Effect of Pelvic Compensation Capacity on Proximal Junctional Kyphosis: A Stratified Analysis of Pelvic Tilt in Adult Spinal Deformity Surgery

Effect of Pelvic Compensation Capacity on Proximal Junctional Kyphosis: A Stratified Analysis of Pelvic Tilt in Adult Spinal Deformity Surgery | 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 Effect of Pelvic Compensation Capacity on Proximal Junctional Kyphosis: A Stratified Analysis of Pelvic Tilt in Adult Spinal Deformity Surgery Yanjie Xu, Changsheng Fan, Dongyue Li, Jie Li, Chen Ling, Hui Xu, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6361426/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Jul, 2025 Read the published version in Journal of Orthopaedic Surgery and Research → Version 1 posted 10 You are reading this latest preprint version Abstract Background: Pelvic compensation, as quantified by the pelvic tilt (PT), has been identified as a crucial compensatory mechanism in patients with adult spinal deformity (ASD). However, it remains uncertain whether PT has important roles in predicting the occurrence of proximal junctional kyphosis (PJK). Therefore, the purpose of this study is to analyze the influence of pelvic compensation, specifically PT, on the development of PJK in ASD patients following the second sacral alar-iliac (S2AI) fixation. Methods: A total of 163 patients with ASD who underwent surgical treatment with S2AI fixation were retrospectively reviewed. According to the median value of pelvic tilt ratio (PTr) measured at baseline, patients were divided into the high PT group (PTr ≥ 0.6) and the low PT group (PTr < 0.6). Patients were further subdivided according to the degree of PT correction with the age-adjusted equation: PT = (age – 55) / 3 +20. Patients who met the exact ± 10-year threshold for age-adjusted targets were assigned to group I (ideal correction). Patients whose correction deviated by more than 10 years above or below their age were classified into group U (undercorrection) and group O (overcorrection), respectively. Demographic, surgical, and radiographic parameters and the rates of PJK were compared between groups. Results: Patients in the high PT group had significantly lower baseline TK, LL, as well as greater PI-LL and T1PA compared with the low PT group (all P<0.05). Notably, the incidence of PJK was significantly higher in the high PT group compared to the low PT group (43.2% vs. 12.2%, c²=19.612, P<0.001). Further stratification by age-adjusted PT correction revealed significant differences in radiographic parameters across the subsets within both the low and high PT groups. In addition, among patients in the high PT group, the incidence of PJK was significantly lower in the overcorrected PT group (11/38, 28.9%) than under- (14/23, 60.9%) and ideal correction (10/20, 50%) of PT (c²=6.449, P=0.040). Conclusion: Patients in the high PT group, representing those with exhausted pelvic compensatory capacity, had a significantly higher risk of PJK compared to the low PT group. Further stratification by postoperative age-adjusted PT correction revealed that, within the high PT group, overcorrection of PT was associated with the lowest incidence of PJK, while undercorrection presented the highest risk. These findings suggest that patients with substantial baseline pelvic decompensation may benefit from a more aggressive PT correction to provide a stable foundation for spinal constructs and improve clinical outcomes in ASD surgery. adult spinal deformity pelvic compensation proximal junctional kyphosis pelvic tilt S2 alar-iliac screw Figures Figure 2 Figure 3 Figure 4 Introduction Proximal junctional kyphosis (PJK) is a frequently observed complication after long-instrumented surgery for adult spinal deformity (ASD)[ 1 – 3 ]. The prevalence of PJK after surgery has been reported to vary widely from 6–62%, and the risk is particularly higher in patients with long fusion to the pelvis with the second sacral alar-iliac (S2AI) screws [ 4 , 5 ]. Of those who develop PJK, up to 47% of patients might develop proximal junctional failure (PJF), causing more serious symptoms, including neurological deficit, and a greater likelihood for revision surgery[ 6 ]. Given the high incidence of PJK and its potentially disabling effects, the prevention of PJK is an important consideration for spinal surgeons. The amount of sagittal alignment correction has been reported to be closely associated with the development of PJK[ 7 , 8 ]. Lafage et al.[ 9 ] reported that overcorrection of the lumbar lordosis was a risk factor for PJK. Katsuura et al.[ 10 ] also found that the increased postoperative TK could elevate the risk of PJK. Despite the increased recognition and emphasis on spinal alignment correction, the role of pelvic morphology modifications is underestimated. Pelvic morphology dictates the biomechanics of the spine and represents the cornerstone of postural equilibrium. Pelvic retroversion, as quantified by pelvic tilt (PT), is a compensatory mechanism initiated against sagittal malalignment in patients with ASD [ 11 ]. If the deformity continues to progress, the pelvis compensation will ultimately reach its limits, resulting in exhausted pelvic compensation with increased PT. This typically occurs in those with severe deformities that require pelvic fixation. Despite the reported significant association between greater PT and inferior health-related quality of life [ 12 ], little is known regarding the relationship between PT and the occurrence of PJK in patients with S2AI fixation. PT is a posture-dependent parameter and is directly correlated with an individual PI[ 13 ]. Thus, a spinal surgeon is unable to assess whether a large degree of retroversion represents exhaustion of the compensatory reserve given that ASD patients often present with a large PI[ 14 ]. To overcome the inherent limitation of PT, Mac-Thiong et al.[ 15 ] put forward the concept of pelvic tilt ratio (PTr, defined as PT/PI) to reflect the true status of pelvic compensation. They reported that patients with a PTr > 0.5 may be predisposed to the progress of spinal pathology. However, Ponchelet et al.[ 16 ] found that patients with low PT had a similar incidence of PJK compared with patients with high PT. These contradictory findings questioned the role of pelvic compensation in PJK development. However, the inclusion of heterogeneous groups of patients with anterior or posterior procedures and distal fusion segments may undermine the validity of their findings. Moreover, the optimal degree of PT correction required for different pelvic compensatory statuses remains unclear in the surgical decision-making process. In this study, we further introduced the PTr to better reflect the pelvic compensatory capacity and to investigate the relationship between pelvic compensation and the development of PJK in patients with ASD following surgery. The stringent inclusion of patients with S2AI fixation allows for an unbiased analysis of the role of PTr in patients with severe sagittal deformity. Materials and Methods Subjects This study was approved by the institutional review board (IRB) of our institution. A consecutive cohort of ASD patients who had undergone corrective surgery between January 2014 and December 2020 at our institute were retrospectively reviewed. Inclusion criteria were: (1) diagnosis of ASD; (2) pelvic fixation with S2AI screws; (3) with a minimum follow-up of 2 years. Exclusion criteria were patients who were under 50 years old, with previous spinal surgical history, or with incomplete radiographic records. According to the ratio of PT to PI measured at baseline, patients were classified into two groups. The low PT group was defined as PTr < 0.6, which was the median value for the patient cohort (Fig1. a-b), while the high PT group was defined as PTr ≥ 0.6 (Fig1. c-d)[17]. Patients were further subdivided into three groups—group I (ideal correction), group U (undercorrection), and group O (overcorrection)— based on the degree of PT correction by adjusting for age. The target of PT correction was calculated using the following formula: PT= (age-55)/3+20[18, 19]. In group I, the actual postoperative PT fell within a ±10-year interval of the age-adjusted target. Patients in group U and group O were assigned targets that deviated by more than 10 years above or below their age, respectively[20]. Radiographic and clinical evaluation Standing whole-spine anteroposterior and lateral radiographs were obtained at the initial and last visit to our clinic. All the radiographic parameters were measured by an independent experienced spinal surgeon using the validated software (Surgimap, Nemaris, Inc., New York, NY). The following radiographic parameters were measured preoperatively and postoperatively: coronal Cobb angle, thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), PT, sacral slope (SS), T1 pelvic angle (T1PA), and PI minus LL (PI-LL). PJK was defined at the latest follow-up radiograph based on the Glattes definition: proximal junctional angle (PJA) greater than 10° and at least 10° greater than the corresponding preoperative measurement. The presence of both criteria was necessary to be identified as PJK[4]. Patients were also further grouped based on the presence or absence of PJK to identify the possible risk factors for PJK. Statistical analysis Statistical analysis was performed using SPSS version 22.0 (SPSS Inc., Chicago, IL). Continuous values were expressed as mean ± standard deviation and were compared using independent-sample t-test or one-way analysis of variance (ANOVA), respectively. The Chi-square test was employed to evaluate the categorical variables. A P value of <0.05 was considered statistically significant. Results Demographics data This study included a total of 163 patients with ASD, including 21 males and 142 females, with a mean age of 61.9 ± 7.0 years. The mean follow-up duration was 45.8 ± 28.6 months. Among this cohort, 81 patients were categorized into the high PT group, while 82 patients were categorized into the low PT group. The overall average PTr was 0.64 ± 0.25, with 0.73 ± 0.23 in the high PT group and 0.46 ± 0.10 in the low PT group. Three-column osteotomies were more commonly performed in the high PT group (46/81, 56.8%) compared to the low PT group (21/82, 25.6%, P = 0.001). No significant differences were observed between the groups in terms of age, gender, BMD, BMI, fusion segments, follow-up periods, and the UIV level (P > 0.05). Comparisons between the low and high PT groups As is shown in Table 2 , patients in the high PT group exhibited significantly lower baseline values for TK (11.6°±15.3° vs 20.9°±15.2°, P < 0.001), and LL (7.0°±14.6° vs 27.9°±16.7°, P 0.05). Additionally, the high PT group had significantly higher PI-LL (37.0°±17.2° vs 20.3°±18.8°, P < 0.001), and T1PA (35.1°±11.7° vs 24.6°±11.4°, P < 0.001). PI did not differ significantly between the two groups, while accordingly, SS was significantly lower in the high PT group (9.1°±8.6° vs 25.3°±7.5°, P < 0.001). Table 1 Demographic data of the low PT and high PT groups Low PT (n = 82) High PT (n = 81) P value Age (y) 61.5 ± 6.5 62.3 ± 7.6 0.464 Sex (M/F) 12/70 9/72 0.502 BMD -1.4 ± 0.8 -1.1 ± 0.6 0.126 BMI 26.7 ± 2.8 25.9 ± 3.6 0.271 Fusion segments 9.9 ± 2.8 10.6 ± 2.4 0.315 Follow-up (months) 31.3 ± 9.4 33.3 ± 7.7 0.409 UIV level T7 or above 26 22 0.524 T8 or lower 56 59 Three column osteotomy 21 (25.6%) 46 (56.8%) 0.001 PJK (n, %) 10 (12.2%) 35 (43.2%) P < 0.001 Table 2 Comparison of radiographic data between the low and high PT groups Variables Low PT (n = 82) High PT (n = 81) P value Baseline Cobb angle (°) 39.0 ± 18.3 43.7 ± 21.4 0.132 Thoracic kyphosis (°) 20.9 ± 15.2 11.6 ± 15.3 < 0.001 Lumbar lordosis (°) 27.9 ± 16.7 7.0 ± 14.6 < 0.001 Sagittal vertical axis (mm) 29.4 ± 48.1 37.4 ± 52.4 0.312 Pelvic incidence (°) 48.2 ± 13.0 46.1 ± 12.5 0.440 Pelvic tilt (°) 22.7 ± 8.4 32.9 ± 9.4 < 0.001 Sacral slope (°) 25.3 ± 7.5 9.1 ± 8.6 < 0.001 PTr 0.46 ± 0.10 0.73 ± 0.23 < 0.001 PI-LL (°) 20.3 ± 18.8 37.0 ± 17.2 < 0.001 T1 pelvic angle (°) 24.6 ± 11.4 35.1 ± 11.7 < 0.001 Postoperatively Cobb angle (°) 17.9 ± 10.3 19.7 ± 13.4 0.491 Thoracic kyphosis (°) 26.7 ± 12.4 22.6 ± 11.8 0.033 Lumbar lordosis (°) 37.9 ± 11.5 33.0 ± 11.1 0.006 Sagittal vertical axis (mm) 11.0 ± 27.1 7.3 ± 22.3 0.353 Pelvic incidence (°) 45.9 ± 13.0 41.1 ± 10.9 0.011 Pelvic tilt (°) 19.1 ± 8.5 19.1 ± 9.3 0.995 Sacral slope (°) 26.8 ± 9.4 21.8 ± 8.5 < 0.001 PTr 0.41 ± 0.15 0.45 ± 0.19 0.155 PI-LL (°) 8.1 ± 12.1 8.2 ± 12.9 0.961 T1 pelvic angle (°) 18.5 ± 8.4 17.5 ± 8.5 0.449 Postoperatively, no significant differences were found between the two groups in terms of the Cobb angle, SVA, PT, PTr, PI-LL, and T1PA (P > 0.05). However, patients in the high PT group demonstrated significantly lower TK (22.6°±11.8° vs 26.7°±12.4°, P = 0.033), LL (33.0°±11.1° vs 37.9°±11.5°, P = 0.006), PI (41.1 ± 10.9° vs 45.9°±13.0°, P = 0.011), and SS (21.8°±8.5° vs 26.8°±9.4°, P < 0.001). Among all subjects, PJK was observed in 45 (27.6%) of 163 patients, with 10 cases in the low PT group and 35 cases in the high PT group. The incidence of PJK was significantly higher in the high PT group (Fig. 3 ) compared to the low PT group (43.2% vs. 12.2%, χ²=19.612, P < 0.001). Comparison of radiographic data according to the degree of PT correction by adjusting for age. Stratifying patients by age-adjusted postoperative PT, significant differences in radiographic parameters were observed across the subsets in both the low PT (Table 3 ) and high PT group (Table 4 ). At baseline, Group U exhibited the highest PI-LL and T1PA, followed by Group I, with Group O showing the lowest values for these parameters. Regarding the pelvic parameters, Group U had the highest PI and PT as compared to the other two groups. After surgery, the trends observed at baseline were largely maintained. Group U continued to show the highest PI, PT, PI-LL, and T1PA values across all groups. These trends were consistent across both high PT and low PT groups, with Group O showing the lowest postoperative values for these parameters. No significant differences were found between groups in terms of the Cobb angle, TK, LL, and SVA at either baseline or postoperatively in both the low PT and high PT groups. Table 3 Comparison of radiographic data according to the degree of PT correction by adjusting for age in patients with low PT. Variables Group U (n = 19) Group I (n = 22) Group O (n = 41) P value Baseline Cobb angle (°) 37.3 ± 12.4 37.1 ± 20.0 40.8 ± 19.8 0.673 Thoracic kyphosis (°) 19.9 ± 13.7 18.3 ± 12.4 22.8 ± 17.2 0.516 Lumbar lordosis (°) 30.4 ± 13.8 27.4 ± 15.9 27.0 ± 18.5 0.752 Sagittal vertical axis (mm) 55.3 ± 74.0 16.2 ± 37.0 24.5 ± 32.6 0.021 Pelvic incidence (°) 58.8 ± 12.0 50.4 ± 11.9 42.1 ± 10.3 < 0.001 Pelvic tilt (°) 29.8 ± 8.6 23.9 ± 8.0 18.7 ± 6.0 < 0.001 Sacral slope (°) 28.8 ± 6.9 26.3 ± 6.8 23.1 ± 7.4 0.014 PTr 0.5 ± 0.1 0.5 ± 0.1 0.4 ± 0.1 0.188 PI-LL (°) 28.4 ± 19.3 23.0 ± 19.1 15.1 ± 17.1 0.027 T1 pelvic angle (°) 33.0 ± 11.0 24.1 ± 11.7 21.0 ± 9.5 < 0.001 Postoperatively Cobb angle (°) 13.2 ± 6.4 14.1 ± 7.9 17.3 ± 11.4 0.516 Thoracic kyphosis (°) 25.5 ± 13.9 27.4 ± 11.0 26.9 ± 12.6 0.882 Lumbar lordosis (°) 41.2 ± 9.4 33.2 ± 13.1 38.9 ± 10.9 0.060 Sagittal vertical axis (mm) 21.4 ± 26.0 6.4 ± 25.2 8.6 ± 27.9 0.151 Pelvic incidence (°) 60.1 ± 9.4 44.8 ± 12.7 40.0 ± 9.3 < 0.001 Pelvic tilt (°) 30.4 ± 4.0 22.2 ± 3.1 12.1 ± 4.5 < 0.001 Sacral slope (°) 29.5 ± 8.0 22.9 ± 11.7 27.6 ± 8.0 0.056 PTr 0.5 ± 0.1 0.5 ± 0.1 0.3 ± 0.1 < 0.001 PI-LL (°) 18.9 ± 10.2 11.6 ± 10.1 1.1 ± 9.2 < 0.001 T1 pelvic angle (°) 28.1 ± 5.0 20.2 ± 6.6 13.1 ± 5.9 < 0.001 PJK (n, %) 2 (10.5%) 2 (10.0%) 6 (14.6%) 0.789 Table 4 Comparison of radiographic data according to the degree of PT correction by adjusting for age in patients with high PT. Variables Group U (n = 23) Group I (n = 20) Group O (n = 38) P value Baseline Cobb angle (°) 41.0 ± 18.1 40.9 ± 22.5 49.5 ± 21.6 0.252 Thoracic kyphosis (°) 11.6 ± 17.1 11.7 ± 9.2 11.6 ± 17.0 1.000 Lumbar lordosis (°) 9.9 ± 17.2 2.3 ± 12.5 7.8 ± 13.7 0.209 Sagittal vertical axis (mm) 31.0 ± 54.0 36.7 ± 50.3 41.6 ± 53.4 0.750 Pelvic incidence (°) 51.3 ± 9.2 45.8 ± 13.9 38.8 ± 11.1 < 0.001 Pelvic tilt (°) 42.0 ± 8.0 36.4 ± 7.4 29.8 ± 8.1 < 0.001 Sacral slope (°) 9.2 ± 7.8 9.3 ± 10.4 8.9 ± 8.3 0.982 PTr 0.8 ± 0.1 0.9 ± 0.3 0.8 ± 0.2 0.586 PI-LL (°) 41.4 ± 19.8 43.6 ± 12.1 30.9 ± 16.1 0.009 T1 pelvic angle (°) 40.9 ± 9.9 36.8 ± 7.8 30.7 ± 12.9 0.003 Postoperatively Cobb angle (°) 12.4 ± 6.4 15.4 ± 18.3 14.1 ± 11.9 0.645 Thoracic kyphosis (°) 23.8 ± 10.9 20.3 ± 10.2 23.2 ± 13.0 0.578 Lumbar lordosis (°) 30.9 ± 8.5 30.6 ± 7.8 35.6 ± 13.4 0.150 Sagittal vertical axis (mm) 6.8 ± 22.1 5.6 ± 24.6 8.6 ± 21.7 0.880 Pelvic incidence (°) 49.2 ± 9.5 43.1 ± 8.2 35.1 ± 9.5 < 0.001 Pelvic tilt (°) 30.3 ± 4.2 21.6 ± 3.1 10.9 ± 4.5 < 0.001 Sacral slope (°) 18.5 ± 8.7 21.4 ± 7.2 24.0 ± 8.5 0.047 PTr 0.6 ± 0.1 0.5 ± 0.1 0.3 ± 0.1 < 0.001 PI-LL (°) 18.3 ± 10.7 12.8 ± 9.2 -0.4 ± 9.9 < 0.001 T1 pelvic angle (°) 26.0 ± 5.8 19.0 ± 6.1 11.5 ± 5.9 < 0.001 PJK (n, %) 14 (60.9%) 10 (50.0%) 11 (28.9%) 0.040 In the low PT group, no significant differences were noted in the PJK incidence among the groups (Table 3 ). However, the incidence of PJK differed significantly among groups in the high PT group (χ²=6.449, P = 0.040, Table 4 ). Specifically, Group U showed the highest incidence of PJK (14/23, 60.9%), followed by Group I with a rate of 50.0% (10/20). Conversely, Group O (Fig. 4 ) exhibited the lowest risk of developing PJK (11/38, 28.9%). Discussion Pelvic retroversion, as evaluated by PT, is an important compensatory mechanism in response to spinopelvic malalignment. However, there is a paucity of studies investigating the role of pelvic compensatory capacity in the setting of PJK in patients with long-segment fusion with S2AI. In the current study, we found that patients in the high PT group had a significantly higher risk of encountering PJK than the low PT group. When further stratifying patients by age-adjusted postoperative PT, no significant difference in PJK incidence was observed among the three groups with different amounts of PT correction in the low PT group. Nevertheless, in the high PT group, patients with overcorrected PT exhibited the lowest incidence of PJK compared to those with under- or ideally corrected PT. These findings offer valuable insights into sagittal malalignment patterns, prognosis, and clinical outcomes in high and low PT patients, suggesting that individualized surgical strategies may help reduce the risk of PJK after surgery. PJK remains a common mechanical complication in patients with ASD following long-segment fusion surgery and its exact cause is not fully understood[ 2 , 5 ]. Previous studies have increasingly highlighted the important role of pelvic compensation during corrective surgery[ 21 ]. However, few investigated the association between pelvic compensation and the occurrence of PJK. PT has been used widely to describe and quantify the pelvic compensation capacity[ 13 ]. Since PT is proportional to constant PI, patients with higher PI may inevitably present with higher PT[ 22 ]. Therefore, the absolute value of PT alone cannot precisely represent the real status of pelvic compensation. In an effort to better reflect the pelvic morphology of the cohorts, the PTr, namely the ratio of PT to PI, was calculated and patients were classified into the low PT and high PT group. The PTr cutoff used herein was 0.6, which was the median value of this cohort. Based on our categorization, individuals in the high PT group represented patients whose pelvic compensatory capacity had reached its limit. These patients are characterized by significantly lower TK and LL, and greater global sagittal malalignment, as indicated by PI-LL, and T1PA values. These findings were echoed by those of Lee et al.[ 14 ], who found that patients with higher PTr tended to struggle with maintaining sagittal alignment. Increasing PT represents the excessive retroversion of the pelvis. As the pelvic compensatory capacity is exhausted, compensatory mechanisms may then extend to the lower extremities and the thoracic spine, resulting in knee flexion, a flat thoracic spine, and a trunk leaning forward. This may help explain the more severe global sagittal decompensation in patients with high PT. Furthermore, we found that the incidence of PJK was significantly higher in the high PT group compared to the low PT group This was in line with Nicholls et al.’s study, which reported that higher preoperative PT was predictive for the development of PJK[ 23 ]. PT reflects pelvic compensation mechanisms, and excessive pelvic retroversion indicates a more rigid or maladaptive compensatory state, which could contribute to postoperative PJK risk independently of the degree of sagittal correction. Overall, our study suggests that patients with higher PT may be at greater risk not only due to baseline deformity but also due to potential biomechanical implications of excessive pelvic compensation. Restoration of appropriate pelvic alignment is also a key feature of ASD surgery. In the current study, we further stratified patients based on the postoperative age-adjusted PT correction. The results showed that patients with PT undercorrection exhibited the highest PI-LL and T1PA as compared to Group I and Group O. This may be due to the fact that patients in Group U had the highest baseline PI and PT, causing the inadequate correction of LL and insufficient restoration of the pelvis. These results are supported by the study of Passias et al.[ 24 ], who found that patients with pelvic nonresponse continued to have a PI − LL mismatch compared with adequate PT correction. Similar results were also reported by Dave et al. in a study investigating the factors affecting PT normalization[ 25 ]. They found that patients with normalized PT were more likely to have overcorrected PI-LL. Notably, despite no significant differences noted in the PJK incidence among the groups in the low PT group, patients in the high PT group experienced varying PJK risks depending on the degree of PT correction. Specifically, Group U showed the highest incidence of PJK (60.9%), followed by Group I (50.0%), with Group O exhibited the lowest risk of developing PJK (28.9%). Patients in the high PT group exemplify those whose pelvic compensatory mechanisms have reached their maximum capacity. For these patients, inadequate restoration of the pelvic alignment could lead to compensatory overextension of proximal mobile spinal segments and increased stress at the junctional regions, thereby raising the risk of PJK. In contrast, mild overcorrection can better accommodate with high PI values of this cohort and effectively restore LL, thereby minimizing residual strain on the spine and enhancing postoperative stability​. Therefore, the results of our study suggest that, for patients with substantial baseline pelvic decompensation, achieving adequate postoperative PT alignment may require a more aggressive surgical correction than ideal age-specific alignment targets would typically recommend. This strategy emphasizes the importance of restoring pelvic compensation to establish a stable, well-aligned foundation for long spinal-pelvic constructs, ultimately improving patient outcomes by reducing the risk of PJK. This study has a few limitations. First, as a single-center study where S2AI fixation was routinely employed for pelvic stabilization, our findings may not be generalizable to populations managed with alternative fixation techniques. Additionally, the limited sample size may have constrained the statistical power to detect subtler associations. Second, the retrospective design inherently introduces selection bias and limits our ability to comprehensively assess dynamic compensatory mechanisms, particularly in the lower extremities, as full-body radiographic imaging was not available. Third, while we accounted for pelvic compensation, multiple radiographic parameters—such as PI-LL mismatch, T1PA, and sagittal vertical axis—are simultaneously adjusted during surgery to achieve alignment goals. The complex interplay between these factors introduces potential confounders that were not fully controlled for in our analysis. Future studies should employ clustering techniques or multivariate modeling to delineate the relative contributions of different realignment strategies to PJK risk. Moreover, our study lacks patient-reported outcome measures (PROMs), which are essential to understanding the clinical impact of spinal alignment and compensatory changes. Incorporating PROMs in future studies will help contextualize radiographic findings with functional outcomes and patient quality of life. Conclusion Patients with high PT, representing those with exhausted pelvic compensatory capacity, faced a significantly higher risk of PJK compared to the low PT group. Further stratification by postoperative age-adjusted PT correction revealed that, within the high PT group, overcorrection of PT was associated with the lowest incidence of PJK, while undercorrection presented the highest risk. These findings suggest that patients with substantial baseline pelvic decompensation may benefit from a more aggressive PT correction to provide a stable foundation for spinal constructs and improve patient outcomes in ASD surgery. Declarations Ethics approval and consent to participate: This study was approved by the institutional review board (IRB) of the Nanjing Drum Tower Hospital (2021-LCYJ-DBZ-05). Consent for publication: Not applicable. Availability of data and materials: Data sharing is not applicable to this article as no datasets were generated or analysed during the current study. Competing interests: The authors declare that they have no competing interests. Funding: This work was supported by the National Natural Science Foundation of China (NSFC) (No. 82272545), and the Jiangsu Province key R & D program for Social Development (Grant No. BE2023658). Authors' contributions: Y.X,Y.Q, Z.L, and Z.Z concepted and designed the study. C.F, D.L, C.L, H.X, Z.T, B.L, X.Q, and B.S collected the data. Y.X, J.L, and Z.H analyzed and interpreted the data. Y.X, C.F and Z.Z drafted the manuscript. Y.Q, Z.L, and Z.Z critically revised the manuscript. Y.Q, and Z.L obtained the funding. 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Eur Spine J 33:599-609. doi: 10.1007/s00586-023-07966-0 Schwab FJ, Blondel B, Bess S, Hostin R, Shaffrey CI, Smith JS, Boachie-Adjei O, Burton DC, Akbarnia BA, Mundis GM, Ames CP, Kebaish K, Hart RA, Farcy JP, Lafage V (2013) Radiographical spinopelvic parameters and disability in the setting of adult spinal deformity: a prospective multicenter analysis. Spine (Phila Pa 1976) 38:E803-812. doi: 10.1097/BRS.0b013e318292b7b9 Li J, Tang Z, Hu Z, Xu Y, Liang B, Qiu Y, Zhu Z, Liu Z (2024) Sagittal Imbalance in Degenerative Kyphosis: Prevalence and Implication on Postoperative Mechanical Failure. Neurosurgery. doi: 10.1227/neu.0000000000002976 Lafage R, Schwab F, Glassman S, Bess S, Harris B, Sheer J, Hart R, Line B, Henry J, Burton D, Kim H, Klineberg E, Ames C, Lafage V (2017) Age-Adjusted Alignment Goals Have the Potential to Reduce PJK. Spine (Phila Pa 1976) 42:1275-1282. doi: 10.1097/brs.0000000000002146 Katsuura Y, Lafage R, Kim HJ, Smith JS, Line B, Shaffrey C, Burton DC, Ames CP, Mundis GM, Jr., Hostin R, Bess S, Klineberg EO, Passias PG, Lafage V (2022) Alignment Targets, Curve Proportion and Mechanical Loading: Preliminary Analysis of an Ideal Shape Toward Reducing Proximal Junctional Kyphosis. Global Spine J 12:1165-1174. doi: 10.1177/2192568220987188 Lafage V, Schwab F, Patel A, Hawkinson N, Farcy JP (2009) Pelvic tilt and truncal inclination: two key radiographic parameters in the setting of adults with spinal deformity. Spine (Phila Pa 1976) 34:E599-606. doi: 10.1097/BRS.0b013e3181aad219 Schwab F, Lafage V, Patel A, Farcy JP (2009) Sagittal plane considerations and the pelvis in the adult patient. Spine (Phila Pa 1976) 34:1828-1833. doi: 10.1097/BRS.0b013e3181a13c08 Beyer G, Khalifé M, Lafage R, Yang J, Elysee J, Frangella N, Steinmetz L, Ge D, Varlotta C, Stekas N, Manning J, Protopsaltis T, Passias P, Buckland A, Schwab F, Lafage V (2020) Pelvic Compensation in Sagittal Malalignment: How Much Retroversion Can the Pelvis Accommodate? Spine (Phila Pa 1976) 45:E203-e209. doi: 10.1097/brs.0000000000003228 Lee KY, Lee JH, Im SK (2021) Optimal Lumbar Lordosis Correction for Adult Spinal Deformity with Severe Sagittal Imbalance in Patients Over Age 60: Role of Pelvic Tilt and Pelvic Tilt Ratio. Spine (Phila Pa 1976) 46:E1246-e1253. doi: 10.1097/brs.0000000000004068 Mac-Thiong JM, Roussouly P, Berthonnaud E, Guigui P (2011) Age- and sex-related variations in sagittal sacropelvic morphology and balance in asymptomatic adults. Eur Spine J 20 Suppl 5:572-577. doi: 10.1007/s00586-011-1923-2 Ponchelet L, Khalife M, Finoco M, Duray C, Guigui P, Ferrero E (2024) Influence of pelvic tilt correction on PJK occurrence after adult spinal deformity surgery. Eur Spine J. doi: 10.1007/s00586-024-08180-2 Ferrero E, Vira S, Ames CP, Kebaish K, Obeid I, O'Brien MF, Gupta MC, Boachie-Adjei O, Smith JS, Mundis GM, Challier V, Protopsaltis TS, Schwab FJ, Lafage V (2016) Analysis of an unexplored group of sagittal deformity patients: low pelvic tilt despite positive sagittal malalignment. Eur Spine J 25:3568-3576. doi: 10.1007/s00586-015-4048-1 Lafage R, Schwab F, Challier V, Henry JK, Gum J, Smith J, Hostin R, Shaffrey C, Kim HJ, Ames C, Scheer J, Klineberg E, Bess S, Burton D, Lafage V (2016) Defining Spino-Pelvic Alignment Thresholds: Should Operative Goals in Adult Spinal Deformity Surgery Account for Age? Spine (Phila Pa 1976) 41:62-68. doi: 10.1097/brs.0000000000001171 Park SJ, Park JS, Kang DH, Lee CS (2024) Ideal Lumbar Lordosis Correction in Patients with Adult Spinal Deformity Without Adversely Impacting Pelvic Tilt and Pelvic Incidence Minus Lumbar Lordosis: A Study of 426 Cases. Spine (Phila Pa 1976). doi: 10.1097/brs.0000000000005077 Passias PG, Jalai CM, Diebo BG, Cruz DL, Poorman GW, Buckland AJ, Day LM, Horn SR, Liabaud B, Lafage R, Soroceanu A, Baker JF, McClelland S, 3rd, Oren JH, Errico TJ, Schwab FJ, Lafage V (2019) Full-Body Radiographic Analysis of Postoperative Deviations From Age-Adjusted Alignment Goals in Adult Spinal Deformity Correction and Related Compensatory Recruitment. Int J Spine Surg 13:205-214. doi: 10.14444/6028 Kwon O, Lee S, Park SM, Yeom JS, Kim HJ (2022) A Complement Type to SRS-Schwab Adult Spinal Deformity Classification: The Failure of Pelvic Compensation. Spine (Phila Pa 1976) 47:1295-1302. doi: 10.1097/brs.0000000000004404 Yilgor C, Sogunmez N, Boissiere L, Yavuz Y, Obeid I, Kleinstück F, Pérez-Grueso FJS, Acaroglu E, Haddad S, Mannion AF, Pellise F, Alanay A (2017) Global Alignment and Proportion (GAP) Score: Development and Validation of a New Method of Analyzing Spinopelvic Alignment to Predict Mechanical Complications After Adult Spinal Deformity Surgery. J Bone Joint Surg Am 99:1661-1672. doi: 10.2106/jbjs.16.01594 Nicholls FH, Bae J, Theologis AA, Eksi MS, Ames CP, Berven SH, Burch S, Tay BK, Deviren V (2017) Factors Associated With the Development of and Revision for Proximal Junctional Kyphosis in 440 Consecutive Adult Spinal Deformity Patients. Spine (Phila Pa 1976) 42:1693-1698. doi: 10.1097/brs.0000000000002209 Passias PG, Pierce KE, Williamson TK, Krol O, Lafage R, Lafage V, Schoenfeld AJ, Protopsaltis TS, Vira S, Line B, Diebo BG, Ames CP, Kim HJ, Smith JS, Chou D, Daniels AH, Gum JL, Shaffrey CI, Burton DC, Kelly MP, Klineberg EO, Hart RA, Bess S, Schwab FJ, Gupta MC (2023) Pelvic Nonresponse Following Treatment of Adult Spinal Deformity: Influence of Realignment Strategies on Occurrence. Spine (Phila Pa 1976) 48:645-652. doi: 10.1097/brs.0000000000004464 Dave P, Lafage R, Smith JS, Line BG, Tretiakov PS, Mir J, Diebo B, Daniels AH, Gum JL, Hamilton DK, Buell T, Than KD, Fu KM, Scheer JK, Eastlack R, Mullin JP, Mundis G, Hosogane N, Yagi M, Nunley P, Chou D, Mummaneni PV, Klineberg EO, Kebaish KM, Lewis S, Hostin RA, Gupta MC, Kim HJ, Ames CP, Hart RA, Lenke LG, Shaffrey CI, Bess S, Schwab FJ, Lafage V, Burton DC, Passias PG (2024) Predictors of pelvic tilt normalization: a multicenter study on the impact of regional and lower-extremity compensation on pelvic alignment after complex adult spinal deformity surgery. J Neurosurg Spine 40:505-512. doi: 10.3171/2023.11.Spine23766 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 18 Jul, 2025 Read the published version in Journal of Orthopaedic Surgery and Research → Version 1 posted Editorial decision: Revision requested 08 Jun, 2025 Reviews received at journal 07 Jun, 2025 Reviewers agreed at journal 23 May, 2025 Reviews received at journal 14 Apr, 2025 Reviewers agreed at journal 06 Apr, 2025 Reviewers agreed at journal 06 Apr, 2025 Reviewers invited by journal 03 Apr, 2025 Editor assigned by journal 03 Apr, 2025 Submission checks completed at journal 03 Apr, 2025 First submitted to journal 02 Apr, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6361426","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":442725455,"identity":"01d1472d-ba22-4f5d-a072-1edbfa0bcdf6","order_by":0,"name":"Yanjie Xu","email":"","orcid":"","institution":"Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Yanjie","middleName":"","lastName":"Xu","suffix":""},{"id":442725456,"identity":"d72f6b0a-6d6b-41e7-bd51-6c408a959cae","order_by":1,"name":"Changsheng Fan","email":"","orcid":"","institution":"Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Changsheng","middleName":"","lastName":"Fan","suffix":""},{"id":442725457,"identity":"4841567c-8328-446f-9827-fe14e642045d","order_by":2,"name":"Dongyue Li","email":"","orcid":"","institution":"Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Dongyue","middleName":"","lastName":"Li","suffix":""},{"id":442725458,"identity":"19a79e2a-1d3b-4133-a396-0a77df11d39a","order_by":3,"name":"Jie Li","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"Li","suffix":""},{"id":442725459,"identity":"558955df-a677-4e89-a24f-9f11585a733c","order_by":4,"name":"Chen Ling","email":"","orcid":"","institution":"Jiangsu University","correspondingAuthor":false,"prefix":"","firstName":"Chen","middleName":"","lastName":"Ling","suffix":""},{"id":442725460,"identity":"91498ba2-be0d-4c83-a925-ec172f1ea033","order_by":5,"name":"Hui Xu","email":"","orcid":"","institution":"Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Hui","middleName":"","lastName":"Xu","suffix":""},{"id":442725461,"identity":"0bdc1176-a743-4825-a9bb-bc4bef34ffc5","order_by":6,"name":"Zhen Tian","email":"","orcid":"","institution":"Nanjing University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Zhen","middleName":"","lastName":"Tian","suffix":""},{"id":442725462,"identity":"a6ed749a-2a65-4709-8d7e-9c645d8e13d0","order_by":7,"name":"Bangheng Liang","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Bangheng","middleName":"","lastName":"Liang","suffix":""},{"id":442725463,"identity":"a946d1e3-4d74-4d8d-b897-efc40864dcde","order_by":8,"name":"Zongshan Hu","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Zongshan","middleName":"","lastName":"Hu","suffix":""},{"id":442725464,"identity":"4838fc38-919a-4a17-928f-c9fc31d2f528","order_by":9,"name":"Xiaodong Qin","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaodong","middleName":"","lastName":"Qin","suffix":""},{"id":442725465,"identity":"93ae76f1-a835-4995-a0be-b15da826afb5","order_by":10,"name":"benlong Shi","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"benlong","middleName":"","lastName":"Shi","suffix":""},{"id":442725466,"identity":"a9e9d944-71c2-444e-88a2-20b968cb8c8b","order_by":11,"name":"Yong Qiu","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yong","middleName":"","lastName":"Qiu","suffix":""},{"id":442725467,"identity":"a21cc7e2-d0d9-401e-a143-226aa1a20567","order_by":12,"name":"Zhen Liu","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":false,"prefix":"","firstName":"Zhen","middleName":"","lastName":"Liu","suffix":""},{"id":442725468,"identity":"226b90fe-9f2f-4ebc-8093-af28c7a3857f","order_by":13,"name":"Zezhang Zhu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIiWNgGAWjYDACCTB5AIiZDxz4UEGaFrbEgzPOkKaFx/gwbwsROuRn9xh/+PDnjrw5/5oPB3gbGOT5xQ7g18I454yB4QyeZ4Y7Z7zdcEByB4PhzNkJ+LUwS+QYJPNIHGbccOPshgOGZxgSDG4T0MIG1HL4j8Fh+w03zjw4kNhGhBYeiRzDZoaEw4kbzvcwHDhIjBYJibRixp4Dh5M33GAzONhwRoKwX+RnJG/+8OPPYdsN5w8//vynwkaeX5qAFiT7wColiFUOAvwHSFE9CkbBKBgFIwkAAKKHTwkgxQsBAAAAAElFTkSuQmCC","orcid":"","institution":"Nanjing Drum Tower Hospital","correspondingAuthor":true,"prefix":"","firstName":"Zezhang","middleName":"","lastName":"Zhu","suffix":""}],"badges":[],"createdAt":"2025-04-02 12:53:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6361426/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6361426/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13018-025-06103-5","type":"published","date":"2025-07-18T16:05:34+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":82131181,"identity":"f02d73b6-bad7-4b3c-a472-7ecf189e33a0","added_by":"auto","created_at":"2025-05-07 05:34:25","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":267693,"visible":true,"origin":"","legend":"\u003cp\u003eRadiographs of a 51-year-old woman presenting with adult spinal deformity. The preoperative PT was 19°, PI was 49°, and PTr was 0.38. This case was classified into the low PT group (a-b). The posterior spinal fusion with T10-S2 fixation was performed. Postoperative radiographs showed a satisfactory correction of the coronal and sagittal alignment (c-d). At the 2-year follow-up, the correction was maintained well and no junctional complications were observed (e-f).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6361426/v1/dab94bb73f48f996a85d54f0.png"},{"id":82131186,"identity":"5082e0ab-fdfd-40ad-b010-725846ad1db6","added_by":"auto","created_at":"2025-05-07 05:34:25","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":231603,"visible":true,"origin":"","legend":"\u003cp\u003eRadiographs of a 67-year-old woman presenting with adult spinal deformity. The preoperative PT was 39°, PI was 30°, and PTr was 1.30. This case was classified into the high PT group (a-b). The posterior spinal fusion with T7-S2 fixation was performed. Postoperative radiographs showed a satisfactory correction of the coronal and sagittal alignment. (c-d). However, PJK was observed at the 4-year follow-up (e-f).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6361426/v1/e917cad584f56ac1db88f4d1.png"},{"id":82131185,"identity":"9c8fdeaa-4ca6-4cad-91ee-367b95060566","added_by":"auto","created_at":"2025-05-07 05:34:25","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":258967,"visible":true,"origin":"","legend":"\u003cp\u003eRadiographs of a 67-year-old woman presenting with adult spinal deformity. The preoperative PT was 45°, PI was 60°, and PTr was 0.75. This case was classified into the high PT group (a-b). The posterior spinal fusion with T9-S2 fixation was performed. The predicted age-adjusted PT was 24°. After surgery, the postoperative PT was 12°, defined as PT overcorrection (c-d). At the 3-year follow-up, the correction was maintained well and no junctional complications were observed (e-f).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6361426/v1/d25ef3e6af5597bc1ae7c21a.png"},{"id":88506158,"identity":"cc931598-5ce7-4b3c-8875-9841842d0e1d","added_by":"auto","created_at":"2025-08-07 07:31:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1880813,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6361426/v1/215d0b87-eab1-4d49-9a23-b7662d267ecc.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of Pelvic Compensation Capacity on Proximal Junctional Kyphosis: A Stratified Analysis of Pelvic Tilt in Adult Spinal Deformity Surgery","fulltext":[{"header":"Introduction","content":"\u003cp\u003eProximal junctional kyphosis (PJK) is a frequently observed complication after long-instrumented surgery for adult spinal deformity (ASD)[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The prevalence of PJK after surgery has been reported to vary widely from 6\u0026ndash;62%, and the risk is particularly higher in patients with long fusion to the pelvis with the second sacral alar-iliac (S2AI) screws [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Of those who develop PJK, up to 47% of patients might develop proximal junctional failure (PJF), causing more serious symptoms, including neurological deficit, and a greater likelihood for revision surgery[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Given the high incidence of PJK and its potentially disabling effects, the prevention of PJK is an important consideration for spinal surgeons.\u003c/p\u003e \u003cp\u003eThe amount of sagittal alignment correction has been reported to be closely associated with the development of PJK[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Lafage et al.[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] reported that overcorrection of the lumbar lordosis was a risk factor for PJK. Katsuura et al.[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] also found that the increased postoperative TK could elevate the risk of PJK. Despite the increased recognition and emphasis on spinal alignment correction, the role of pelvic morphology modifications is underestimated. Pelvic morphology dictates the biomechanics of the spine and represents the cornerstone of postural equilibrium. Pelvic retroversion, as quantified by pelvic tilt (PT), is a compensatory mechanism initiated against sagittal malalignment in patients with ASD [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. If the deformity continues to progress, the pelvis compensation will ultimately reach its limits, resulting in exhausted pelvic compensation with increased PT. This typically occurs in those with severe deformities that require pelvic fixation. Despite the reported significant association between greater PT and inferior health-related quality of life [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], little is known regarding the relationship between PT and the occurrence of PJK in patients with S2AI fixation.\u003c/p\u003e \u003cp\u003ePT is a posture-dependent parameter and is directly correlated with an individual PI[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Thus, a spinal surgeon is unable to assess whether a large degree of retroversion represents exhaustion of the compensatory reserve given that ASD patients often present with a large PI[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. To overcome the inherent limitation of PT, Mac-Thiong et al.[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] put forward the concept of pelvic tilt ratio (PTr, defined as PT/PI) to reflect the true status of pelvic compensation. They reported that patients with a PTr\u0026thinsp;\u0026gt;\u0026thinsp;0.5 may be predisposed to the progress of spinal pathology. However, Ponchelet et al.[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] found that patients with low PT had a similar incidence of PJK compared with patients with high PT. These contradictory findings questioned the role of pelvic compensation in PJK development. However, the inclusion of heterogeneous groups of patients with anterior or posterior procedures and distal fusion segments may undermine the validity of their findings. Moreover, the optimal degree of PT correction required for different pelvic compensatory statuses remains unclear in the surgical decision-making process.\u003c/p\u003e \u003cp\u003eIn this study, we further introduced the PTr to better reflect the pelvic compensatory capacity and to investigate the relationship between pelvic compensation and the development of PJK in patients with ASD following surgery. The stringent inclusion of patients with S2AI fixation allows for an unbiased analysis of the role of PTr in patients with severe sagittal deformity.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e\u003cstrong\u003eSubjects\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the institutional review board (IRB) of our institution. A consecutive cohort of ASD patients who had undergone corrective surgery between January 2014 and December 2020 at our institute were retrospectively reviewed. Inclusion criteria were: (1) diagnosis of ASD; (2) pelvic fixation with S2AI screws; (3) with a minimum follow-up of 2 years. Exclusion criteria were patients who were under 50 years old, with previous spinal surgical history, or with incomplete radiographic records.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAccording to the ratio of PT to PI measured at baseline, patients were classified into two groups. The low PT group was defined as PTr \u0026lt; 0.6, which was the median value for the patient cohort (Fig1. a-b), while the high PT group was defined as PTr \u0026ge; 0.6 (Fig1. c-d)[17].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePatients were further subdivided into three groups\u0026mdash;group I (ideal correction), group U (undercorrection), and group O (overcorrection)\u0026mdash; based on the degree of PT correction by adjusting for age. The target of PT correction was calculated using the following formula: PT= (age-55)/3+20[18, 19]. In group I, the actual postoperative PT fell within a \u0026plusmn;10-year interval of the age-adjusted target. Patients in group U and group O were assigned targets that deviated by more than 10 years above or below their age, respectively[20].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRadiographic and clinical evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStanding whole-spine anteroposterior and lateral radiographs were obtained at the initial and last visit to our clinic. All the radiographic parameters were measured by an independent experienced spinal surgeon using the validated software (Surgimap, Nemaris, Inc., New York, NY). The following radiographic parameters were measured preoperatively and postoperatively: coronal Cobb angle, thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), PT, sacral slope (SS), T1 pelvic angle (T1PA), and PI minus LL (PI-LL).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePJK was defined at the latest follow-up radiograph based on the Glattes definition: proximal junctional angle (PJA) greater than 10\u0026deg; and at least 10\u0026deg; greater than the corresponding preoperative measurement. The presence of both criteria was necessary to be identified as PJK[4]. Patients were also further grouped based on the presence or absence of PJK to identify the possible risk factors for PJK.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analysis was performed using SPSS version 22.0 (SPSS Inc., Chicago, IL). Continuous values were expressed as mean \u0026plusmn; standard deviation and were compared using independent-sample t-test or one-way analysis of variance (ANOVA), respectively. The Chi-square test was employed to evaluate the categorical variables. A P value of \u0026lt;0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eDemographics data\u003c/h2\u003e \u003cp\u003eThis study included a total of 163 patients with ASD, including 21 males and 142 females, with a mean age of 61.9\u0026thinsp;\u0026plusmn;\u0026thinsp;7.0 years. The mean follow-up duration was 45.8\u0026thinsp;\u0026plusmn;\u0026thinsp;28.6 months. Among this cohort, 81 patients were categorized into the high PT group, while 82 patients were categorized into the low PT group. The overall average PTr was 0.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25, with 0.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23 in the high PT group and 0.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10 in the low PT group. Three-column osteotomies were more commonly performed in the high PT group (46/81, 56.8%) compared to the low PT group (21/82, 25.6%, P\u0026thinsp;=\u0026thinsp;0.001). No significant differences were observed between the groups in terms of age, gender, BMD, BMI, fusion segments, follow-up periods, and the UIV level (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eComparisons between the low and high PT groups\u003c/h2\u003e \u003cp\u003eAs is shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, patients in the high PT group exhibited significantly lower baseline values for TK (11.6\u0026deg;\u0026plusmn;15.3\u0026deg; vs 20.9\u0026deg;\u0026plusmn;15.2\u0026deg;, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and LL (7.0\u0026deg;\u0026plusmn;14.6\u0026deg; vs 27.9\u0026deg;\u0026plusmn;16.7\u0026deg;, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) compared to the low PT group, while Cobb angle and SVA were similar between groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Additionally, the high PT group had significantly higher PI-LL (37.0\u0026deg;\u0026plusmn;17.2\u0026deg; vs 20.3\u0026deg;\u0026plusmn;18.8\u0026deg;, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and T1PA (35.1\u0026deg;\u0026plusmn;11.7\u0026deg; vs 24.6\u0026deg;\u0026plusmn;11.4\u0026deg;, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001). PI did not differ significantly between the two groups, while accordingly, SS was significantly lower in the high PT group (9.1\u0026deg;\u0026plusmn;8.6\u0026deg; vs 25.3\u0026deg;\u0026plusmn;7.5\u0026deg;, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\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\u003eDemographic data of the low PT and high PT groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLow PT (n\u0026thinsp;=\u0026thinsp;82)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHigh PT (n\u0026thinsp;=\u0026thinsp;81)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (y)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e61.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e62.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.464\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex (M/F)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12/70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9/72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.502\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.126\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.271\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFusion segments\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.315\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFollow-up (months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31.3\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.409\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUIV level\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT7 or above\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.524\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT8 or lower\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThree column osteotomy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21 (25.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46 (56.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePJK (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (12.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35 (43.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\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 radiographic data between the low and high PT groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLow PT (n\u0026thinsp;=\u0026thinsp;82)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHigh PT (n\u0026thinsp;=\u0026thinsp;81)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCobb angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e39.0\u0026thinsp;\u0026plusmn;\u0026thinsp;18.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e43.7\u0026thinsp;\u0026plusmn;\u0026thinsp;21.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.132\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThoracic kyphosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e20.9\u0026thinsp;\u0026plusmn;\u0026thinsp;15.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e11.6\u0026thinsp;\u0026plusmn;\u0026thinsp;15.3\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLumbar lordosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e27.9\u0026thinsp;\u0026plusmn;\u0026thinsp;16.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e7.0\u0026thinsp;\u0026plusmn;\u0026thinsp;14.6\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSagittal vertical axis (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e29.4\u0026thinsp;\u0026plusmn;\u0026thinsp;48.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e37.4\u0026thinsp;\u0026plusmn;\u0026thinsp;52.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.312\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic incidence (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e48.2\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e46.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.440\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic tilt (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e22.7\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e32.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSacral slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e25.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e9.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePTr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePI-LL (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e20.3\u0026thinsp;\u0026plusmn;\u0026thinsp;18.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e37.0\u0026thinsp;\u0026plusmn;\u0026thinsp;17.2\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT1 pelvic angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e24.6\u0026thinsp;\u0026plusmn;\u0026thinsp;11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e35.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.7\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostoperatively\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCobb angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e17.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e19.7\u0026thinsp;\u0026plusmn;\u0026thinsp;13.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.491\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThoracic kyphosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e26.7\u0026thinsp;\u0026plusmn;\u0026thinsp;12.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e22.6\u0026thinsp;\u0026plusmn;\u0026thinsp;11.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.033\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLumbar lordosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e37.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e33.0\u0026thinsp;\u0026plusmn;\u0026thinsp;11.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSagittal vertical axis (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e11.0\u0026thinsp;\u0026plusmn;\u0026thinsp;27.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e7.3\u0026thinsp;\u0026plusmn;\u0026thinsp;22.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.353\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic incidence (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e45.9\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e41.1\u0026thinsp;\u0026plusmn;\u0026thinsp;10.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.011\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic tilt (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e19.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e19.1\u0026thinsp;\u0026plusmn;\u0026thinsp;9.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.995\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSacral slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e26.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e21.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePTr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.155\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePI-LL (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.2\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.961\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT1 pelvic angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e18.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e17.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.449\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ePostoperatively, no significant differences were found between the two groups in terms of the Cobb angle, SVA, PT, PTr, PI-LL, and T1PA (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, patients in the high PT group demonstrated significantly lower TK (22.6\u0026deg;\u0026plusmn;11.8\u0026deg; vs 26.7\u0026deg;\u0026plusmn;12.4\u0026deg;, P\u0026thinsp;=\u0026thinsp;0.033), LL (33.0\u0026deg;\u0026plusmn;11.1\u0026deg; vs 37.9\u0026deg;\u0026plusmn;11.5\u0026deg;, P\u0026thinsp;=\u0026thinsp;0.006), PI (41.1\u0026thinsp;\u0026plusmn;\u0026thinsp;10.9\u0026deg; vs 45.9\u0026deg;\u0026plusmn;13.0\u0026deg;, P\u0026thinsp;=\u0026thinsp;0.011), and SS (21.8\u0026deg;\u0026plusmn;8.5\u0026deg; vs 26.8\u0026deg;\u0026plusmn;9.4\u0026deg;, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003eAmong all subjects, PJK was observed in 45 (27.6%) of 163 patients, with 10 cases in the low PT group and 35 cases in the high PT group. The incidence of PJK was significantly higher in the high PT group (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) compared to the low PT group (43.2% vs. 12.2%, χ\u0026sup2;=19.612, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eComparison of radiographic data according to the degree of PT correction by adjusting for age.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eStratifying patients by age-adjusted postoperative PT, significant differences in radiographic parameters were observed across the subsets in both the low PT (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) and high PT group (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). At baseline, Group U exhibited the highest PI-LL and T1PA, followed by Group I, with Group O showing the lowest values for these parameters. Regarding the pelvic parameters, Group U had the highest PI and PT as compared to the other two groups. After surgery, the trends observed at baseline were largely maintained. Group U continued to show the highest PI, PT, PI-LL, and T1PA values across all groups. These trends were consistent across both high PT and low PT groups, with Group O showing the lowest postoperative values for these parameters. No significant differences were found between groups in terms of the Cobb angle, TK, LL, and SVA at either baseline or postoperatively in both the low PT and high PT groups.\u003c/p\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 radiographic data according to the degree of PT correction by adjusting for age in patients with low PT.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGroup U (n\u0026thinsp;=\u0026thinsp;19)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGroup I\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;22)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGroup O (n\u0026thinsp;=\u0026thinsp;41)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCobb angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.1\u0026thinsp;\u0026plusmn;\u0026thinsp;20.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e40.8\u0026thinsp;\u0026plusmn;\u0026thinsp;19.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.673\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThoracic kyphosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.9\u0026thinsp;\u0026plusmn;\u0026thinsp;13.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22.8\u0026thinsp;\u0026plusmn;\u0026thinsp;17.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.516\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLumbar lordosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30.4\u0026thinsp;\u0026plusmn;\u0026thinsp;13.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27.4\u0026thinsp;\u0026plusmn;\u0026thinsp;15.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27.0\u0026thinsp;\u0026plusmn;\u0026thinsp;18.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.752\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSagittal vertical axis (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55.3\u0026thinsp;\u0026plusmn;\u0026thinsp;74.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.2\u0026thinsp;\u0026plusmn;\u0026thinsp;37.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24.5\u0026thinsp;\u0026plusmn;\u0026thinsp;32.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.021\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic incidence (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58.8\u0026thinsp;\u0026plusmn;\u0026thinsp;12.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50.4\u0026thinsp;\u0026plusmn;\u0026thinsp;11.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e42.1\u0026thinsp;\u0026plusmn;\u0026thinsp;10.3\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic tilt (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e18.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSacral slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28.8\u0026thinsp;\u0026plusmn;\u0026thinsp;6.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.3\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.014\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePTr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.188\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePI-LL (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28.4\u0026thinsp;\u0026plusmn;\u0026thinsp;19.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.0\u0026thinsp;\u0026plusmn;\u0026thinsp;19.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15.1\u0026thinsp;\u0026plusmn;\u0026thinsp;17.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.027\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT1 pelvic angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33.0\u0026thinsp;\u0026plusmn;\u0026thinsp;11.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21.0\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostoperatively\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCobb angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17.3\u0026thinsp;\u0026plusmn;\u0026thinsp;11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.516\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThoracic kyphosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27.4\u0026thinsp;\u0026plusmn;\u0026thinsp;11.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26.9\u0026thinsp;\u0026plusmn;\u0026thinsp;12.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.882\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLumbar lordosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41.2\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.2\u0026thinsp;\u0026plusmn;\u0026thinsp;13.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.060\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSagittal vertical axis (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21.4\u0026thinsp;\u0026plusmn;\u0026thinsp;26.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.4\u0026thinsp;\u0026plusmn;\u0026thinsp;25.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.6\u0026thinsp;\u0026plusmn;\u0026thinsp;27.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.151\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic incidence (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60.1\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44.8\u0026thinsp;\u0026plusmn;\u0026thinsp;12.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e40.0\u0026thinsp;\u0026plusmn;\u0026thinsp;9.3\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic tilt (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12.1\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSacral slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27.6\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.056\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePTr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePI-LL (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.6\u0026thinsp;\u0026plusmn;\u0026thinsp;10.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;9.2\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT1 pelvic angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28.1\u0026thinsp;\u0026plusmn;\u0026thinsp;5.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13.1\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePJK (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (10.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (10.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6 (14.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.789\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of radiographic data according to the degree of PT correction by adjusting for age in patients with high PT.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGroup U (n\u0026thinsp;=\u0026thinsp;23)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGroup I\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eGroup O (n\u0026thinsp;=\u0026thinsp;38)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCobb angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41.0\u0026thinsp;\u0026plusmn;\u0026thinsp;18.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40.9\u0026thinsp;\u0026plusmn;\u0026thinsp;22.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e49.5\u0026thinsp;\u0026plusmn;\u0026thinsp;21.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.252\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThoracic kyphosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.6\u0026thinsp;\u0026plusmn;\u0026thinsp;17.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.7\u0026thinsp;\u0026plusmn;\u0026thinsp;9.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.6\u0026thinsp;\u0026plusmn;\u0026thinsp;17.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLumbar lordosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.9\u0026thinsp;\u0026plusmn;\u0026thinsp;17.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.8\u0026thinsp;\u0026plusmn;\u0026thinsp;13.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.209\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSagittal vertical axis (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31.0\u0026thinsp;\u0026plusmn;\u0026thinsp;54.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36.7\u0026thinsp;\u0026plusmn;\u0026thinsp;50.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e41.6\u0026thinsp;\u0026plusmn;\u0026thinsp;53.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.750\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic incidence (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e51.3\u0026thinsp;\u0026plusmn;\u0026thinsp;9.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.8\u0026thinsp;\u0026plusmn;\u0026thinsp;13.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38.8\u0026thinsp;\u0026plusmn;\u0026thinsp;11.1\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic tilt (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.1\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSacral slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9.2\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.3\u0026thinsp;\u0026plusmn;\u0026thinsp;10.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.982\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePTr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.586\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePI-LL (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41.4\u0026thinsp;\u0026plusmn;\u0026thinsp;19.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e43.6\u0026thinsp;\u0026plusmn;\u0026thinsp;12.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.9\u0026thinsp;\u0026plusmn;\u0026thinsp;16.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT1 pelvic angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.7\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostoperatively\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCobb angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.4\u0026thinsp;\u0026plusmn;\u0026thinsp;18.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.645\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThoracic kyphosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.8\u0026thinsp;\u0026plusmn;\u0026thinsp;10.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20.3\u0026thinsp;\u0026plusmn;\u0026thinsp;10.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.2\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.578\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLumbar lordosis (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e35.6\u0026thinsp;\u0026plusmn;\u0026thinsp;13.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.150\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSagittal vertical axis (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.8\u0026thinsp;\u0026plusmn;\u0026thinsp;22.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;24.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.6\u0026thinsp;\u0026plusmn;\u0026thinsp;21.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.880\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic incidence (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e49.2\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e43.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e35.1\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePelvic tilt (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSacral slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.047\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePTr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePI-LL (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18.3\u0026thinsp;\u0026plusmn;\u0026thinsp;10.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.4\u0026thinsp;\u0026plusmn;\u0026thinsp;9.9\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT1 pelvic angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.0\u0026thinsp;\u0026plusmn;\u0026thinsp;5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19.0\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\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 \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePJK (n, %)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (60.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10 (50.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11 (28.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.040\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn the low PT group, no significant differences were noted in the PJK incidence among the groups (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). However, the incidence of PJK differed significantly among groups in the high PT group (χ\u0026sup2;=6.449, P\u0026thinsp;=\u0026thinsp;0.040, Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Specifically, Group U showed the highest incidence of PJK (14/23, 60.9%), followed by Group I with a rate of 50.0% (10/20). Conversely, Group O (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) exhibited the lowest risk of developing PJK (11/38, 28.9%).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003ePelvic retroversion, as evaluated by PT, is an important compensatory mechanism in response to spinopelvic malalignment. However, there is a paucity of studies investigating the role of pelvic compensatory capacity in the setting of PJK in patients with long-segment fusion with S2AI. In the current study, we found that patients in the high PT group had a significantly higher risk of encountering PJK than the low PT group. When further stratifying patients by age-adjusted postoperative PT, no significant difference in PJK incidence was observed among the three groups with different amounts of PT correction in the low PT group. Nevertheless, in the high PT group, patients with overcorrected PT exhibited the lowest incidence of PJK compared to those with under- or ideally corrected PT. These findings offer valuable insights into sagittal malalignment patterns, prognosis, and clinical outcomes in high and low PT patients, suggesting that individualized surgical strategies may help reduce the risk of PJK after surgery.\u003c/p\u003e \u003cp\u003ePJK remains a common mechanical complication in patients with ASD following long-segment fusion surgery and its exact cause is not fully understood[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Previous studies have increasingly highlighted the important role of pelvic compensation during corrective surgery[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. However, few investigated the association between pelvic compensation and the occurrence of PJK. PT has been used widely to describe and quantify the pelvic compensation capacity[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Since PT is proportional to constant PI, patients with higher PI may inevitably present with higher PT[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Therefore, the absolute value of PT alone cannot precisely represent the real status of pelvic compensation.\u003c/p\u003e \u003cp\u003eIn an effort to better reflect the pelvic morphology of the cohorts, the PTr, namely the ratio of PT to PI, was calculated and patients were classified into the low PT and high PT group. The PTr cutoff used herein was 0.6, which was the median value of this cohort. Based on our categorization, individuals in the high PT group represented patients whose pelvic compensatory capacity had reached its limit. These patients are characterized by significantly lower TK and LL, and greater global sagittal malalignment, as indicated by PI-LL, and T1PA values. These findings were echoed by those of Lee et al.[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], who found that patients with higher PTr tended to struggle with maintaining sagittal alignment. Increasing PT represents the excessive retroversion of the pelvis. As the pelvic compensatory capacity is exhausted, compensatory mechanisms may then extend to the lower extremities and the thoracic spine, resulting in knee flexion, a flat thoracic spine, and a trunk leaning forward. This may help explain the more severe global sagittal decompensation in patients with high PT. Furthermore, we found that the incidence of PJK was significantly higher in the high PT group compared to the low PT group This was in line with Nicholls et al.\u0026rsquo;s study, which reported that higher preoperative PT was predictive for the development of PJK[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. PT reflects pelvic compensation mechanisms, and excessive pelvic retroversion indicates a more rigid or maladaptive compensatory state, which could contribute to postoperative PJK risk independently of the degree of sagittal correction. Overall, our study suggests that patients with higher PT may be at greater risk not only due to baseline deformity but also due to potential biomechanical implications of excessive pelvic compensation.\u003c/p\u003e \u003cp\u003eRestoration of appropriate pelvic alignment is also a key feature of ASD surgery. In the current study, we further stratified patients based on the postoperative age-adjusted PT correction. The results showed that patients with PT undercorrection exhibited the highest PI-LL and T1PA as compared to Group I and Group O. This may be due to the fact that patients in Group U had the highest baseline PI and PT, causing the inadequate correction of LL and insufficient restoration of the pelvis. These results are supported by the study of Passias et al.[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], who found that patients with pelvic nonresponse continued to have a PI\u0026thinsp;\u0026minus;\u0026thinsp;LL mismatch compared with adequate PT correction. Similar results were also reported by Dave et al. in a study investigating the factors affecting PT normalization[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. They found that patients with normalized PT were more likely to have overcorrected PI-LL. Notably, despite no significant differences noted in the PJK incidence among the groups in the low PT group, patients in the high PT group experienced varying PJK risks depending on the degree of PT correction. Specifically, Group U showed the highest incidence of PJK (60.9%), followed by Group I (50.0%), with Group O exhibited the lowest risk of developing PJK (28.9%). Patients in the high PT group exemplify those whose pelvic compensatory mechanisms have reached their maximum capacity. For these patients, inadequate restoration of the pelvic alignment could lead to compensatory overextension of proximal mobile spinal segments and increased stress at the junctional regions, thereby raising the risk of PJK. In contrast, mild overcorrection can better accommodate with high PI values of this cohort and effectively restore LL, thereby minimizing residual strain on the spine and enhancing postoperative stability​. Therefore, the results of our study suggest that, for patients with substantial baseline pelvic decompensation, achieving adequate postoperative PT alignment may require a more aggressive surgical correction than ideal age-specific alignment targets would typically recommend. This strategy emphasizes the importance of restoring pelvic compensation to establish a stable, well-aligned foundation for long spinal-pelvic constructs, ultimately improving patient outcomes by reducing the risk of PJK.\u003c/p\u003e \u003cp\u003eThis study has a few limitations. First, as a single-center study where S2AI fixation was routinely employed for pelvic stabilization, our findings may not be generalizable to populations managed with alternative fixation techniques. Additionally, the limited sample size may have constrained the statistical power to detect subtler associations. Second, the retrospective design inherently introduces selection bias and limits our ability to comprehensively assess dynamic compensatory mechanisms, particularly in the lower extremities, as full-body radiographic imaging was not available. Third, while we accounted for pelvic compensation, multiple radiographic parameters\u0026mdash;such as PI-LL mismatch, T1PA, and sagittal vertical axis\u0026mdash;are simultaneously adjusted during surgery to achieve alignment goals. The complex interplay between these factors introduces potential confounders that were not fully controlled for in our analysis. Future studies should employ clustering techniques or multivariate modeling to delineate the relative contributions of different realignment strategies to PJK risk. Moreover, our study lacks patient-reported outcome measures (PROMs), which are essential to understanding the clinical impact of spinal alignment and compensatory changes. Incorporating PROMs in future studies will help contextualize radiographic findings with functional outcomes and patient quality of life.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003ePatients with high PT, representing those with exhausted pelvic compensatory capacity, faced a significantly higher risk of PJK compared to the low PT group. Further stratification by postoperative age-adjusted PT correction revealed that, within the high PT group, overcorrection of PT was associated with the lowest incidence of PJK, while undercorrection presented the highest risk. These findings suggest that patients with substantial baseline pelvic decompensation may benefit from a more aggressive PT correction to provide a stable foundation for spinal constructs and improve patient outcomes in ASD surgery.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u0026nbsp;\u003c/strong\u003eThis study was approved by the institutional review board (IRB) of the Nanjing Drum Tower Hospital (2021-LCYJ-DBZ-05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u0026nbsp;\u003c/strong\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u003c/strong\u003e Data sharing is not applicable to this article as no datasets were generated or analysed during the current study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eThis work was supported by the National Natural Science Foundation of China (NSFC) (No. 82272545), and the Jiangsu Province key R \u0026amp; D program for Social Development (Grant No. BE2023658).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eY.X,Y.Q, Z.L, and Z.Z concepted and designed the study.\u003c/p\u003e\n\u003cp\u003eC.F, D.L, C.L, H.X, Z.T, B.L, X.Q, and B.S collected the data.\u003c/p\u003e\n\u003cp\u003eY.X, J.L, and Z.H analyzed and interpreted the data.\u003c/p\u003e\n\u003cp\u003eY.X, \u0026nbsp;C.F and Z.Z drafted the manuscript.\u003c/p\u003e\n\u003cp\u003eY.Q, Z.L, and Z.Z critically revised the manuscript.\u003c/p\u003e\n\u003cp\u003eY.Q, and Z.L obtained the funding.\u003c/p\u003e\n\u003cp\u003eAll authors reviewed the manuscript and approved the version to be published.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgment:\u003c/strong\u003e Not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eDoodkorte RJP, Vercoulen TFG, Roth AK, de Bie RA, Willems PC (2021) Instrumentation techniques to prevent proximal junctional kyphosis and proximal junctional failure in adult spinal deformity correction-a systematic review of biomechanical studies. Spine J 21:842-854. doi: 10.1016/j.spinee.2021.01.011\u003c/li\u003e\n\u003cli\u003eLee BJ, Bae SS, Choi HY, Park JH, Hyun SJ, Jo DJ, Cho Y (2023) Proximal Junctional Kyphosis or Failure After Adult Spinal Deformity Surgery - Review of Risk Factors and Its Prevention. Neurospine 20:863-875. doi: 10.14245/ns.2346476.238\u003c/li\u003e\n\u003cli\u003eKuo CC, Soliman MAR, Aguirre AO, Ruggiero N, Kruk M, Khan A, Ghannam MM, Almeida ND, Jowdy PK, Smolar DE, Pollina J, Mullin JP (2023) Vertebral Bone Quality Score Independently Predicts Proximal Junctional Kyphosis and/or Failure After Adult Spinal Deformity Surgery. Neurosurgery 92:945-954. doi: 10.1227/neu.0000000000002291\u003c/li\u003e\n\u003cli\u003eGlattes RC, Bridwell KH, Lenke LG, Kim YJ, Rinella A, Edwards C, 2nd (2005) Proximal junctional kyphosis in adult spinal deformity following long instrumented posterior spinal fusion: incidence, outcomes, and risk factor analysis. 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Spine (Phila Pa 1976) 38:E803-812. doi: 10.1097/BRS.0b013e318292b7b9\u003c/li\u003e\n\u003cli\u003eLi J, Tang Z, Hu Z, Xu Y, Liang B, Qiu Y, Zhu Z, Liu Z (2024) Sagittal Imbalance in Degenerative Kyphosis: Prevalence and Implication on Postoperative Mechanical Failure. Neurosurgery. doi: 10.1227/neu.0000000000002976\u003c/li\u003e\n\u003cli\u003eLafage R, Schwab F, Glassman S, Bess S, Harris B, Sheer J, Hart R, Line B, Henry J, Burton D, Kim H, Klineberg E, Ames C, Lafage V (2017) Age-Adjusted Alignment Goals Have the Potential to Reduce PJK. Spine (Phila Pa 1976) 42:1275-1282. doi: 10.1097/brs.0000000000002146\u003c/li\u003e\n\u003cli\u003eKatsuura Y, Lafage R, Kim HJ, Smith JS, Line B, Shaffrey C, Burton DC, Ames CP, Mundis GM, Jr., Hostin R, Bess S, Klineberg EO, Passias PG, Lafage V (2022) Alignment Targets, Curve Proportion and Mechanical Loading: Preliminary Analysis of an Ideal Shape Toward Reducing Proximal Junctional Kyphosis. Global Spine J 12:1165-1174. doi: 10.1177/2192568220987188\u003c/li\u003e\n\u003cli\u003eLafage V, Schwab F, Patel A, Hawkinson N, Farcy JP (2009) Pelvic tilt and truncal inclination: two key radiographic parameters in the setting of adults with spinal deformity. Spine (Phila Pa 1976) 34:E599-606. doi: 10.1097/BRS.0b013e3181aad219\u003c/li\u003e\n\u003cli\u003eSchwab F, Lafage V, Patel A, Farcy JP (2009) Sagittal plane considerations and the pelvis in the adult patient. Spine (Phila Pa 1976) 34:1828-1833. doi: 10.1097/BRS.0b013e3181a13c08\u003c/li\u003e\n\u003cli\u003eBeyer G, Khalif\u0026eacute; M, Lafage R, Yang J, Elysee J, Frangella N, Steinmetz L, Ge D, Varlotta C, Stekas N, Manning J, Protopsaltis T, Passias P, Buckland A, Schwab F, Lafage V (2020) Pelvic Compensation in Sagittal Malalignment: How Much Retroversion Can the Pelvis Accommodate? Spine (Phila Pa 1976) 45:E203-e209. doi: 10.1097/brs.0000000000003228\u003c/li\u003e\n\u003cli\u003eLee KY, Lee JH, Im SK (2021) Optimal Lumbar Lordosis Correction for Adult Spinal Deformity with Severe Sagittal Imbalance in Patients Over Age 60: Role of Pelvic Tilt and Pelvic Tilt Ratio. Spine (Phila Pa 1976) 46:E1246-e1253. doi: 10.1097/brs.0000000000004068\u003c/li\u003e\n\u003cli\u003eMac-Thiong JM, Roussouly P, Berthonnaud E, Guigui P (2011) Age- and sex-related variations in sagittal sacropelvic morphology and balance in asymptomatic adults. Eur Spine J 20 Suppl 5:572-577. doi: 10.1007/s00586-011-1923-2\u003c/li\u003e\n\u003cli\u003ePonchelet L, Khalife M, Finoco M, Duray C, Guigui P, Ferrero E (2024) Influence of pelvic tilt correction on PJK occurrence after adult spinal deformity surgery. Eur Spine J. doi: 10.1007/s00586-024-08180-2\u003c/li\u003e\n\u003cli\u003eFerrero E, Vira S, Ames CP, Kebaish K, Obeid I, O\u0026apos;Brien MF, Gupta MC, Boachie-Adjei O, Smith JS, Mundis GM, Challier V, Protopsaltis TS, Schwab FJ, Lafage V (2016) Analysis of an unexplored group of sagittal deformity patients: low pelvic tilt despite positive sagittal malalignment. Eur Spine J 25:3568-3576. doi: 10.1007/s00586-015-4048-1\u003c/li\u003e\n\u003cli\u003eLafage R, Schwab F, Challier V, Henry JK, Gum J, Smith J, Hostin R, Shaffrey C, Kim HJ, Ames C, Scheer J, Klineberg E, Bess S, Burton D, Lafage V (2016) Defining Spino-Pelvic Alignment Thresholds: Should Operative Goals in Adult Spinal Deformity Surgery Account for Age? Spine (Phila Pa 1976) 41:62-68. doi: 10.1097/brs.0000000000001171\u003c/li\u003e\n\u003cli\u003ePark SJ, Park JS, Kang DH, Lee CS (2024) Ideal Lumbar Lordosis Correction in Patients with Adult Spinal Deformity Without Adversely Impacting Pelvic Tilt and Pelvic Incidence Minus Lumbar Lordosis: A Study of 426 Cases. Spine (Phila Pa 1976). doi: 10.1097/brs.0000000000005077\u003c/li\u003e\n\u003cli\u003ePassias PG, Jalai CM, Diebo BG, Cruz DL, Poorman GW, Buckland AJ, Day LM, Horn SR, Liabaud B, Lafage R, Soroceanu A, Baker JF, McClelland S, 3rd, Oren JH, Errico TJ, Schwab FJ, Lafage V (2019) Full-Body Radiographic Analysis of Postoperative Deviations From Age-Adjusted Alignment Goals in Adult Spinal Deformity Correction and Related Compensatory Recruitment. Int J Spine Surg 13:205-214. doi: 10.14444/6028\u003c/li\u003e\n\u003cli\u003eKwon O, Lee S, Park SM, Yeom JS, Kim HJ (2022) A Complement Type to SRS-Schwab Adult Spinal Deformity Classification: The Failure of Pelvic Compensation. Spine (Phila Pa 1976) 47:1295-1302. doi: 10.1097/brs.0000000000004404\u003c/li\u003e\n\u003cli\u003eYilgor C, Sogunmez N, Boissiere L, Yavuz Y, Obeid I, Kleinst\u0026uuml;ck F, P\u0026eacute;rez-Grueso FJS, Acaroglu E, Haddad S, Mannion AF, Pellise F, Alanay A (2017) Global Alignment and Proportion (GAP) Score: Development and Validation of a New Method of Analyzing Spinopelvic Alignment to Predict Mechanical Complications After Adult Spinal Deformity Surgery. J Bone Joint Surg Am 99:1661-1672. doi: 10.2106/jbjs.16.01594\u003c/li\u003e\n\u003cli\u003eNicholls FH, Bae J, Theologis AA, Eksi MS, Ames CP, Berven SH, Burch S, Tay BK, Deviren V (2017) Factors Associated With the Development of and Revision for Proximal Junctional Kyphosis in 440 Consecutive Adult Spinal Deformity Patients. Spine (Phila Pa 1976) 42:1693-1698. doi: 10.1097/brs.0000000000002209\u003c/li\u003e\n\u003cli\u003ePassias PG, Pierce KE, Williamson TK, Krol O, Lafage R, Lafage V, Schoenfeld AJ, Protopsaltis TS, Vira S, Line B, Diebo BG, Ames CP, Kim HJ, Smith JS, Chou D, Daniels AH, Gum JL, Shaffrey CI, Burton DC, Kelly MP, Klineberg EO, Hart RA, Bess S, Schwab FJ, Gupta MC (2023) Pelvic Nonresponse Following Treatment of Adult Spinal Deformity: Influence of Realignment Strategies on Occurrence. Spine (Phila Pa 1976) 48:645-652. doi: 10.1097/brs.0000000000004464\u003c/li\u003e\n\u003cli\u003eDave P, Lafage R, Smith JS, Line BG, Tretiakov PS, Mir J, Diebo B, Daniels AH, Gum JL, Hamilton DK, Buell T, Than KD, Fu KM, Scheer JK, Eastlack R, Mullin JP, Mundis G, Hosogane N, Yagi M, Nunley P, Chou D, Mummaneni PV, Klineberg EO, Kebaish KM, Lewis S, Hostin RA, Gupta MC, Kim HJ, Ames CP, Hart RA, Lenke LG, Shaffrey CI, Bess S, Schwab FJ, Lafage V, Burton DC, Passias PG (2024) Predictors of pelvic tilt normalization: a multicenter study on the impact of regional and lower-extremity compensation on pelvic alignment after complex adult spinal deformity surgery. J Neurosurg Spine 40:505-512. doi: 10.3171/2023.11.Spine23766\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"adult spinal deformity, pelvic compensation, proximal junctional kyphosis, pelvic tilt, S2 alar-iliac screw","lastPublishedDoi":"10.21203/rs.3.rs-6361426/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6361426/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003ePelvic compensation, as quantified by the pelvic tilt (PT), has been identified as a crucial compensatory mechanism in patients with adult spinal deformity (ASD). However, it remains uncertain whether PT has important roles in predicting the occurrence of proximal junctional kyphosis (PJK). Therefore, the purpose of this study is to analyze the influence of pelvic compensation, specifically PT, on the development of PJK in ASD patients following the second sacral alar-iliac (S2AI) fixation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eA total of 163 patients with ASD who underwent surgical treatment with S2AI fixation were retrospectively reviewed. According to the median value of pelvic tilt ratio (PTr) measured at baseline, patients were divided into the high PT group (PTr ≥ 0.6) and the low PT group (PTr \u0026lt; 0.6). Patients were further subdivided according to the degree of PT correction with the age-adjusted equation: PT = (age – 55) / 3 +20. Patients who met the exact ± 10-year threshold for age-adjusted targets were assigned to group I (ideal correction). Patients whose correction deviated by more than 10 years above or below their age were classified into group U (undercorrection) and group O (overcorrection), respectively. Demographic, surgical, and radiographic parameters and the rates of PJK were compared between groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003ePatients in the high PT group had significantly lower baseline TK, LL, as well as greater PI-LL and T1PA compared with the low PT group (all P\u0026lt;0.05). Notably, the incidence of PJK was significantly higher in the high PT group compared to the low PT group (43.2% vs. 12.2%, c²=19.612, P\u0026lt;0.001). Further stratification by age-adjusted PT correction revealed significant differences in radiographic parameters across the subsets within both the low and high PT groups. In addition, among patients in the high PT group, the incidence of PJK was significantly lower in the overcorrected PT group (11/38, 28.9%) than under- (14/23, 60.9%) and ideal correction (10/20, 50%) of PT (c²=6.449, P=0.040).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e Patients in the high PT group, representing those with exhausted pelvic compensatory capacity, had a significantly higher risk of PJK compared to the low PT group. Further stratification by postoperative age-adjusted PT correction revealed that, within the high PT group, overcorrection of PT was associated with the lowest incidence of PJK, while undercorrection presented the highest risk. These findings suggest that patients with substantial baseline pelvic decompensation may benefit from a more aggressive PT correction to provide a stable foundation for spinal constructs and improve clinical outcomes in ASD surgery.\u003c/p\u003e","manuscriptTitle":"Effect of Pelvic Compensation Capacity on Proximal Junctional Kyphosis: A Stratified Analysis of Pelvic Tilt in Adult Spinal Deformity Surgery","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-07 05:34:20","doi":"10.21203/rs.3.rs-6361426/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-06-09T01:47:41+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-08T02:27:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"9841239337868298548809000205984115135","date":"2025-05-23T22:49:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-14T12:53:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"103962590427129734447372804559209586258","date":"2025-04-06T12:55:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"88630674441177183590731262171401187083","date":"2025-04-06T04:50:54+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-04T03:39:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-04-04T02:43:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-04-04T02:20:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Orthopaedic Surgery and Research","date":"2025-04-02T12:39:01+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a9dc50ee-005e-40fc-857a-6b98b7a57fc7","owner":[],"postedDate":"May 7th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-08-07T07:20:23+00:00","versionOfRecord":{"articleIdentity":"rs-6361426","link":"https://doi.org/10.1186/s13018-025-06103-5","journal":{"identity":"journal-of-orthopaedic-surgery-and-research","isVorOnly":false,"title":"Journal of Orthopaedic Surgery and Research"},"publishedOn":"2025-07-18 16:05:34","publishedOnDateReadable":"July 18th, 2025"},"versionCreatedAt":"2025-05-07 05:34:20","video":"","vorDoi":"10.1186/s13018-025-06103-5","vorDoiUrl":"https://doi.org/10.1186/s13018-025-06103-5","workflowStages":[]},"version":"v1","identity":"rs-6361426","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6361426","identity":"rs-6361426","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}