we excluded patients with bilateral dysplasia to enable contralateral hip comparison. This exclusion may limit applicability to the substantial proportion of dysplasia patients with bilateral involvement. Additionally, our assumption that contralateral hips represented \"normal\" anatomy proved questionable given our findings.\u003c/p\u003e\u003cp\u003eFifth, the Verhaegen et al. threshold values were derived from a different population, potentially limiting direct comparability due to ethnic or anthropometric differences. Establishing population-specific threshold values for diverse geographic regions would strengthen future comparative studies.\u003c/p\u003e\u003cp\u003eSixth, we did not assess functional dynamic coverage or weightbearing alignment, which may influence clinical outcomes independently of static acetabular morphology. Advanced techniques such as dynamic CT or dual fluoroscopy could provide insights into functional coverage during activities.\u003c/p\u003e\u003cp\u003eSeventh, we did not account for soft tissue factors, muscle strength, or neuromuscular control, all of which may influence hip stability and symptoms independently of bony morphology. A comprehensive assessment would incorporate these factors.\u003c/p\u003e\u003cp\u003eFinally, measurements were obtained from a single postoperative timepoint (6\u0026ndash;12 months after surgery). Serial measurements could reveal temporal changes in acetabular position due to bone remodeling or implant micromotion, although such changes are generally minimal with well-fixed osteotomies.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec27\" class=\"Section3\"\u003e\u003ch2\u003eClinical Implications and Future Directions\u003c/h2\u003e\u003cp\u003eOur findings have several clinical implications. First, surgeons performing PAO should consider three-dimensional acetabular assessment using CT-based ASA measurements for comprehensive surgical planning. Second, achieving acetabular coverage matching the contralateral asymptomatic hip appears to be an acceptable surgical target associated with excellent clinical outcomes, even if coverage remains below population-based dysplasia thresholds. Third, patients with unilateral symptomatic dysplasia should be informed that their contralateral hip may also harbor borderline morphology warranting monitoring, even in the absence of current symptoms.\u003c/p\u003e\u003cp\u003eFuture research should address several key questions: (1) Do long-term outcomes differ between patients whose postoperative coverage meets versus falls short of population thresholds? (2) Would more aggressive correction to achieve coverage meeting population thresholds provide superior long-term outcomes or potentially increase complication risks? (3) What is the natural history of contralateral hips with borderline dysplastic morphology in patients undergoing unilateral PAO? (4) Do population-specific threshold values differ across ethnic groups? (5) Can machine learning algorithms using comprehensive 3D morphological assessment predict which dysplastic hips will benefit most from PAO versus other interventions?\u003c/p\u003e\u003cp\u003eMulticenter collaborative studies with long-term follow-up, incorporating comprehensive 3D imaging, patient-reported outcomes, and activity monitoring, will be essential for answering these questions and further refining our approach to hip preservation surgery.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003ePeriacetabular osteotomy significantly improves three-dimensional acetabular coverage, particularly in superior and posterolateral regions, with corresponding excellent clinical outcomes. However, both postoperative operated hips and contralateral asymptomatic hips demonstrate morphological characteristics falling below recently established population-based dysplasia threshold values. This suggests that successful PAO outcomes may not require achieving coverage meeting population thresholds, and that surgical planning should consider patient-specific baseline morphology. Comprehensive preoperative 3D assessment using acetabular sector angles and radar chart visualization facilitates understanding of dysplasia patterns and surgical planning. Contralateral \"normal\" hips in patients with unilateral symptomatic dysplasia may harbor borderline dysplastic morphology warranting longitudinal monitoring. Long-term studies are needed to determine optimal surgical correction targets and to assess the natural history of borderline morphology.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eClinical trial number\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Clinical trial number is\u0026nbsp;not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Institutional Review Board of Metin Sabanci Baltalimani Bone Diseases Training and Research Hospital, approval number 328, date 10.03.2025. All procedures performed were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDue to the retrospective nature of this study and the use of anonymized data, the Institutional Review Board waived the requirement for written informed consent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. No individual person\u0026apos;s data in any form (including individual details, images, or videos) are included in this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Conflicting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors received no financial support for the research, authorship, and/or publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are available from the corresponding author on reasonable request, subject to institutional data sharing policies and ethical considerations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eStudy conception and design: Murat Onder, Abdurrahman Aydin\u003c/li\u003e\n \u003cli\u003eData collection: Murat Onder, Melisa Demir, Avni Ilhan Bayhan\u003c/li\u003e\n \u003cli\u003eData analysis and interpretation: Avni İlhan Bayhan, Sefa Seluk,\u003c/li\u003e\n \u003cli\u003eManuscript drafting: Murat Onder,Melisa Demir,Avni Ilhan Bayhan\u003c/li\u003e\n \u003cli\u003eCritical revision and final approval: Murat Onder, Sefa Seluk, Melisa Demir, Avni Ilhan Bayhan, Abdurrahman Aydin\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eJha T, Shenava HS, Rajkumar S, Lokesh Agarwal S, Harshavardhan J. 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Intermediate to long-term results following the Bernese periacetabular osteotomy and predictors of clinical outcome. J Bone Joint Surg Am. 2009;91(9):2113\u0026ndash;23. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2106/JBJS.H.00620\u003c/span\u003e\u003cspan address=\"10.2106/JBJS.H.00620\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"hip dysplasia, periacetabular osteotomy, acetabular sector angle, three-dimensional imaging, computed tomography","lastPublishedDoi":"10.21203/rs.3.rs-8199721/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8199721/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003ePeriacetabular osteotomy (PAO) is a complex joint-preserving surgery for acetabular dysplasia. While traditionally focused on achieving superior femoral head coverage, the three-dimensional (3D) nature of acetabular morphology requires comprehensive assessment. Recently established population-based threshold values for acetabular sector angles (ASA) enable quantitative evaluation of dysplasia, but their relationship to post-PAO coverage remains unexplored.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis retrospective cross-sectional study included 33 patients (18 females, 15 males; mean age 23.4 years) who underwent unilateral PAO between January 2015 and December 2020. Preoperative and postoperative ASA measurements were obtained from standardized CT scans at four anatomical levels: superior, proximal, intermediate, and equatorial. Values were compared with contralateral normal hips and recently published dysplasia threshold values. Harris Hip Scores were recorded pre- and postoperatively.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eHarris Hip Scores improved significantly from 56 to 89 postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Superior ASA increased from 108.5\u0026deg; to 129.0\u0026deg; (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, Cohen's d\u0026thinsp;=\u0026thinsp;1.92). Proximal posterior ASA increased by 21.8\u0026deg; (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and proximal anterior ASA by 11.9\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.025). Postoperative coverage approached contralateral hip values but remained below population-based thresholds for dysplasia at most levels. Notably, contralateral \"normal\" hips also fell below established thresholds.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003ePAO significantly improves 3D acetabular coverage, particularly in superior, posterolateral and superiolateral regions. However, both operated and contralateral hips demonstrate morphological features below population-based dysplasia thresholds, suggesting that surgical success criteria may differ from population norms. Radar chart visualization facilitates comprehensive assessment of acetabular morphology for surgical planning.\u003c/p\u003e","manuscriptTitle":"Three-dimensional Acetabular Coverage Following Periacetabular Osteotomy: Comparison With Population-based Threshold Values Using Acetabular Sector Angles","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-09 00:25:34","doi":"10.21203/rs.3.rs-8199721/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9c11f036-20e2-4504-8c8f-9809ee8fefcf","owner":[],"postedDate":"December 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-22T08:25:28+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-09 00:25:34","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8199721","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8199721","identity":"rs-8199721","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}