The Impact of Intraoperative Prone Lumbar Fluoroscopy under Anesthesia on the Selection of Lowest Instrumented Vertebra and Surgical Outcomes in Adolescent Idiopathic Scoliosis with Lumbar Structural Curves

The Impact of Intraoperative Prone Lumbar Fluoroscopy under Anesthesia on the Selection of Lowest Instrumented Vertebra and Surgical Outcomes in Adolescent Idiopathic Scoliosis with Lumbar Structural Curves | 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 The Impact of Intraoperative Prone Lumbar Fluoroscopy under Anesthesia on the Selection of Lowest Instrumented Vertebra and Surgical Outcomes in Adolescent Idiopathic Scoliosis with Lumbar Structural Curves Lang Mai, Yankui Liu, Ruijue Zhu, Pan Zhou, Jiawei Di, Junlin Yang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6183873/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 31 Jul, 2025 Read the published version in BMC Musculoskeletal Disorders → Version 1 posted 10 You are reading this latest preprint version Abstract Purpose To explore the role of intraoperative prone lumbar fluoroscopy under anesthesia in guiding lowest instrumented vertebra (LIV) selection in adolescent idiopathic scoliosis (AIS) patients with lumbar structural curves and its subsequent impact on surgical outcomes.pap Methods This retrospective cohort study included 45 AIS patients with lumbar structural curves who underwent posterior spinal deformity correction surgery at the Scoliosis Center, the Third Affiliated Hospital of Sun Yat-sen University between 2020 and 2022. Based on whether the LIV selection was adjusted during surgery, patients were divided into two groups: the reduced fusion levels group (n = 26) and the non-reduced fusion levels group (n = 19). We analyzed the demographic information, radiographic data, surgical parameters (including curve correction rates, coronal and sagittal balance, and LIV-related parameters), and complication rates, with statistical significance set at p < 0.05. Results In the reduced group, 57.8% of patients had a reduced number of fused levels. When compared to the non-reduced group, there were no significant differences in the major curve correction rate (the reduced group: 77.6%, the non-reduced group: 71.7%, p = 0.95), coronal balance at final follow-up (p = 0.97), or sagittal balance at final follow-up (p = 0.64), with at least 2 years of follow-up (average 33.3 ± 15.6 months). Postoperative LIV-related parameters, including tilt angle, rotation, and the distance from the center sacral vertical line (CSVL), showed no significant differences between the two groups (p > 0.05). All patients achieved satisfactory postoperative correction, with no adverse events or revision surgeries required due to distal junctional issues. Conclusion Intraoperative prone lumbar fluoroscopy under anesthesia provides precise guidance for LIV selection, reducing the number of fused levels without compromising curve correction or overall spinal balance. This technique is both safe and effective, helping to optimize AIS surgical outcomes while preserving lumbar mobility. Further multicenter studies are needed to validate these findings and assess their long-term functional impact. Intraoperative lumbar fluoroscopy Adolescent idiopathic scoliosis Lowest instrumented vertebrae Lumbar structural curve Reduced fusion levels Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity that occurs in the prepubertal phase or before the completion of skeletal growth, with an unclear etiology. It is clinically diagnosed when the Cobb angle exceeds 10° on standing full-length posteroanterior radiograph. The global prevalence of AIS ranges from 0.47–5.3% [ 1 ] . The incidence and severity of AIS are higher in females than in males, with a female-to-male ratio ranging from 3:1 to 1.5:1 [ 2 ] . Treatment for AIS primarily involves conservative management and surgical intervention. Surgery is recommended for patients with a Cobb angle greater than 40°, particularly for those at high risk of curve progression [ 3 ] . Posterior spinal fusion with instrumentation is the most commonly performed surgical procedure for AIS [ 4 ] , aiming to restore spinal alignment and enhance stability through posterior spinal fusion. However, the selection of the lowest instrumented vertebra (LIV) is a crucial issue in the surgery [ 5 ] . Improper LIV selection can result in significant complications, including spinal imbalance, pain, and the need for revision surgery, affecting the patient's quality of life. Careful preoperative evaluation, adherence to surgical guidelines, and individualized planning are essential to ensure optimal outcomes and patient satisfaction [ 6 ] . The selection of LIV during surgery is primarily based on preoperative imaging, such as standing full-length posteroanterior and lateral radiographs, bending films, in conjunction with the patient's clinical symptoms and spinal flexibility. However, traditional imaging may not fully reflect the flexibility of spine under anesthesia. This is particularly relevant for AIS patients with lumbar structural curves, as conventional imaging may not accurately depict the three-dimensional changes in the spine, leading to suboptimal LIV selection. In recent years, intraoperative fluoroscopy (particularly lumbar fluoroscopy in the prone position) has been introduced into surgical procedures [ 7 ] . This technique serves as an adjunct to LIV selection, allowing the spinal true alignment to be evaluated under anesthesia, avoiding the influence of muscle tension on spinal flexibility. Therefore, the use of intraoperative fluoroscopy during anesthesia is of significant clinical importance in AIS surgery. This study aims to investigate the impact of intraoperative prone lumbar fluoroscopy under anesthesia on LIV selection in AIS patients with lumbar structural curves and to evaluate its clinical outcomes through mid- and long-term follow-ups. By comparing it with traditional preoperative imaging methods, this study evaluates the impact of intraoperative fluoroscopy on improving the precision of LIV selection and its subsequent effects on surgical outcomes. Methods Subjects: This is a retrospective cohort study approved by the Ethics Committee of the Third Affiliated Hospital of Sun Yat-sen University, with informed consent obtained from all patients and their families. The study included 45 AIS patients with lumbar structural curves who underwent posterior spinal deformity correction surgery at the Scoliosis Center of The Third Affiliated Hospital of Sun Yat-sen University between 2020 and 2022. The inclusion criteria were: (1) a diagnosis of adolescent idiopathic scoliosis (AIS); (2) presence of lumbar structural curves and planned for posterior spinal deformity correction surgery; (3) age at diagnosis between 10 and 18 years; (4) availability of complete preoperative imaging, including standing full-length posteroanterior and lateral radiographs, lateral bending films, full-spine CT, and intraoperative prone lumbar fluoroscopy under anesthesia. Exclusion criteria were: (1) coexisting spinal deformities or neuromuscular diseases; (2) missing intraoperative or postoperative follow-up data. LIV Selection Criteria: LIV selection was based on the following criteria: (1) The LIV should be the most cranial vertebra that is touched by the center sacral vertical line (CSVL); (2) The LIV rotation should be less than grade II (Nash-Moe classification); (3) The LIV tilt angle should be less than 25°. According to these criteria, the intraoperative LIV selection was compared with the preoperative selection. Surgical Procedure: All corrective surgeries were performed by an experienced spinal surgeon using the same surgical technique. After general anesthesia, the patient was positioned in the prone position on the operating table. The LIV was selected as described above. The upper instrumented vertebra was selected as the uppermost vertebra or one to two vertebrae above the uppermost vertebra. Pedicle screws of various sizes were selected and implanted, and pre-bent rods were positioned accordingly. The rods were used to correct spinal rotation and level the LIV using a dual-rod derotation technique. The rods were locked in place, and the correction was confirmed through intraoperative fluoroscopy. Both autologous and allogenic bone grafts were used for posterior spinal fusion. All surgeries were performed with routine intraoperative neurophysiological monitoring. Demographic and Radiological Data: Patients were divided into two groups based on a comparison of the LIV selected during surgery and the LIV determined by traditional preoperative imaging: the reduced segment group, where the number of fused segments was reduced postoperatively compared to preoperatively, and the non-reduced segment group, where the number of fused levels remained the same. The general data of the patients were recorded, including age, gender, Lenke classification, follow-up time, estimated blood loss, and operative time, and comparisons were made between the two groups. General indicators reflecting the effectiveness of scoliosis correction were recorded, including the major curve, minor curve, major curve correction rate, and minor curve correction rate. Coronal balance distance (CBD, the distance from C7 to the CSVL) and sagittal vertical axis (SVA, the distance from the S1 posterior superior corner to the C7 plumb line) were also recorded. The comparisons between the two groups were made. Additionally, LIV-related parameters were evaluated for both groups: LIV-CSVL (the distance from the final postoperative LIV to the CSVL), LIV tilt (the angle between the lower endplate of the final postoperative LIV and the horizontal plane), and LIV rotation (measured on preoperative and postoperative CT scans using the final postoperative LIV rotation). The correction rates of LIV-CSVL and LIV tilt were also calculated. Comparisons between the groups in terms of the fusion levels were also conducted. As for the evaluation of clinical complications, coronal imbalance was defined as a CBD greater than 20mm at the final follow-up, and the Adding-on phenomenon was defined as an LIV-CSVL greater than 10mm at the final follow-up. Other relevant complications were also recorded. The following data were calculated using the formulas below: Postoperative correction rate = \(\:\frac{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{C}\text{o}\text{b}\text{b}\:\text{a}\text{n}\text{g}\text{l}\text{e}-\text{P}\text{o}\text{s}\text{t}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{C}\text{o}\text{b}\text{b}\:\text{a}\text{n}\text{g}\text{l}\text{e}}{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{C}\text{o}\text{b}\text{b}\:\text{a}\text{n}\text{g}\text{l}\text{e}}\) Final follow-up correction rate = \(\:\frac{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{C}\text{o}\text{b}\text{b}\:\text{a}\text{n}\text{g}\text{l}\text{e}-\text{F}\text{i}\text{n}\text{a}\text{l}\:\text{f}\text{o}\text{l}\text{l}\text{o}\text{w}-\text{u}\text{p}\:\text{C}\text{o}\text{b}\text{b}\:\text{a}\text{n}\text{g}\text{l}\text{e}}{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{C}\text{o}\text{b}\text{b}\:\text{a}\text{n}\text{g}\text{l}\text{e}}\) Postoperative LIV tilt correction rate = \(\:\frac{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}\:\text{t}\text{i}\text{l}\text{t}-\text{P}\text{o}\text{s}\text{t}\text{o}\text{p}\text{r}\text{e}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}\:\text{t}\text{i}\text{l}\text{t}}{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}\:\text{t}\text{i}\text{l}\text{t}}\) Final follow-up LIV tilt correction rate = \(\:\frac{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}\:\text{t}\text{i}\text{l}\text{t}-\text{F}\text{i}\text{n}\text{a}\text{l}\:\text{f}\text{o}\text{l}\text{l}\text{o}\text{w}-\text{u}\text{p}\:\text{L}\text{I}\text{V}\:\text{t}\text{i}\text{l}\text{t}}{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}\:\text{t}\text{i}\text{l}\text{t}}\) Postoperative LIV-CSVL correction rate = \(\:\frac{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}-\text{C}\text{S}\text{V}\text{L}-\text{P}\text{o}\text{s}\text{t}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}-\text{C}\text{S}\text{V}\text{L}}{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}-\text{C}\text{S}\text{V}\text{L}}\) Final follow-up LIV-CSVL correction rate = \(\:\frac{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}-\text{C}\text{S}\text{V}\text{L}-\text{F}\text{i}\text{n}\text{a}\text{l}\:\text{f}\text{o}\text{l}\text{l}\text{o}\text{w}-\text{u}\text{p}\:\text{L}\text{I}\text{V}-\text{C}\text{S}\text{V}\text{L}}{\text{P}\text{r}\text{e}\text{o}\text{p}\text{e}\text{r}\text{a}\text{t}\text{i}\text{v}\text{e}\:\text{L}\text{I}\text{V}-\text{C}\text{S}\text{V}\text{L}}\) Statistical Analysis: Data were analyzed using SPSS 26.0 and GraphPad Prism 10.3.1 software. Quantitative data, such as age, Cobb angle, LIV tilt, major and minor curve Cobb angles, CBD, SVA, CSVL-LIV and postoperative and follow-up correction rates, were tested for normality. Normally distributed data were expressed as mean ± standard deviation, and differences between the two groups were compared using independent samples t-tests. Qualitative data, including gender and Lenke classification, were described as frequencies (%) and compared between groups using the Mann-Whitney U test. A p-value < 0.05 was considered statistically significant. Results The demographic and preoperative general radiological data are presented in Table 1 . A total of 45 patients (36 females and 9 males) were included in this study, with a mean age of 17.8 ± 5.9 years and an average follow-up period of 33.3 ± 15.6 months (Table 1 ). Ten patients were classified as Lenke type 3, 16 as type 4, 8 as type 5, and 11 as type 6. The average operative time for the patients was 327.8 ± 124.7 minutes, and the average blood loss was 874.4 ± 485.8 ml. There were no significant differences between the reduced and non-reduced groups in terms of age, gender, Lenke classification, operative time, or blood loss (p > 0.05). Table 1 Preoperative demographic and radiological data Parameters Overall Reduced group Non-reduced group p-value Age (years) 17.8 ± 5.9 19.0 ± 6.7 16.1 ± 4.1 0.076 Gender (n [%]) Male 9(20.0%) 4(15.4%) 5(26.3%) Female 36(80.0%) 22(84.6%) 14(73.7%) 0.371 Curve Type (n [%]) 3 10(22.2%) 7(26.9%) 3(15.8%) 4 16(35.6%) 7(26.9%) 9(47.4%) 5 8(17.8%) 5(19.3%) 3(15.8%) 6 11(24.4%) 7(26.9%) 4(21.0%) 0.952 Follow-up, months 33.3 ± 15.6 30.8 ± 15.4 36.7 ± 15.6 0.213 Estimated blood loss, ml 874.4 ± 485.8 836.1 ± 417.3 926.7 ± 574.5 0.543 Operative time, min 327.8 ± 124.7 328.8 ± 142.7 326.4 ± 98.6 0.950 The scoliosis correction indicators are shown in Fig. 1 . In the reduced group, the major curve Cobb angle was corrected from a preoperative average of 59.1° ± 11.2° to 13.8° ± 10.3° postoperatively (p < 0.0001) and 13.4° ± 9.5° at the final follow-up (p < 0.0001). In the non-reduced group, the major curve Cobb angle was corrected from 66.5° ± 11.3° preoperatively to 19.1° ± 10.7° postoperatively (p < 0.0001) and 16.6° ± 10.9° at the final follow-up (p < 0.0001) ( Fig. 1a ). In the reduced group, the minor curve Cobb angle was corrected from a preoperative average of 45.6° ± 11.4° to 11.4° ± 8.8° postoperatively (p < 0.0001) and 12.4° ± 10.2° at the final follow-up (p < 0.0001). In the non-reduced group, the minor curve Cobb angle was corrected from 51.3° ± 7.3° preoperatively to 10.5° ± 10.1° postoperatively (p < 0.0001) and 12.9° ± 9.3° at the final follow-up (p < 0.0001) ( Fig. 1b ). The postoperative major curve correction rate in the reduced group was 77.6% ± 14.7%, with no significant difference from the final follow-up correction rate of 78.95% ± 15.0% (p = 0.9522). In the non-reduced group, the postoperative major curve correction rate was 71.7% ± 14.7%, and there was no significant difference from the final follow-up rate of 76.1% ± 14.1% (p = 0.7153). The major curve, minor curve, and related correction rates were similar between the two groups, with no significant differences in postoperative or final follow-up correction rates ( Fig. 1c , d). Specifically, in the reduced group, the SVA increased from a preoperative average of 15.1 ± 13.0 mm to 28.1 ± 23.9 mm postoperatively (p = 0.0411) and 16.5 ± 13.5 mm at the final follow-up (p = 0.9675). In the non-reduced group, no significant differences were observed in the SVA between preoperative, postoperative, and follow-up measurements (p > 0.05) ( Fig. 1e ). For the CBD, the reduced group showed an increase from a preoperative average of 18.5 ± 12.4 mm to 26.3 ± 18.7 mm postoperatively (p = 0.1226) and 7.9 ± 7.8 mm at the final follow-up (p = 0.0369). In the non-reduced group, the CBD changed from 11.2 ± 7.9 mm preoperatively to 29.1 ± 20.4 mm postoperatively (p = 0.0005) and 8.9 ± 9.7 mm at the final follow-up (p = 0.0013) ( Fig. 1f ). There were no significant differences in SVA and CBD between the two groups at any time point (p > 0.05). The LIV-related data are presented in Fig. 2 . In the reduced group, the preoperative LIV tilt was corrected from an average of 19.6° ± 8.9° to 2.9° ± 3.9° postoperatively (p < 0.0001) and 2.7° ± 3.5° at the final follow-up (p < 0.0001). In the non-reduced group, the preoperative LIV tilt was corrected from 16.8° ± 5.5° to 3.9° ± 4.3° postoperatively (p < 0.0001) and 2.4° ± 3.0° at the final follow-up (p < 0.0001) ( Fig. 2a ). The correction rate for LIV tilt in the reduced group was 83.5% ± 26.2% postoperatively, with no significant difference from the final follow-up value of 75.4% ± 38.6% (p = 0.3679). In the non-reduced group, the correction rate for LIV tilt was 78.7% ± 22.7% postoperatively, with no significant difference from the final follow-up value of 89.6% ± 14.6% (p = 0.3574) ( Fig. 2b ). No significant differences in LIV tilt and its correction rates were observed between the two groups at preoperative, postoperative, and final follow-up measurements (p > 0.05). In the reduced group, the preoperative LIV rotation decreased from 12.8° ± 4.8° to 6.4° ± 3.7° postoperatively (p < 0.0001), while in the non-reduced group, the LIV rotation decreased from 6.4° ± 3.7° to 5.2° ± 3.1° postoperatively (p = 0.0243). The preoperative LIV rotation in the reduced group was significantly higher than in the non-reduced group (p = 0.0008), but there was no significant difference in postoperative LIV rotation between the two groups (p = 0.3589) ( Fig. 2c ). For LIV-CSVL, the reduced group showed a change from an average of 20.3 ± 8.6 mm preoperatively to 5.5 ± 6.2 mm postoperatively (p < 0.0001) and 6.4 ± 3.7 mm at the final follow-up (p < 0.0001). In the non-reduced group, the preoperative LIV-CSVL was 10.7 ± 5.6 mm, significantly smaller than in the reduced group (p < 0.0001). No significant difference in LIV-CSVL was observed between the two groups postoperatively (p = 0.0827), but the non-reduced group had a significantly smaller LIV-CSVL at the final follow-up (1.1 ± 2.3 mm vs. 6.4 ± 3.7 mm, p = 0.0382) ( Fig. 2d ). The postoperative LIV-CSVL correction rate in the reduced group was 74.2% ± 29.7%, with no significant difference from the final follow-up rate of 82.2% ± 29.0% (p = 0.3594). In the non-reduced group, the postoperative LIV-CSVL correction rate was 91.1% ± 19.5%, with no significant difference from the final follow-up rate of 91.8% ± 16.7% (p = 0.9479). No significant differences in LIV-CSVL correction rates were observed between the two groups at any time point (p > 0.05) ( Fig. 2e ). The final LIV distance from the stable vertebra (SV, the first vertebra intersected by the CSVL) in the reduced fusion group was − 1.6 ± 0.7 vertebrae, which was significantly higher than the non-reduced group at -1.2 ± 0.6 vertebrae (p = 0.042) ( Fig. 2f ). Regarding postoperative complications, all patients achieved satisfactory postoperative correction, with no adverse events or revision surgeries required due to distal junctional issues ( Fig. 3,4 ). Discussion This srudy compares intraoperative prone lumbar fluoroscopy with traditional imaging techniques for selecting the LIV in AIS surgery. The LIV selection adhered to strict criteria: the LIV should be the most cranial vertebra touched by CSVL ; LIV rotation should be less than grade II (Nash-Moe classification); and LIV tilt should be less than 25°. The impact of intraoperative fluoroscopy on LIV selection and its effect on deformity correction were evaluated through mid- and long-term follow-ups, achieving an average curve correction rate of 80%. Importantly, we demonstrate that intraoperative fluoroscopy can reduce the number of fused levels in AIS patients with lumbar structural curves without compromising curve correction or LIV-related outcomes. Minimizing fused levels while maximizing deformity correction is a central goal in modern orthopedic surgery [ 5 ] . For Lenke type 1–3 curves, selective thoracic fusion is often performed, while selective lumbar fusion may be considered for certain Lenke type 5 or 6 curves. In cases requiring both thoracic and lumbar fusion, LIV selection is critical in determining the extent of fusion. [ 8 ] . For patients requiring both thoracic and lumbar fusion, LIV selection almost entirely determines the fused levels. However, LIV selection criteria across various studies. Harrington introduced the concept of a "stable zone", suggesting that LIV selection within this zone is acceptable [ 9 ] . Moe and King recommended that the LIV should be located below the neutral vertebra (NV), defined as the most cranial vertebra in the major curve withou rotation [ 10 ] . Newton et al. suggested using the first vertebra touching the CSVL as the LIV, with closer proximity to the CSVL generally being preferable [ 11 ] . The stable vertebra (SV), defined as the first vertebra bisected by the CSVL in the major curve, has traditionally been considered the optimal LIV [ 12 ] . However, Ilharreborde et al. found that over 85% of the fusions extended above the SV in a 2-year follow-up study of 78 patients, with shorter fusion levels not adversely affecting clinical or radiographic outcomes [ 13 ] . Therefore, the last substantially touched vertebra (LSTV, The most cranial vertebra of the vertebral body located between the two pedicles touched by the CSVL) is considered as a viable LIV candidate, associated with lower complication rates. [ 14 ] . Additionally, LIV rotation and tilt are critical factors, with Sarwahi et al. recommending selection of the most cranial vertebra touched by the CSVL with minimal rotation and tilt to ensure long-term spinal balance [ 15 ] . Most studies rely on preoperative imaging, such as lateral and bending radiographs [ 15 – 18 ] or fulcrum bending films, for LIV decision-making [ 19 ] . Few studies have used intraoperative imaging for LIV evaluation, and even fewer have assessed postoperative outcomes based on intraoperative imaging. This study addresses these gaps by using intraoperative prone lumbar fluoroscopy under anesthesia to assess and select the LIV, with clinical outcomes analyzed through postoperative and follow-up data. Furthermore, comparison of clinical data between reduced and non-reduced fusion levels groups revealed that intraoperative prone lumbar fluoroscopy did not compromise correction efficacy. This is consistent with a recent study by Alonge et al. on reduced fusion levels [ 20 ] . Our findings showed no significant differences in major and minor curve correction rates between the two groups, indicating comparable outcomes based on Cobb angle correction. Additionally, no significant differences in CBD and SVA were found at any time point, suggesting that reducing lumbar fusion segments does not adversely affect spinal balance. Notably, intraoperative prone lumbar fluoroscopy enabled a reduction in fused lumbar segments for 57.8% of patients. The LIV distance to the SV was significantly greater in the reduced group, indicating that intraoperative fluoroscopy allows selection of a more cranial LIV, one or two vertebrae above the SV, while maintaining excellent clinical outcomes. Strict adherence to LIV selection criteria revealed that LIV rotation in intraoperative fluoroscopy imaging may appear higher compared to traditional imaging, but this did not correlate with increased postoperative decompensation or complications. Instead, LIV rotation was effectively corrected postoperatively, with no compromise in LIV tilt, LIV rotation, and LIV-CSVL correction. Although LIV-CSVL deviation was slightly greater in intraoperative imaging, likely due to the higher fusion level, postoperative LIV-CSVL correction was comparable between groups. This study has several limitations. First, as a retrospective analysis, it is susceptible to selection and information bias. A prospective study design would provide stronger evidence. Second, the sample size of 45 patients, while adequate for primary outcomes, may limit the statistical power for secondary outcomes. Additionally, the cohort may not fully represent all Lenke classification subtypes. Moreover, the study focused primarily on imaging and surgical parameters, lacking direct assessment of lumbar mobility (e.g., dynamic imaging and functional tests), which limits a comprehensive understanding of the long-term functional impact of reduced fusion levels. Finally, the single-center design may restrict the generalizability of the findings, necessitating validation through multicenter studies. In conclusion, this study demonstrates that LIV selection guided by intraoperative prone lumbar fluoroscopy is a safe and effective strategy. It allows for a reduction in lumbar fusion levels while achieving comparable major and minor curve correction outcomes to traditional methods and maintaining spinal sagittal and coronal balance. This study provides the use of intraoperative fluoroscopy as a routine tool for optimizing LIV selection, advancing personalized and outcome-driven surgical strategies in scoliosis correction. Declarations Ethics approval and consent to participate This study is approved by the Ethics Committee of the Third Affiliated Hospital of Sun Yat-sen University, with informed consent obtained from all patients and their families.The study followed the Declaration of Helsinki. Competing interests The authors declare no competing interests. Authors’information 1 Department of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University,Scoliosis Center, The Third Affiliated Hospital of Sun Yat-sen University; 2 Spine Center, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Consent for publication Written informed Consent for publication was obtained from all participants and their families Funding None. Author Contribution L. Mai designed the study, conducted data analysis, and wrote and edited the initial draft. Y. Liu was responsible for data collection and analysis, as well as drafting and revising the manuscript. R. Zhu contributed to data collection and analysis as well as revising the manuscript. P. Zhou assisted with data collection and analysis, and revised the manuscript. J. Di contributed to data collection and analysis. J. Yang designed the study, performed data processing and analysis, and revised the initial draft. Z. Huang also designed the study, handled data processing and analysis, and revised the manuscript. L. He designed the study, conducted data analysis, and wrote and edited the initial draft. Acknowledgement None Data Availability The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. References Thomas JJ, Stans AA, Milbrandt TA, Kremers HM, Shaughnessy WJ, Larson AN (2021) Trends in incidence of adolescent idiopathic scoliosis: A modern U.S. population-based study. J Pediatr Orthop 41:327–32. https://doi. org/10.1097/BPO.0000000000001808. Singh H, Shipra, Sharma V, Sharma I, Sharma A, Modeel S, et al (2022) The first study of epidemiology of adolescent idiopathic scoliosis shows lower prevalence in females of jammu and kashmir, India. Am J Transl Res 14:1100–6. 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Fujii T, Kawabata S, Suzuki S, Tsuji O, Nori S, Okada E, et al (2022) Can postoperative distal adding-on be predicted in lenke type 1B and 1C curves with intraoperative radiographs? Spine 47:E215–21. https://doi.org/10.1097/BRS.0000000000004174. Fischer CR, Kim Y (2011) Selective fusion for adolescent idiopathic scoliosis: A review of current operative strategy. Eur Spine J 20:1048–57. https://doi.org/10.1007/s00586-011-1730-9. Beauchamp EC, Lenke LG, Cerpa M, Newton PO, Kelly MP, Blanke KM, et al (2020) Selecting the “touched vertebra” as the lowest instrumented vertebra in patients with lenke type-1 and 2 curves: Radiographic results after a minimum 5-year follow-up. Journal of Bone and Joint Surgery 102:1966–73. https://doi.org/10.2106/JBJS.19.01485. King HA, Moe JH, Bradford DS, Winter RB (1983) The selection of fusion levels in thoracic idiopathic scoliosis. J Bone Joint Surg Am 65(9):1302-13. Cao K, Watanabe K, Kawakami N, Tsuji T, Hosogane N, Yonezawa I, et al (2014) Selection of lower instrumented vertebra in treating lenke type 2A adolescent idiopathic scoliosis: Spine 39:E253–61. https://doi.org/10.1097/BRS.0000000000000126. Erdemir C, Musaoğlu R, Selek Ö, Gök Ü, Şarlak AY (2015) Distal fusion level selection in lenke 1A curves according to axial plane analyses. The Spine Journal 15:2378–84. https://doi.org/10.1016/j.spinee.2015.07.004. Ilharreborde B, Ferrero E, Angelliaume A, Lefèvre Y, Accadbled F, Simon AL, et al (2017) Selective versus hyperselective posterior fusions in lenke 5 adolescent idiopathic scoliosis: Comparison of radiological and clinical outcomes. Eur Spine J 26:1739–47. https://doi.org/10.1007/s00586-017-5070-2. Qin X, Sun W, Xu L, Liu Z, Qiu Y, Zhu Z (2016) Selecting the last “substantially” touching vertebra as lowest instrumented vertebra in lenke type 1A curve: Radiographic outcomes with a minimum of 2-year follow-up. Spine 41:E742–50. https://doi.org/10.1097/BRS.0000000000001374. Sarwahi V, Hasan S, Wendolowski S, Visahan K, Atlas A, Galina J, et al (2022) A newer way of determining LIV in AIS patients: Rotation of the touched vertebrae. Spine 47:1321–7. https://doi.org/10.1097/BRS.0000000000004378. Zhuang Q, Zhang J, Wang S, Yang Y, Lin G (2021) How to select the lowest instrumented vertebra in lenke type 5 adolescent idiopathic scoliosis patients? The Spine Journal 21:141–9. https://doi.org/10.1016/j.spinee.2020.08.006. Shao X, Sui W, Deng Y, Yang J, Chen J, Yang J (2022) How to select the lowest instrumented vertebra in lenke 5/6 adolescent idiopathic scoliosis patients with derotation technique. Eur Spine J 31:996–1005. https://doi.org/10.1007/s00586-021-07040-7. Kim D-H, Hyun S-J, Lee C-H, Kim K-J (2022) The last touched vertebra on supine radiographs can be the optimal lower instrumented vertebra in adolescent idiopathic scoliosis patients. Neurospine 19:236–43. https://doi.org/10.14245/ns.2143224.612. Luk KDK, Don AS, Chong CS, Wong YW, Cheung KM (2008) Selection of fusion levels in adolescent idiopathic scoliosis using fulcrum bending prediction: A prospective study. Spine 33:2192–8. https://doi.org/10.1097/BRS.0b013e31817bd86a. Alonge E, Zhang G, Zhang H, Guo C (2024) Comparison between the lowest instrumented vertebrae L3 with the use of direct vertebrae rotation (DVR) and the lowest instrumented vertebrae L4 for non-DVR in adolescents with idiopathic scoliosis lenke 5C/6C: When LEV is L4. J Orthop Surg Res 19:492. https://doi.org/10.1186/s13018-024-04961-z. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 31 Jul, 2025 Read the published version in BMC Musculoskeletal Disorders → Version 1 posted Editorial decision: Revision requested 04 Jun, 2025 Reviews received at journal 30 Apr, 2025 Reviews received at journal 25 Apr, 2025 Reviewers agreed at journal 02 Apr, 2025 Reviewers agreed at journal 02 Apr, 2025 Reviewers invited by journal 02 Apr, 2025 Editor assigned by journal 24 Mar, 2025 Editor invited by journal 24 Mar, 2025 Submission checks completed at journal 22 Mar, 2025 First submitted to journal 22 Mar, 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-6183873","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":442014530,"identity":"9f29aa3a-8bb2-4e7f-b078-cfaadddbea81","order_by":0,"name":"Lang Mai","email":"","orcid":"","institution":"Third Affiliated Hospital of Sun Yat-sen University","correspondingAuthor":false,"prefix":"","firstName":"Lang","middleName":"","lastName":"Mai","suffix":""},{"id":442014531,"identity":"b8e2a2c3-c3ab-44b2-ac75-0cba7caac33c","order_by":1,"name":"Yankui Liu","email":"","orcid":"","institution":"Third Affiliated Hospital of Sun Yat-sen University","correspondingAuthor":false,"prefix":"","firstName":"Yankui","middleName":"","lastName":"Liu","suffix":""},{"id":442014532,"identity":"688ab003-d520-4b9a-a97d-defdec8b4620","order_by":2,"name":"Ruijue Zhu","email":"","orcid":"","institution":"Third Affiliated Hospital of Sun Yat-sen University","correspondingAuthor":false,"prefix":"","firstName":"Ruijue","middleName":"","lastName":"Zhu","suffix":""},{"id":442014533,"identity":"386b72d2-8ba5-4d72-bda1-de212ce973a0","order_by":3,"name":"Pan Zhou","email":"","orcid":"","institution":"Third Affiliated Hospital of Sun Yat-sen University","correspondingAuthor":false,"prefix":"","firstName":"Pan","middleName":"","lastName":"Zhou","suffix":""},{"id":442014534,"identity":"e71c45c9-8a31-4e49-b50d-8260c2d385c2","order_by":4,"name":"Jiawei Di","email":"","orcid":"","institution":"Third Affiliated Hospital of Sun Yat-sen University","correspondingAuthor":false,"prefix":"","firstName":"Jiawei","middleName":"","lastName":"Di","suffix":""},{"id":442014535,"identity":"5b29908a-94d8-4139-986c-a4660349d054","order_by":5,"name":"Junlin Yang","email":"","orcid":"","institution":"Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School","correspondingAuthor":false,"prefix":"","firstName":"Junlin","middleName":"","lastName":"Yang","suffix":""},{"id":442014536,"identity":"14a370f9-6e40-43e9-ade7-d8b965d27fb0","order_by":6,"name":"Zifang Huang","email":"","orcid":"","institution":"Third Affiliated Hospital of Sun Yat-sen University","correspondingAuthor":false,"prefix":"","firstName":"Zifang","middleName":"","lastName":"Huang","suffix":""},{"id":442014537,"identity":"5695b8a9-5395-4586-9cbe-0427d20fd8a7","order_by":7,"name":"Lei He","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABC0lEQVRIiWNgGAWjYBACAwbmBoaEChs5BgbGxgMwUQn8WhiBWs6kGQO1NJCghbHtUGIDkEOcFnP2xsYHD9gOpK9tPwy05c9he4MDzAdv8zDY5eHSYtlzsNkggedO7rYziQ0HGNsOJ244wJZszcOQXIzTYTcS2yQSJJ7lbjsA0tJwOMHgAI+ZNA/DAbBTsWq5/7D9R4LB4XSz8w9hDuP/hl/LDcY2hoSEwwlmN4C2MLAdZtxwgIcNv5Yzic0SCQfSDLfdANqS2JaeOPMwm7HlHINk3FqOHz748ec/G3mz8+kPH3z4Y23Pd7z54Y03FXY4taCCBIZmBgZmsFFEqQeDOuKVjoJRMApGwYgBAKu4ZkfA0vErAAAAAElFTkSuQmCC","orcid":"","institution":"Third Affiliated Hospital of Sun Yat-sen University","correspondingAuthor":true,"prefix":"","firstName":"Lei","middleName":"","lastName":"He","suffix":""}],"badges":[],"createdAt":"2025-03-08 11:38:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6183873/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6183873/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12891-025-08974-5","type":"published","date":"2025-07-31T16:21:17+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":82055594,"identity":"18484e27-30c9-4ec2-963d-199b9ac2d36a","added_by":"auto","created_at":"2025-05-06 10:24:58","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3996325,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe effect of scoliosis correction\u003c/strong\u003e. \u003cstrong\u003ea \u003c/strong\u003eComparison of the major curve Cobb angles preoperatively, postoperatively, and at the final follow-up between the reduced and non-reduced groups; \u003cstrong\u003eb \u003c/strong\u003eComparison of the minor curve Cobb angles preoperatively, postoperatively, and at the final follow-up between the reduced and non-reduced groups; \u003cstrong\u003ec \u003c/strong\u003eComparison of the major curve correction rates postoperatively and at the final follow-up between the reduced and non-reduced groups; \u003cstrong\u003ed\u003c/strong\u003e Comparison of the minor curve correction rates postoperatively and at the final follow-up between the reduced and non-reduced groups. \u003cstrong\u003ee\u003c/strong\u003e Comparison of SVA preoperatively, postoperatively, and at the final follow-up between the reduced and non-reduced groups; \u003cstrong\u003ef\u003c/strong\u003e Comparison of CBD preoperatively, postoperatively, and at the final follow-up between the reduced and non-reduced groups; ns p\u0026gt;0.05, * p\u0026lt;0.05, **p\u0026lt;0.01, ***p\u0026lt;0.001, ****p\u0026lt;0.0001\u003c/p\u003e","description":"","filename":"Figure1.tiff.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6183873/v1/ebea42a00c5aadca2cb2aaba.jpg"},{"id":82055596,"identity":"76786aee-a124-45bf-966a-fb32302e4915","added_by":"auto","created_at":"2025-05-06 10:24:58","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":3829671,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe LIV related parameters\u003c/strong\u003e. \u003cstrong\u003ea \u003c/strong\u003eComparison of LIV tilt between the reduced and non-reduced groups preoperatively, postoperatively, and at the final follow-up; \u003cstrong\u003eb \u003c/strong\u003eComparison of LIV tilt correction rates between the reduced and non-reduced groups postoperatively and at the final follow-up; \u003cstrong\u003ec\u003c/strong\u003eComparison of LIV rotation between the reduced and non-reduced groups preoperatively and postoperatively; \u003cstrong\u003ed\u003c/strong\u003e Comparison of LIV deviation from the CSVL between the reduced and non-reduced groups preoperatively, postoperatively, and at the final follow-up; \u003cstrong\u003ee \u003c/strong\u003eComparison of LIV-CSVL correction rates between the reduced and non-reduced groups postoperatively and at the final follow-up; \u003cstrong\u003ef \u003c/strong\u003eLIV distance to the stable vertebra, with a negative value indicating the LIV closer to the cranial in the reduced and non-reduced groups. ns p\u0026gt;0.05, * p\u0026lt;0.05, **p\u0026lt;0.01, ***p\u0026lt;0.001, ****p\u0026lt;0.0001\u003c/p\u003e","description":"","filename":"Figure2.tiff.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6183873/v1/54180f9b2e74d1404c0d138e.jpg"},{"id":82055592,"identity":"c88cee39-ce8d-412d-ba6b-9bf762350c8d","added_by":"auto","created_at":"2025-05-06 10:24:57","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1058425,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA typical case of Lenke type 3 (female, 15 years old). a,b\u003c/strong\u003e Preoperative full-length standing and lateral bending X-ray, L4 as planned LIV; \u003cstrong\u003ec\u003c/strong\u003e Intraoperative fluoroscopy in the prone position under anesthesia, L3 as actual LIV; \u003cstrong\u003ed\u003c/strong\u003e LIV rotation in preoperative (14°) and postoperative (7°) CT scans; \u003cstrong\u003ee\u003c/strong\u003e Intraoperative fluoroscopy immediately after deformity correction; \u003cstrong\u003ef\u003c/strong\u003e Postoperative standing X-ray at one-year follow-up；\u003cstrong\u003ePre-St: \u003c/strong\u003ePreoperative standing X-ray; \u003cstrong\u003eIntra-Flu:\u003c/strong\u003e Intraoperative prone lumbar fluoroscopy; \u003cstrong\u003eLTV: \u003c/strong\u003eLast Touch Vertebra; \u003cstrong\u003ePost-St: \u003c/strong\u003ePostoperative standing X-ray\u003c/p\u003e","description":"","filename":"Figure3.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6183873/v1/0c32399f2753ed808f7ec1a4.jpg"},{"id":82055595,"identity":"cbc18ca2-204d-4448-a332-b6565af2ac14","added_by":"auto","created_at":"2025-05-06 10:24:58","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1055163,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA typical case of Lenke type 4 (female, 11 years old). a,b\u003c/strong\u003e Preoperative full-length standing and lateral bending X-ray, L4 as planned LIV; \u003cstrong\u003ec\u003c/strong\u003e Intraoperative fluoroscopy in the prone position under anesthesia, L3 as actual LIV; \u003cstrong\u003ed\u003c/strong\u003e LIV rotation in preoperative (18°) and postoperative (4°) CT scans; \u003cstrong\u003ee \u003c/strong\u003eIntraoperative fluoroscopy immediately after deformity correction; \u003cstrong\u003ef \u003c/strong\u003ePostoperative standing X-ray at one-year follow-up;\u003cstrong\u003e Pre-St:\u003c/strong\u003e Preoperative standing X-ray; \u003cstrong\u003eIntra-Flu:\u003c/strong\u003e Intraoperative prone lumbar fluoroscopy; \u003cstrong\u003eLTV: \u003c/strong\u003eLast Touch Vertebra;\u003cstrong\u003e Post-St: \u003c/strong\u003ePostoperative standing X-ray\u003c/p\u003e","description":"","filename":"Figure4.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6183873/v1/15d182b3253ac346cf6cb1a2.jpg"},{"id":88268192,"identity":"b213830b-3510-45e1-ae89-7d9fd8eed491","added_by":"auto","created_at":"2025-08-04 16:49:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":10682360,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6183873/v1/0f7635c0-80e6-40c0-9549-db003e98cd57.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Impact of Intraoperative Prone Lumbar Fluoroscopy under Anesthesia on the Selection of Lowest Instrumented Vertebra and Surgical Outcomes in Adolescent Idiopathic Scoliosis with Lumbar Structural Curves","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAdolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity that occurs in the prepubertal phase or before the completion of skeletal growth, with an unclear etiology. It is clinically diagnosed when the Cobb angle exceeds 10\u0026deg; on standing full-length posteroanterior radiograph. The global prevalence of AIS ranges from 0.47\u0026ndash;5.3%\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. The incidence and severity of AIS are higher in females than in males, with a female-to-male ratio ranging from 3:1 to 1.5:1\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. Treatment for AIS primarily involves conservative management and surgical intervention. Surgery is recommended for patients with a Cobb angle greater than 40\u0026deg;, particularly for those at high risk of curve progression\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. Posterior spinal fusion with instrumentation is the most commonly performed surgical procedure for AIS\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e, aiming to restore spinal alignment and enhance stability through posterior spinal fusion. However, the selection of the lowest instrumented vertebra (LIV) is a crucial issue in the surgery\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. Improper LIV selection can result in significant complications, including spinal imbalance, pain, and the need for revision surgery, affecting the patient's quality of life. Careful preoperative evaluation, adherence to surgical guidelines, and individualized planning are essential to ensure optimal outcomes and patient satisfaction\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe selection of LIV during surgery is primarily based on preoperative imaging, such as standing full-length posteroanterior and lateral radiographs, bending films, in conjunction with the patient's clinical symptoms and spinal flexibility. However, traditional imaging may not fully reflect the flexibility of spine under anesthesia. This is particularly relevant for AIS patients with lumbar structural curves, as conventional imaging may not accurately depict the three-dimensional changes in the spine, leading to suboptimal LIV selection. In recent years, intraoperative fluoroscopy (particularly lumbar fluoroscopy in the prone position) has been introduced into surgical procedures\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. This technique serves as an adjunct to LIV selection, allowing the spinal true alignment to be evaluated under anesthesia, avoiding the influence of muscle tension on spinal flexibility. Therefore, the use of intraoperative fluoroscopy during anesthesia is of significant clinical importance in AIS surgery.\u003c/p\u003e \u003cp\u003eThis study aims to investigate the impact of intraoperative prone lumbar fluoroscopy under anesthesia on LIV selection in AIS patients with lumbar structural curves and to evaluate its clinical outcomes through mid- and long-term follow-ups. By comparing it with traditional preoperative imaging methods, this study evaluates the impact of intraoperative fluoroscopy on improving the precision of LIV selection and its subsequent effects on surgical outcomes.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSubjects:\u003c/h2\u003e \u003cp\u003e This is a retrospective cohort study approved by the Ethics Committee of the Third Affiliated Hospital of Sun Yat-sen University, with informed consent obtained from all patients and their families. The study included 45 AIS patients with lumbar structural curves who underwent posterior spinal deformity correction surgery at the Scoliosis Center of The Third Affiliated Hospital of Sun Yat-sen University between 2020 and 2022. The inclusion criteria were: (1) a diagnosis of adolescent idiopathic scoliosis (AIS); (2) presence of lumbar structural curves and planned for posterior spinal deformity correction surgery; (3) age at diagnosis between 10 and 18 years; (4) availability of complete preoperative imaging, including standing full-length posteroanterior and lateral radiographs, lateral bending films, full-spine CT, and intraoperative prone lumbar fluoroscopy under anesthesia. Exclusion criteria were: (1) coexisting spinal deformities or neuromuscular diseases; (2) missing intraoperative or postoperative follow-up data.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eLIV Selection Criteria:\u003c/h3\u003e\n\u003cp\u003eLIV selection was based on the following criteria: (1) The LIV should be the most cranial vertebra that is touched by the center sacral vertical line (CSVL); (2) The LIV rotation should be less than grade II (Nash-Moe classification); (3) The LIV tilt angle should be less than 25\u0026deg;. According to these criteria, the intraoperative LIV selection was compared with the preoperative selection.\u003c/p\u003e\n\u003ch3\u003eSurgical Procedure:\u003c/h3\u003e\n\u003cp\u003eAll corrective surgeries were performed by an experienced spinal surgeon using the same surgical technique. After general anesthesia, the patient was positioned in the prone position on the operating table. The LIV was selected as described above. The upper instrumented vertebra was selected as the uppermost vertebra or one to two vertebrae above the uppermost vertebra. Pedicle screws of various sizes were selected and implanted, and pre-bent rods were positioned accordingly. The rods were used to correct spinal rotation and level the LIV using a dual-rod derotation technique. The rods were locked in place, and the correction was confirmed through intraoperative fluoroscopy. Both autologous and allogenic bone grafts were used for posterior spinal fusion. All surgeries were performed with routine intraoperative neurophysiological monitoring.\u003c/p\u003e\n\u003ch3\u003eDemographic and Radiological Data:\u003c/h3\u003e\n\u003cp\u003ePatients were divided into two groups based on a comparison of the LIV selected during surgery and the LIV determined by traditional preoperative imaging: the reduced segment group, where the number of fused segments was reduced postoperatively compared to preoperatively, and the non-reduced segment group, where the number of fused levels remained the same. The general data of the patients were recorded, including age, gender, Lenke classification, follow-up time, estimated blood loss, and operative time, and comparisons were made between the two groups.\u003c/p\u003e \u003cp\u003eGeneral indicators reflecting the effectiveness of scoliosis correction were recorded, including the major curve, minor curve, major curve correction rate, and minor curve correction rate. Coronal balance distance (CBD, the distance from C7 to the CSVL) and sagittal vertical axis (SVA, the distance from the S1 posterior superior corner to the C7 plumb line) were also recorded. The comparisons between the two groups were made.\u003c/p\u003e \u003cp\u003eAdditionally, LIV-related parameters were evaluated for both groups: LIV-CSVL (the distance from the final postoperative LIV to the CSVL), LIV tilt (the angle between the lower endplate of the final postoperative LIV and the horizontal plane), and LIV rotation (measured on preoperative and postoperative CT scans using the final postoperative LIV rotation). The correction rates of LIV-CSVL and LIV tilt were also calculated. Comparisons between the groups in terms of the fusion levels were also conducted.\u003c/p\u003e \u003cp\u003eAs for the evaluation of clinical complications, coronal imbalance was defined as a CBD greater than 20mm at the final follow-up, and the Adding-on phenomenon was defined as an LIV-CSVL greater than 10mm at the final follow-up. Other relevant complications were also recorded.\u003c/p\u003e \u003cp\u003eThe following data were calculated using the formulas below:\u003c/p\u003e \u003cp\u003ePostoperative correction rate = \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{C}\\text{o}\\text{b}\\text{b}\\:\\text{a}\\text{n}\\text{g}\\text{l}\\text{e}-\\text{P}\\text{o}\\text{s}\\text{t}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{C}\\text{o}\\text{b}\\text{b}\\:\\text{a}\\text{n}\\text{g}\\text{l}\\text{e}}{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{C}\\text{o}\\text{b}\\text{b}\\:\\text{a}\\text{n}\\text{g}\\text{l}\\text{e}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003eFinal follow-up correction rate = \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{C}\\text{o}\\text{b}\\text{b}\\:\\text{a}\\text{n}\\text{g}\\text{l}\\text{e}-\\text{F}\\text{i}\\text{n}\\text{a}\\text{l}\\:\\text{f}\\text{o}\\text{l}\\text{l}\\text{o}\\text{w}-\\text{u}\\text{p}\\:\\text{C}\\text{o}\\text{b}\\text{b}\\:\\text{a}\\text{n}\\text{g}\\text{l}\\text{e}}{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{C}\\text{o}\\text{b}\\text{b}\\:\\text{a}\\text{n}\\text{g}\\text{l}\\text{e}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003ePostoperative LIV tilt correction rate =\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}\\:\\text{t}\\text{i}\\text{l}\\text{t}-\\text{P}\\text{o}\\text{s}\\text{t}\\text{o}\\text{p}\\text{r}\\text{e}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}\\:\\text{t}\\text{i}\\text{l}\\text{t}}{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}\\:\\text{t}\\text{i}\\text{l}\\text{t}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003eFinal follow-up LIV tilt correction rate =\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}\\:\\text{t}\\text{i}\\text{l}\\text{t}-\\text{F}\\text{i}\\text{n}\\text{a}\\text{l}\\:\\text{f}\\text{o}\\text{l}\\text{l}\\text{o}\\text{w}-\\text{u}\\text{p}\\:\\text{L}\\text{I}\\text{V}\\:\\text{t}\\text{i}\\text{l}\\text{t}}{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}\\:\\text{t}\\text{i}\\text{l}\\text{t}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003ePostoperative LIV-CSVL correction rate =\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}-\\text{C}\\text{S}\\text{V}\\text{L}-\\text{P}\\text{o}\\text{s}\\text{t}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}-\\text{C}\\text{S}\\text{V}\\text{L}}{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}-\\text{C}\\text{S}\\text{V}\\text{L}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003eFinal follow-up LIV-CSVL correction rate =\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}-\\text{C}\\text{S}\\text{V}\\text{L}-\\text{F}\\text{i}\\text{n}\\text{a}\\text{l}\\:\\text{f}\\text{o}\\text{l}\\text{l}\\text{o}\\text{w}-\\text{u}\\text{p}\\:\\text{L}\\text{I}\\text{V}-\\text{C}\\text{S}\\text{V}\\text{L}}{\\text{P}\\text{r}\\text{e}\\text{o}\\text{p}\\text{e}\\text{r}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e}\\:\\text{L}\\text{I}\\text{V}-\\text{C}\\text{S}\\text{V}\\text{L}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis:\u003c/h2\u003e \u003cp\u003eData were analyzed using SPSS 26.0 and GraphPad Prism 10.3.1 software. Quantitative data, such as age, Cobb angle, LIV tilt, major and minor curve Cobb angles, CBD, SVA, CSVL-LIV and postoperative and follow-up correction rates, were tested for normality. Normally distributed data were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation, and differences between the two groups were compared using independent samples t-tests. Qualitative data, including gender and Lenke classification, were described as frequencies (%) and compared between groups using the Mann-Whitney U test. A p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe demographic and preoperative general radiological data are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. A total of 45 patients (36 females and 9 males) were included in this study, with a mean age of 17.8\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9 years and an average follow-up period of 33.3\u0026thinsp;\u0026plusmn;\u0026thinsp;15.6 months (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Ten patients were classified as Lenke type 3, 16 as type 4, 8 as type 5, and 11 as type 6. The average operative time for the patients was 327.8\u0026thinsp;\u0026plusmn;\u0026thinsp;124.7 minutes, and the average blood loss was 874.4\u0026thinsp;\u0026plusmn;\u0026thinsp;485.8 ml. There were no significant differences between the reduced and non-reduced groups in terms of age, gender, Lenke classification, operative time, or blood loss (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\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\u003ePreoperative demographic and radiological data\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\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=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReduced group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNon-reduced group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\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 (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e17.8\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19.0\u0026thinsp;\u0026plusmn;\u0026thinsp;6.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e16.1\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.076\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender (n [%])\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\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 \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e9(20.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4(15.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5(26.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e36(80.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22(84.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14(73.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.371\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCurve Type (n [%])\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\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 \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e10(22.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7(26.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3(15.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e16(35.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7(26.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9(47.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e8(17.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5(19.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3(15.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e11(24.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7(26.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4(21.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.952\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\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e33.3\u0026thinsp;\u0026plusmn;\u0026thinsp;15.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e36.7\u0026thinsp;\u0026plusmn;\u0026thinsp;15.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.213\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eEstimated blood loss, ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e874.4\u0026thinsp;\u0026plusmn;\u0026thinsp;485.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e836.1\u0026thinsp;\u0026plusmn;\u0026thinsp;417.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e926.7\u0026thinsp;\u0026plusmn;\u0026thinsp;574.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.543\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOperative time, min\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e327.8\u0026thinsp;\u0026plusmn;\u0026thinsp;124.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e328.8\u0026thinsp;\u0026plusmn;\u0026thinsp;142.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e326.4\u0026thinsp;\u0026plusmn;\u0026thinsp;98.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.950\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\u003eThe scoliosis correction indicators are shown in \u003cb\u003eFig.\u0026nbsp;1\u003c/b\u003e. In the reduced group, the major curve Cobb angle was corrected from a preoperative average of 59.1\u0026deg; \u0026plusmn; 11.2\u0026deg; to 13.8\u0026deg; \u0026plusmn; 10.3\u0026deg; postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and 13.4\u0026deg; \u0026plusmn; 9.5\u0026deg; at the final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). In the non-reduced group, the major curve Cobb angle was corrected from 66.5\u0026deg; \u0026plusmn; 11.3\u0026deg; preoperatively to 19.1\u0026deg; \u0026plusmn; 10.7\u0026deg; postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and 16.6\u0026deg; \u0026plusmn; 10.9\u0026deg; at the final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) (\u003cb\u003eFig.\u0026nbsp;1a\u003c/b\u003e). In the reduced group, the minor curve Cobb angle was corrected from a preoperative average of 45.6\u0026deg; \u0026plusmn; 11.4\u0026deg; to 11.4\u0026deg; \u0026plusmn; 8.8\u0026deg; postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and 12.4\u0026deg; \u0026plusmn; 10.2\u0026deg; at the final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). In the non-reduced group, the minor curve Cobb angle was corrected from 51.3\u0026deg; \u0026plusmn; 7.3\u0026deg; preoperatively to 10.5\u0026deg; \u0026plusmn; 10.1\u0026deg; postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and 12.9\u0026deg; \u0026plusmn; 9.3\u0026deg; at the final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) (\u003cb\u003eFig.\u0026nbsp;1b\u003c/b\u003e).\u003c/p\u003e \u003cp\u003eThe postoperative major curve correction rate in the reduced group was 77.6% \u0026plusmn; 14.7%, with no significant difference from the final follow-up correction rate of 78.95% \u0026plusmn; 15.0% (p\u0026thinsp;=\u0026thinsp;0.9522). In the non-reduced group, the postoperative major curve correction rate was 71.7% \u0026plusmn; 14.7%, and there was no significant difference from the final follow-up rate of 76.1% \u0026plusmn; 14.1% (p\u0026thinsp;=\u0026thinsp;0.7153). The major curve, minor curve, and related correction rates were similar between the two groups, with no significant differences in postoperative or final follow-up correction rates (\u003cb\u003eFig.\u0026nbsp;1c\u003c/b\u003e, d). Specifically, in the reduced group, the SVA increased from a preoperative average of 15.1\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0 mm to 28.1\u0026thinsp;\u0026plusmn;\u0026thinsp;23.9 mm postoperatively (p\u0026thinsp;=\u0026thinsp;0.0411) and 16.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.5 mm at the final follow-up (p\u0026thinsp;=\u0026thinsp;0.9675). In the non-reduced group, no significant differences were observed in the SVA between preoperative, postoperative, and follow-up measurements (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (\u003cb\u003eFig.\u0026nbsp;1e\u003c/b\u003e). For the CBD, the reduced group showed an increase from a preoperative average of 18.5\u0026thinsp;\u0026plusmn;\u0026thinsp;12.4 mm to 26.3\u0026thinsp;\u0026plusmn;\u0026thinsp;18.7 mm postoperatively (p\u0026thinsp;=\u0026thinsp;0.1226) and 7.9\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8 mm at the final follow-up (p\u0026thinsp;=\u0026thinsp;0.0369). In the non-reduced group, the CBD changed from 11.2\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9 mm preoperatively to 29.1\u0026thinsp;\u0026plusmn;\u0026thinsp;20.4 mm postoperatively (p\u0026thinsp;=\u0026thinsp;0.0005) and 8.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7 mm at the final follow-up (p\u0026thinsp;=\u0026thinsp;0.0013) (\u003cb\u003eFig.\u0026nbsp;1f\u003c/b\u003e). There were no significant differences in SVA and CBD between the two groups at any time point (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eThe LIV-related data are presented in \u003cb\u003eFig.\u0026nbsp;2\u003c/b\u003e. In the reduced group, the preoperative LIV tilt was corrected from an average of 19.6\u0026deg; \u0026plusmn; 8.9\u0026deg; to 2.9\u0026deg; \u0026plusmn; 3.9\u0026deg; postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and 2.7\u0026deg; \u0026plusmn; 3.5\u0026deg; at the final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). In the non-reduced group, the preoperative LIV tilt was corrected from 16.8\u0026deg; \u0026plusmn; 5.5\u0026deg; to 3.9\u0026deg; \u0026plusmn; 4.3\u0026deg; postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and 2.4\u0026deg; \u0026plusmn; 3.0\u0026deg; at the final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) (\u003cb\u003eFig.\u0026nbsp;2a\u003c/b\u003e). The correction rate for LIV tilt in the reduced group was 83.5% \u0026plusmn; 26.2% postoperatively, with no significant difference from the final follow-up value of 75.4% \u0026plusmn; 38.6% (p\u0026thinsp;=\u0026thinsp;0.3679). In the non-reduced group, the correction rate for LIV tilt was 78.7% \u0026plusmn; 22.7% postoperatively, with no significant difference from the final follow-up value of 89.6% \u0026plusmn; 14.6% (p\u0026thinsp;=\u0026thinsp;0.3574) (\u003cb\u003eFig.\u0026nbsp;2b\u003c/b\u003e). No significant differences in LIV tilt and its correction rates were observed between the two groups at preoperative, postoperative, and final follow-up measurements (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eIn the reduced group, the preoperative LIV rotation decreased from 12.8\u0026deg; \u0026plusmn; 4.8\u0026deg; to 6.4\u0026deg; \u0026plusmn; 3.7\u0026deg; postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), while in the non-reduced group, the LIV rotation decreased from 6.4\u0026deg; \u0026plusmn; 3.7\u0026deg; to 5.2\u0026deg; \u0026plusmn; 3.1\u0026deg; postoperatively (p\u0026thinsp;=\u0026thinsp;0.0243). The preoperative LIV rotation in the reduced group was significantly higher than in the non-reduced group (p\u0026thinsp;=\u0026thinsp;0.0008), but there was no significant difference in postoperative LIV rotation between the two groups (p\u0026thinsp;=\u0026thinsp;0.3589) (\u003cb\u003eFig.\u0026nbsp;2c\u003c/b\u003e).\u003c/p\u003e \u003cp\u003eFor LIV-CSVL, the reduced group showed a change from an average of 20.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6 mm preoperatively to 5.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2 mm postoperatively (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) and 6.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7 mm at the final follow-up (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). In the non-reduced group, the preoperative LIV-CSVL was 10.7\u0026thinsp;\u0026plusmn;\u0026thinsp;5.6 mm, significantly smaller than in the reduced group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). No significant difference in LIV-CSVL was observed between the two groups postoperatively (p\u0026thinsp;=\u0026thinsp;0.0827), but the non-reduced group had a significantly smaller LIV-CSVL at the final follow-up (1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3 mm vs. 6.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7 mm, p\u0026thinsp;=\u0026thinsp;0.0382) (\u003cb\u003eFig.\u0026nbsp;2d\u003c/b\u003e). The postoperative LIV-CSVL correction rate in the reduced group was 74.2% \u0026plusmn; 29.7%, with no significant difference from the final follow-up rate of 82.2% \u0026plusmn; 29.0% (p\u0026thinsp;=\u0026thinsp;0.3594). In the non-reduced group, the postoperative LIV-CSVL correction rate was 91.1% \u0026plusmn; 19.5%, with no significant difference from the final follow-up rate of 91.8% \u0026plusmn; 16.7% (p\u0026thinsp;=\u0026thinsp;0.9479). No significant differences in LIV-CSVL correction rates were observed between the two groups at any time point (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (\u003cb\u003eFig.\u0026nbsp;2e\u003c/b\u003e). The final LIV distance from the stable vertebra (SV, the first vertebra intersected by the CSVL) in the reduced fusion group was \u0026minus;\u0026thinsp;1.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7 vertebrae, which was significantly higher than the non-reduced group at -1.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 vertebrae (p\u0026thinsp;=\u0026thinsp;0.042) (\u003cb\u003eFig.\u0026nbsp;2f\u003c/b\u003e).\u003c/p\u003e \u003cp\u003eRegarding postoperative complications, all patients achieved satisfactory postoperative correction, with no adverse events or revision surgeries required due to distal junctional issues (\u003cb\u003eFig.\u0026nbsp;3,4\u003c/b\u003e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis srudy compares intraoperative prone lumbar fluoroscopy with traditional imaging techniques for selecting the LIV in AIS surgery. The LIV selection adhered to strict criteria: the LIV should be the most cranial vertebra touched by CSVL ; LIV rotation should be less than grade II (Nash-Moe classification); and LIV tilt should be less than 25\u0026deg;. The impact of intraoperative fluoroscopy on LIV selection and its effect on deformity correction were evaluated through mid- and long-term follow-ups, achieving an average curve correction rate of 80%. Importantly, we demonstrate that intraoperative fluoroscopy can reduce the number of fused levels in AIS patients with lumbar structural curves without compromising curve correction or LIV-related outcomes.\u003c/p\u003e \u003cp\u003eMinimizing fused levels while maximizing deformity correction is a central goal in modern orthopedic surgery\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. For Lenke type 1\u0026ndash;3 curves, selective thoracic fusion is often performed, while selective lumbar fusion may be considered for certain Lenke type 5 or 6 curves. In cases requiring both thoracic and lumbar fusion, LIV selection is critical in determining the extent of fusion. \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. For patients requiring both thoracic and lumbar fusion, LIV selection almost entirely determines the fused levels. However, LIV selection criteria across various studies. Harrington introduced the concept of a \"stable zone\", suggesting that LIV selection within this zone is acceptable\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. Moe and King recommended that the LIV should be located below the neutral vertebra (NV), defined as the most cranial vertebra in the major curve withou rotation\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e. Newton et al. suggested using the first vertebra touching the CSVL as the LIV, with closer proximity to the CSVL generally being preferable\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. The stable vertebra (SV), defined as the first vertebra bisected by the CSVL in the major curve, has traditionally been considered the optimal LIV\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. However, Ilharreborde et al. found that over 85% of the fusions extended above the SV in a 2-year follow-up study of 78 patients, with shorter fusion levels not adversely affecting clinical or radiographic outcomes\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. Therefore, the last substantially touched vertebra (LSTV, The most cranial vertebra of the vertebral body located between the two pedicles touched by the CSVL) is considered as a viable LIV candidate, associated with lower complication rates.\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e. Additionally, LIV rotation and tilt are critical factors, with Sarwahi et al. recommending selection of the most cranial vertebra touched by the CSVL with minimal rotation and tilt to ensure long-term spinal balance\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eMost studies rely on preoperative imaging, such as lateral and bending radiographs\u003csup\u003e[\u003cspan additionalcitationids=\"CR16 CR17\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e or fulcrum bending films, for LIV decision-making\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. Few studies have used intraoperative imaging for LIV evaluation, and even fewer have assessed postoperative outcomes based on intraoperative imaging. This study addresses these gaps by using intraoperative prone lumbar fluoroscopy under anesthesia to assess and select the LIV, with clinical outcomes analyzed through postoperative and follow-up data.\u003c/p\u003e \u003cp\u003eFurthermore, comparison of clinical data between reduced and non-reduced fusion levels groups revealed that intraoperative prone lumbar fluoroscopy did not compromise correction efficacy. This is consistent with a recent study by Alonge et al. on reduced fusion levels\u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e. Our findings showed no significant differences in major and minor curve correction rates between the two groups, indicating comparable outcomes based on Cobb angle correction. Additionally, no significant differences in CBD and SVA were found at any time point, suggesting that reducing lumbar fusion segments does not adversely affect spinal balance.\u003c/p\u003e \u003cp\u003eNotably, intraoperative prone lumbar fluoroscopy enabled a reduction in fused lumbar segments for 57.8% of patients. The LIV distance to the SV was significantly greater in the reduced group, indicating that intraoperative fluoroscopy allows selection of a more cranial LIV, one or two vertebrae above the SV, while maintaining excellent clinical outcomes. Strict adherence to LIV selection criteria revealed that LIV rotation in intraoperative fluoroscopy imaging may appear higher compared to traditional imaging, but this did not correlate with increased postoperative decompensation or complications. Instead, LIV rotation was effectively corrected postoperatively, with no compromise in LIV tilt, LIV rotation, and LIV-CSVL correction. Although LIV-CSVL deviation was slightly greater in intraoperative imaging, likely due to the higher fusion level, postoperative LIV-CSVL correction was comparable between groups.\u003c/p\u003e \u003cp\u003eThis study has several limitations. First, as a retrospective analysis, it is susceptible to selection and information bias. A prospective study design would provide stronger evidence. Second, the sample size of 45 patients, while adequate for primary outcomes, may limit the statistical power for secondary outcomes. Additionally, the cohort may not fully represent all Lenke classification subtypes. Moreover, the study focused primarily on imaging and surgical parameters, lacking direct assessment of lumbar mobility (e.g., dynamic imaging and functional tests), which limits a comprehensive understanding of the long-term functional impact of reduced fusion levels. Finally, the single-center design may restrict the generalizability of the findings, necessitating validation through multicenter studies.\u003c/p\u003e \u003cp\u003eIn conclusion, this study demonstrates that LIV selection guided by intraoperative prone lumbar fluoroscopy is a safe and effective strategy. It allows for a reduction in lumbar fusion levels while achieving comparable major and minor curve correction outcomes to traditional methods and maintaining spinal sagittal and coronal balance. This study provides the use of intraoperative fluoroscopy as a routine tool for optimizing LIV selection, advancing personalized and outcome-driven surgical strategies in scoliosis correction.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003e This study is approved by the Ethics Committee of the Third Affiliated Hospital of Sun Yat-sen University, with informed consent obtained from all patients and their families.The study followed the Declaration of Helsinki.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eCompeting interests\u003c/strong\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003ch2\u003eAuthors\u0026rsquo;information\u003c/h2\u003e \u003cp\u003e \u003csup\u003e1\u003c/sup\u003eDepartment of Spine Surgery, The Third Affiliated Hospital of Sun Yat-sen University,Scoliosis Center, The Third Affiliated Hospital of Sun Yat-sen University;\u003c/p\u003e \u003cp\u003e \u003csup\u003e2\u003c/sup\u003eSpine Center, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine,\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eConsent for publication\u003c/h2\u003e \u003cp\u003eWritten informed Consent for publication was obtained from all participants and their families\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eNone.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eL. Mai designed the study, conducted data analysis, and wrote and edited the initial draft. Y. Liu was responsible for data collection and analysis, as well as drafting and revising the manuscript. R. Zhu contributed to data collection and analysis as well as revising the manuscript. P. Zhou assisted with data collection and analysis, and revised the manuscript. J. Di contributed to data collection and analysis. J. Yang designed the study, performed data processing and analysis, and revised the initial draft. Z. Huang also designed the study, handled data processing and analysis, and revised the manuscript. L. He designed the study, conducted data analysis, and wrote and edited the initial draft.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eNone\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eThomas JJ, Stans AA, Milbrandt TA, Kremers HM, Shaughnessy WJ, Larson AN (2021) Trends in incidence of adolescent idiopathic scoliosis: A modern U.S. population-based study. J Pediatr Orthop 41:327\u0026ndash;32. https://doi. org/10.1097/BPO.0000000000001808.\u003c/li\u003e\n\u003cli\u003eSingh H, Shipra, Sharma V, Sharma I, Sharma A, Modeel S, et al (2022) The first study of epidemiology of adolescent idiopathic scoliosis shows lower prevalence in females of jammu and kashmir, India. Am J Transl Res 14:1100\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eNegrini S, Donzelli S, Aulisa AG, Czaprowski D, Schreiber S, de Mauroy JC, et al (2018) 2016 SOSORT guidelines: Orthopaedic and rehabilitation treatment of idiopathic scoliosis during growth. Scoliosis Spinal Disord 13:3. https://doi. org/10.1186/s13013-017-0145-8.\u003c/li\u003e\n\u003cli\u003eWeinstein SL, Dolan LA, Cheng JC, Danielsson A, Morcuende JA (2008) Adolescent idiopathic scoliosis. Lancet 371(9623):1527-37. https://doi.org/10.1016/S0140-6736(08)60658-3. \u003c/li\u003e\n\u003cli\u003eBaghdadi S, Baldwin K. Selection of fusion levels in adolescent idiopathic scoliosis (2023) Curr Rev Musculoskelet Med 17:23\u0026ndash;36. https://doi. org/10.1007/s12178-023-09876-6.\u003c/li\u003e\n\u003cli\u003eLarson AN, Marks MC, Gonzalez Sepulveda JM, Newton PO, Devlin VJ, Peat R, et al (2024) Non-fusion versus fusion surgery in pediatric idiopathic scoliosis: What trade-offs in outcomes are acceptable for the patient and family? Journal of Bone and Joint Surgery 106:2\u0026ndash;9. https://doi.org/10.2106/JBJS.23.00503.\u003c/li\u003e\n\u003cli\u003eFujii T, Kawabata S, Suzuki S, Tsuji O, Nori S, Okada E, et al (2022) Can postoperative distal adding-on be predicted in lenke type 1B and 1C curves with intraoperative radiographs? Spine 47:E215\u0026ndash;21. https://doi.org/10.1097/BRS.0000000000004174.\u003c/li\u003e\n\u003cli\u003eFischer CR, Kim Y (2011) Selective fusion for adolescent idiopathic scoliosis: A review of current operative strategy. Eur Spine J 20:1048\u0026ndash;57. https://doi.org/10.1007/s00586-011-1730-9.\u003c/li\u003e\n\u003cli\u003eBeauchamp EC, Lenke LG, Cerpa M, Newton PO, Kelly MP, Blanke KM, et al (2020) Selecting the \u0026ldquo;touched vertebra\u0026rdquo; as the lowest instrumented vertebra in patients with lenke type-1 and 2 curves: Radiographic results after a minimum 5-year follow-up. Journal of Bone and Joint Surgery 102:1966\u0026ndash;73. https://doi.org/10.2106/JBJS.19.01485.\u003c/li\u003e\n\u003cli\u003eKing HA, Moe JH, Bradford DS, Winter RB (1983) The selection of fusion levels in thoracic idiopathic scoliosis. J Bone Joint Surg Am 65(9):1302-13. \u003c/li\u003e\n\u003cli\u003eCao K, Watanabe K, Kawakami N, Tsuji T, Hosogane N, Yonezawa I, et al (2014) Selection of lower instrumented vertebra in treating lenke type 2A adolescent idiopathic scoliosis: Spine 39:E253\u0026ndash;61. https://doi.org/10.1097/BRS.0000000000000126.\u003c/li\u003e\n\u003cli\u003eErdemir C, Musaoğlu R, Selek \u0026Ouml;, G\u0026ouml;k \u0026Uuml;, Şarlak AY (2015) Distal fusion level selection in lenke 1A curves according to axial plane analyses. The Spine Journal 15:2378\u0026ndash;84. https://doi.org/10.1016/j.spinee.2015.07.004.\u003c/li\u003e\n\u003cli\u003eIlharreborde B, Ferrero E, Angelliaume A, Lef\u0026egrave;vre Y, Accadbled F, Simon AL, et al (2017) Selective versus hyperselective posterior fusions in lenke 5 adolescent idiopathic scoliosis: Comparison of radiological and clinical outcomes. Eur Spine J 26:1739\u0026ndash;47. https://doi.org/10.1007/s00586-017-5070-2.\u003c/li\u003e\n\u003cli\u003eQin X, Sun W, Xu L, Liu Z, Qiu Y, Zhu Z (2016) Selecting the last \u0026ldquo;substantially\u0026rdquo; touching vertebra as lowest instrumented vertebra in lenke type 1A curve: Radiographic outcomes with a minimum of 2-year follow-up. Spine 41:E742\u0026ndash;50. https://doi.org/10.1097/BRS.0000000000001374.\u003c/li\u003e\n\u003cli\u003eSarwahi V, Hasan S, Wendolowski S, Visahan K, Atlas A, Galina J, et al (2022) A newer way of determining LIV in AIS patients: Rotation of the touched vertebrae. Spine 47:1321\u0026ndash;7. https://doi.org/10.1097/BRS.0000000000004378.\u003c/li\u003e\n\u003cli\u003eZhuang Q, Zhang J, Wang S, Yang Y, Lin G (2021) How to select the lowest instrumented vertebra in lenke type 5 adolescent idiopathic scoliosis patients? The Spine Journal 21:141\u0026ndash;9. https://doi.org/10.1016/j.spinee.2020.08.006.\u003c/li\u003e\n\u003cli\u003eShao X, Sui W, Deng Y, Yang J, Chen J, Yang J (2022) How to select the lowest instrumented vertebra in lenke 5/6 adolescent idiopathic scoliosis patients with derotation technique. Eur Spine J 31:996\u0026ndash;1005. https://doi.org/10.1007/s00586-021-07040-7.\u003c/li\u003e\n\u003cli\u003eKim D-H, Hyun S-J, Lee C-H, Kim K-J (2022) The last touched vertebra on supine radiographs can be the optimal lower instrumented vertebra in adolescent idiopathic scoliosis patients. Neurospine 19:236\u0026ndash;43. https://doi.org/10.14245/ns.2143224.612.\u003c/li\u003e\n\u003cli\u003eLuk KDK, Don AS, Chong CS, Wong YW, Cheung KM (2008) Selection of fusion levels in adolescent idiopathic scoliosis using fulcrum bending prediction: A prospective study. Spine 33:2192\u0026ndash;8. https://doi.org/10.1097/BRS.0b013e31817bd86a.\u003c/li\u003e\n\u003cli\u003eAlonge E, Zhang G, Zhang H, Guo C (2024) Comparison between the lowest instrumented vertebrae L3 with the use of direct vertebrae rotation (DVR) and the lowest instrumented vertebrae L4 for non-DVR in adolescents with idiopathic scoliosis lenke 5C/6C: When LEV is L4. J Orthop Surg Res 19:492. https://doi.org/10.1186/s13018-024-04961-z.\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":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Intraoperative lumbar fluoroscopy, Adolescent idiopathic scoliosis, Lowest instrumented vertebrae, Lumbar structural curve, Reduced fusion levels","lastPublishedDoi":"10.21203/rs.3.rs-6183873/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6183873/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo explore the role of intraoperative prone lumbar fluoroscopy under anesthesia in guiding lowest instrumented vertebra (LIV) selection in adolescent idiopathic scoliosis (AIS) patients with lumbar structural curves and its subsequent impact on surgical outcomes.pap\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis retrospective cohort study included 45 AIS patients with lumbar structural curves who underwent posterior spinal deformity correction surgery at the Scoliosis Center, the Third Affiliated Hospital of Sun Yat-sen University between 2020 and 2022. Based on whether the LIV selection was adjusted during surgery, patients were divided into two groups: the reduced fusion levels group (n\u0026thinsp;=\u0026thinsp;26) and the non-reduced fusion levels group (n\u0026thinsp;=\u0026thinsp;19). We analyzed the demographic information, radiographic data, surgical parameters (including curve correction rates, coronal and sagittal balance, and LIV-related parameters), and complication rates, with statistical significance set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eIn the reduced group, 57.8% of patients had a reduced number of fused levels. When compared to the non-reduced group, there were no significant differences in the major curve correction rate (the reduced group: 77.6%, the non-reduced group: 71.7%, p\u0026thinsp;=\u0026thinsp;0.95), coronal balance at final follow-up (p\u0026thinsp;=\u0026thinsp;0.97), or sagittal balance at final follow-up (p\u0026thinsp;=\u0026thinsp;0.64), with at least 2 years of follow-up (average 33.3\u0026thinsp;\u0026plusmn;\u0026thinsp;15.6 months). Postoperative LIV-related parameters, including tilt angle, rotation, and the distance from the center sacral vertical line (CSVL), showed no significant differences between the two groups (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). All patients achieved satisfactory postoperative correction, with no adverse events or revision surgeries required due to distal junctional issues.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eIntraoperative prone lumbar fluoroscopy under anesthesia provides precise guidance for LIV selection, reducing the number of fused levels without compromising curve correction or overall spinal balance. This technique is both safe and effective, helping to optimize AIS surgical outcomes while preserving lumbar mobility. Further multicenter studies are needed to validate these findings and assess their long-term functional impact.\u003c/p\u003e","manuscriptTitle":"The Impact of Intraoperative Prone Lumbar Fluoroscopy under Anesthesia on the Selection of Lowest Instrumented Vertebra and Surgical Outcomes in Adolescent Idiopathic Scoliosis with Lumbar Structural Curves","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-06 10:24:53","doi":"10.21203/rs.3.rs-6183873/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-06-04T08:49:00+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-30T21:40:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-25T08:32:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"161619542244249510828787703680418738236","date":"2025-04-02T18:43:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"174505408843040241611895140903463490476","date":"2025-04-02T15:20:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-02T10:33:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-03-24T13:04:54+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-03-24T11:00:48+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-22T07:11:42+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2025-03-22T07:10:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f76ce62e-2c18-4715-8920-28e1aaea6879","owner":[],"postedDate":"May 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-08-04T16:42:31+00:00","versionOfRecord":{"articleIdentity":"rs-6183873","link":"https://doi.org/10.1186/s12891-025-08974-5","journal":{"identity":"bmc-musculoskeletal-disorders","isVorOnly":false,"title":"BMC Musculoskeletal Disorders"},"publishedOn":"2025-07-31 16:21:17","publishedOnDateReadable":"July 31st, 2025"},"versionCreatedAt":"2025-05-06 10:24:53","video":"","vorDoi":"10.1186/s12891-025-08974-5","vorDoiUrl":"https://doi.org/10.1186/s12891-025-08974-5","workflowStages":[]},"version":"v1","identity":"rs-6183873","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6183873","identity":"rs-6183873","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}