Radiographic Parameters and feasibility analysis of dual sacral-2 alar-iliac screw fixation using three-dimensional digital technology

Radiographic Parameters and feasibility analysis of dual sacral-2 alar-iliac screw fixation using three-dimensional digital technology | 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 Radiographic Parameters and feasibility analysis of dual sacral-2 alar-iliac screw fixation using three-dimensional digital technology Mengqi Xie, Chao Chen, Xun Sun, Xiaoman Dong, Zhi Wang, Dong Zhao, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3927343/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective The purpose of this study was to evaluate the feasibility and the trajectories of dual sacral-2 alar-iliac (S2AI) screw fixation with three-dimensional digital technology simulation analysis. Methods The pelvic computed tomography scan data of 60 (30 men and 30 women, age: 25–86 years) individuals were selected and reconstructed. The trajectories of dual S2AI screws were plotted using three-dimensional reconstruction software. A cylinder with a radius of 5 mm was selected to simulate screw placement. If screw placement based on the cylinder with 5 mm radius failed, selected a cylinder with a radius of 4.5 mm or 4 mm. Dual S2AI trajectories were simulated, the maximum length and width of the trajectories were ensured, and their parameters were precisely measured. All parameters were measured in the three-dimensional image, including distance parameters, radius and angles. Results The placement of dual S2AI screws on the same side could be achieved in all individuals. No significant differences were found between the male and female regarding the head inclination angle, abduction angle, and total length or thread length of screws in the same position ( P > 0.05). LH(the shortest distance from the greater sciatic notch to the cross-section of the screw trajectory)were17.52 ± 3.96 mm and 14.18 ± 2.92 mm in L1,28.19 ± 2.58 mm and 25.54 ± 4.15 mm in L2, 16.09 ± 4.08 mm and 14.71 ± 3.94 mm in R1, 26.90 ± 3.76 mm and 24.59 ± 2.85 mm in R2 in male and female models, respectively. The shortest distance from the greater sciatic notch to the cross-section of the screw trajectory differed significantly between the sexes ( P < 0.05). Conclusion Using a radius of 4 mm (minimum diameter of S2AI screw) as a standard, it is feasible to place two S2AI screws on the same side for the Chinese adult. Screw placement can be achieved by trisecting the lateral process of S1-S2, with one screw inserted in the bottom third and the other in the upper third. Furthermore, preoperative three-dimensional digital technology simulation analysis can effectively simulate the dual S2AI screws trajectories on the same side, and they can provide accurate data for clinical applications. Spine surgery Spinopelvic fixation Dual sacral-2 alar-iliac screw Screw trajectory Three-dimensional Mimics Figures Figure 1 Figure 2 Figure 3 Introduction Long-level fusion across the lumbosacral junction and strong spin-pelvic fixation are frequently required in complex spinal deformity and tumor surgery. The spin-pelvic fixation technique has provided a new option for long-level spinal fixation and fusion (comprising 5 or more vertebral bodies), as well as the treatment of severe spondylolisthesis, lumbar deformity, pelvic obliquity, severe osteoporosis and lumbosacral fixation after tumor development and infection[ 1 ]. The Galveston technique had been widely used in spin-pelvic fixation technique since introduced by Allen and Ferguson in1984[ 2 ]. Iliac screws are safe during insertion and associated with low rates of long-term implant complications. This led some surgeons to abandon the Galveston technique in favor of Iliac screws[ 3 ]. Sacral and lumbar screw fixation may contribute to spin-pelvic construct stability, but need additional Iliac screws[ 4 ]. In the above techniques, either a large amount of soft tissue is stripped or the internal fixations are difficult to install, owing the need for separate connectors[ 5 ]. Therefore, it would be of great significance to find a safe and effective solution for spin-pelvic fixation. Sponsell et al. [ 6 , 7 ]first reported the application of sacral-2 alar-iliac (S2AI) screws for pelvic fixation in 2009.This method provides a distal fixation plan for internal fixation in adults with degenerative scoliosis and kyphosis. It has achieved good clinical results and has been widely used in recent years. S2AI screw fixation technique can reduce the range of soft tissue stripping[ 7 ], and it has a higher fixation strength when the screw passing through the three layers of dense cortical bone of the sacroiliac joint[ 8 ]. Furthermore, any lateral connector is not required during the operation, this can help reduce the difficulty of surgery and bring down the risk of loosening and pulling out of the internal fixation. In addition, due to the lower risk of reoperation, the probability of secondary injury and infection are reduced. Consequently, the application of S2AI screws is becoming increasingly common[ 9 , 10 ]. The placement method of S2AI screws has obvious advantages in fixation and preventing screw protrusion, however, due to the complex anatomical structure of the sacropelvic, the proximity of screw placement sites to important anatomical structures, and large individual differences[ 11 ] comprise the main challenges of S2AI screw placement at present. Additionally, for some patients with complex revisions or severe deformities, a single S2AI screw often cannot provide strong adequate biomechanical stability. Therefore, stronger spin-pelvic fixation may be required under some circumstances. Although there are many studies on the screw trajectory of single S2AI screw placement, there are few reports about the application of dual S2AI screws[ 11 , 12 ], and the specific parameters of the trajectory of dual S2AI screws have not been described. Dual S2 Alar-Iliac Screw Technique (Dual S2AI) was first reported by Lenke LG et al.[ 12 ] in 2020, as part of long spinal constructs in patients with significant adult spinal deformity, it can provide a safe and effective long-term correction and clinical success. However further study is necessary to demonstrate this thesis. However, to our knowledge, no conclusive study is available on three-dimensional measurement and the simulation of screw trajectories in the clinical application of unilateral dual S2AI screws. In previous clinical applications of S2AI screws, clinicians were mostly concerned about the damage to the cortical bone of the greater sciatic notch, which could damage the sciatic nerve below the greater sciatic notch, the internal iliac artery and vein, and the posterior and posterosuperior supragluteal neurovascular bundles, injuries that often lead to more serious clinical consequences[ 13 ]. Therefore, a elaborate start point and trajectory is crucial to ensure patient safety in the placement of unilateral dual S2AI screws. To sum up, the aims of our study are (1) to investigate the feasibility of unilateral dual S2AI screws in the Chinese adult population with Mimics software, (2) to simulate screw trajectories and collect three-dimensional measurement data, analysis the differences in distance parameters, radius and angle between men and women in the same location, as well as the differences between different sides at the same level, (3) to provide accurate reference data for the clinical application of this technique. Materials and methods Study subjects In this study, the three-dimensional pelvic computed tomography (CT) scans of 60 adult patients were randomly selected from patients undergoing three-dimensional pelvic CT scans at our hospital from January 2020 to June 2020. Three-dimensional pelvic CT scans should include the sacrum, coccyx, and hip bones. The exclusion criteria were as follows: I. patients with a history metabolic bone disease, Ⅱ. long-term use of hormones, Ⅲ.sacral tumors and infections, Ⅳ. pelvic deformities, Ⅴ. fractures and hip dislocations, Ⅵ. lumbosacral pelvic trauma or surgery. Imaging reconstruction The above CT scans (in DICOM format) were imported into Mimics 20.0 software (Materialise, Belgium; version 20.0) for three-dimensional reconstruction of the pelvis (sacrum and hip). Sagittal plane and coronal plane were determined on the reconstructed pelvis image for calculation of the orientation of each screw trajectory (Fig. 1 A). To avoid bias brought by the deformity of pelvic tilt rotation and torsion, the sagittal plane bisected the pelvis, while the coronal plane passed through the anterior superior iliac spine and the anterior margin of the pubic symphysis and was perpendicular to the sagittal plane. Simulation and analysis of L1 L2 R1 R2 screw channels The entry points of the four S2AI screws were determined on the reconstructed three-dimensional images[ 11 , 12 ]. The lateral sacral crest between the S1 and S2 foramina in the mediolateral direction was trisected, the entry point of the first screw was located in the lower third and defined as L1 or R1, and the the second screw was in the upper third and defined as L2 or R2 (Fig. 1 B). Because the radius of the tail end of an S2AI screw is 5 mm, if the measured distance between the entry points of two screws on the same side is greater than 10 mm, screw placement can be completed. A cylinder with a radius of 5 mm was selected to simulate screw placement. If screw placement based on a cylinder with a 5 mm radius failed, then a cylinder with a radius of 4.5 mm or 4 mm was selected. Screw placement simulation started at L1 or R1, and the coordinates of L1 or R1 were used to simulate one end of the screw. The screw placement simulation was performed by adjusting the screw position and diameter, and the same method was used to complete simulated placement of all four screws (Fig. 2 A/B). Ensuring simulated screw trajectory did not penetrate the cortical bone of the pelvis or interfered with each other. The cross section of each screw trajectory passed through the centerline of the cylinder of the screw trajectory and was perpendicular to the sagittal plane (Fig. 2 C). Data metrics The ideal trajectory of each simulated screw trajectory was as follows (Fig. 3 ): Ⅰ. Screw length(L): the distance between two points, that is, the total length of the simulated trajectory (the distance from the optimal entry point to the exit point); Ⅱ. Screw trajectory radius(R): the radius of the optimal cylinder for screw trajectory simulation; Ⅲ. LE: the shortest distance from the edge of the ipsilateral sacral foramen to the simulated screw trajectory; Ⅳ. Length in sacrum(LS): the length of the optimal screw trajectory in the sacrum; Ⅴ. Length in ilium(LI): the length of the optimal screw trajectory in the ilium; Ⅵ. LP: the shortest length from the screw entry point to the median sagittal plane; Ⅶ. LH: the shortest distance from the greater sciatic notch to the cross-section angle between the screw trajectory; Ⅷ. Abduction angle (α): the angle between the optimal screw trajectory and the median sagittal plane; Ⅸ. Caudal deviation angle(β): the angle between the optimal screw trajectory and the coronal plane. All CT data sets were measured by a consultant radiologist and a spine surgeon independently. A descriptive study of the variables was carried out. The concordance between the different scores was analyzed through the kappa concordance index. Statistical analysis Statistical analyses were performed using IBM SPSS Statistics for Windows (Version 21.0; IBM, Armonk, NY, USA). All parameters are expressed as the mean ± standard deviation. To test the significance of the observed differences between men and women, an independent-samples t-test was used. To test the significance of the observed differences in different screw trajectories, a paired-samples t-test was employed. P < 0.05 was considered statistically significant. Results A total of 60 patients (30 males and 30 females aged 25–86 years, with a mean age of 61.6 years) were enrolled in this study. Their ages ranged from 25 to 86 years, with an average age of 62.03 ± 12.91 years. The results of the normality test showed that the age distribution conformed to a normal distribution (Kolmogorov-Smirnov Z = 1.323, P = 0.060). Unilateral dual S2AI screws could be successfully simulated in all patients in this group using Mimics three-dimensional reconstruction software, and the relevant data of the optimal screw trajectories could be successfully measured. The measured distance between the entry points of two screws on the same side was greater than 10 mm in all patients. As shown in Table 1 , the mean distances were all greater than 11.5 mm in each group, and no significant difference was found between men and women on the left side, while a significant difference between men and women was identified on the right side. The results provide a basis for accommodating two S2AI screw tails in the screw entry point area. No significantly different in the distance between entry points of the two screws was identified between different sides( P >0.05). According to the consistency test, the Kappa consistency test value of radiologist and spine surgeon results was 0.821, indicating a general consistency. Table 1 The measured distance between the entry points of two screws Sex N Mean ± SD t P Screw entry points (L) Male 30 11.64 ± 0.59 -0.061 0.952 (mm) Female 30 11.65 ± 0.87 Screw entry points (R) Male 30 11.53 ± 0.62 -2.493 0.016 * (mm) Female 30 11.9 ± 0.52 Note: *P < 0.05 indicates statistically significant difference Table 2 Comparison of the parameters of the screw at L1 between men and women Variable Men (n = 30) Women (n = 30) t P L(mm) 115.16 ± 9.36 114.62 ± 9.7 0.219 0.827 LE(mm) 11.47 ± 9.7 10.02 ± 2.44 0.795 0.430 LH(mm) 17.52 ± 3.96 14.18 ± 2.92 3.706 0.000* LI(mm) 80.36 ± 7.23 81.16 ± 9.52 -0.367 0.715 LP(mm) 26.01 ± 5.99 28.58 ± 4.33 -1.910 0.061 LS(mm) 34.89 ± 6.08 33.43 ± 6.22 0.920 0.362 α (°) 38.68 ± 4.65 37.98 ± 4.11 0.621 0.537 β(°) 56.16 ± 6 56.37 ± 9.22 -0.103 0.918 Note: * P < 0.05 indicates statistically significant difference L: Screw length, LE: the shortest distance from the edge of the ipsilateral sacral foramen to the simulated screw trajectory, LS: Length in sacrum, LI: Length in ilium, LP: the shortest length from the screw entry point to the median sagittal plane, LH: the shortest distance from the greater sciatic notch to the cross-section angle between the screw trajectory,α:Abduction angle, β:Caudal deviation angle Digital measurements of L1 screw trajectory Based on the simulated trajectory of the L1 screw, the average α angle on the men and women respectively was 38.68 ± 4.65°and 37.98 ± 4.11°. The average β angle on the men and women respectively was 56.16 ± 6°and 56.37 ± 9.22°. With respect to distance parameters, the average total length of the simulated trajectory was approximately 115.16 ± 9.36 mm in males and 114.62 ± 9.7 mm in females (Table 3 ). No significant difference in L, LE, LI, LP, LS, α or β angles was identified between sexes ( P > 0.05). LH values were 17.52 ± 3.96 in men and 14.18 ± 2.92 in women; therefore, the distance from the greater sciatic notch to the cross-section of the L1 screw trajectory was significantly longer in men than in women ( P < 0.001)(Table 3 ). Table 3 Comparison of the parameters of the screw at L2 between men and women Variable Men (n = 30) Women (n = 30) t P L (mm) 102.20 ± 8.66 101.86 ± 11.11 0.132 0.895 LE (mm) 8.34 ± 1.64 9.12 ± 1.85 -1.714 0.092 LH (mm) 28.19 ± 2.58 25.54 ± 4.15 2.964 0.004 * LI (mm) 74.84 ± 14.95 65.56 ± 12.20 2.635 0.011* LP (mm) 27.14 ± 5.85 28.48 ± 4.37 -1.009 0.317 LS (mm) 31.43 ± 5.54 34.20 ± 5.39 -1.962 0.055 α(°) 45.65 ± 3.82 44.28 ± 4.40 1.287 0.203 β(°) 56.15 ± 7.63 56.34 ± 10.83 -0.077 0.939 Note: * P < 0.05 indicates statistically significant difference Digital measurements of L2 screw trajectory Based on the simulated trajectory of the L2 screw, the average α angle on the men and women respectively was 45.65 ± 3.82°and 44.28 ± 4.40°. The average β angle on the men and women respectively was 56.15 ± 7.63°and 56.34 ± 10.83°. With respect to distance parameters, the average total length of the simulated trajectory was approximately 102.20 ± 8.66 mm in males and 101.86 ± 11.11 mm in females (Table 3 ). No significant difference in L, LE, LP, LS, α or β angles was found between sexes ( P > 0.05). LH values were 28.19 ± 2.58 in men and 25.54 ± 4.15 in women; therefore, the distance from the greater sciatic notch to the cross-section of the L2 screw trajectory was significantly longer in men than in women ( P < 0.005). LI values were 74.84 ± 14.95 in men and 65.56 ± 12.20 in women; therefore, the simulated screw trajectory for L2 was significantly longer in the iliac bones of men than in those of women ( P < 0.05) (Table 3 ). Digital measurements of R1 screw trajectory Based on the simulated trajectory of the R1 screw, the average α angle on the men and women respectively was 38.43 ± 3.37°and 37.74 ± 3.53°. The average β angle on the men and women respectively was 53.10 ± 7.81°and 57.17 ± 9.26°. With respect to distance parameters, the average total length of the simulated trajectory was approximately 116.49 ± 11.69 mm in males and 119.12 ± 9.38 mm in females (Table 4 ). No significant difference in L, LE, LI, LP, LS, α and β angles was found between sexes ( P > 0.05). LH values were 16.09 ± 4.08 in men and 14.71 ± 3.94 in women; therefore, the distance from the greater sciatic notch to the cross-section of the R1 screw trajectory was significantly longer in men than in women ( P < 0.001) (Table 4 ). Table 4 Comparison of the parameters of the screw at R1 between men and women Variable Men (n = 30) Women (n = 30) t P L(mm) 116.49 ± 11.69 119.12 ± 9.38 -0.963 0.340 LE(mm) 7.68 ± 1.98 8.02 ± 2.19 -0.620 0.538 LH(mm) 16.09 ± 4.08 14.71 ± 3.94 1.339 0.029* LI(mm) 83.48 ± 8.42 86.93 ± 9.19 -1.515 0.135 LP(mm) 26.48 ± 2.47 28.10 ± 4.40 -1.759 0.085 LS(mm) 34.55 ± 6.47 33.56 ± 4.9 0.672 0.504 α(°) 38.43 ± 3.37 37.74 ± 3.53 0.771 0.444 β(°) 53.10 ± 7.81 57.17 ± 9.26 -1.838 0.071 Note: * P < 0.05 indicates statistically significant difference Digital measurements of R2 screw trajectory Based on the simulated trajectory of the R2 screw, the average α angle on the men and women respectively was 45.89 ± 3.48°and 43.87 ± 4.91°. The average β angle on the men and women respectively was 55.37 ± 7.96°and 55.34 ± 10.62°. With respect to distance parameters, the average total length of the simulated trajectory was approximately 102.87 ± 10.95 mm in males and 107.09 ± 11.51 mm in females (Table 5 ). No significant difference in L, LE, LP, LS, α and β angles between sexes ( P > 0.05). LH values were 26.90 ± 3.76 in men and 24.59 ± 2.85 in women; therefore, a significant difference between sexes was noted ( P < 0.05). The LI values were 68.72 ± 11.70 in men and 76.84 ± 9.52 in women; therefore, the simulated screw trajectory for R2 was longer in the iliac bones of men than in those of women ( P < 0.05) (Table 5 ). Table 5 Comparison of various parameters at the R2 position between men and women Variable Men (n = 30) Women (n = 30) T P L(mm) 102.87 ± 10.95 107.09 ± 11.51 -1.454 0.151 LE(mm) 8.41 ± 2.00 8.62 ± 1.95 -0.420 0.676 LH(mm) 26.90 ± 3.76 24.59 ± 2.85 2.683 0.009* LI(mm) 68.72 ± 11.70 76.84 ± 9.52 -2.950 0.005* LP(mm) 27.74 ± 2.95 33.22 ± 15.01 -1.965 0.058 LS(mm) 33.16 ± 6.32 32.13 ± 4.70 0.714 0.478 α(°) 45.89 ± 3.48 43.87 ± 4.91 1.830 0.072 β(°) 55.37 ± 7.96 55.34 ± 10.62 0.013 0.990 Note: * P < 0.05 indicates statistically significant difference Next, the left and right screw trajectories were compared. Tables 6 and 7 compare the measured parameters of the screws on different sides. The comparisons between L1 and R1 and between L2 and R2 showed no statistical differences for any of the measured items ( P > 0.05). Tables 8 and 9 compare the two screw trajectories on the same side. Statistical differences were observed between the two S2AI screw trajectories on the same side ( P > 0.05). Table 6 Comparison the various parameters of L1 and R1 L1 (N = 60) R1 (N = 60) t P L(mm) 115.72 ± 9.00 117.81 ± 10.59 -1.891 0.064 LE(mm) 8.21 ± 1.95 7.85 ± 2.07 1.728 0.089 LH(mm) 15.85 ± 3.84 15.40 ± 4.04 0.985 0.329 LI(mm) 83.78 ± 7.91 85.20 ± 8.91 -1.467 0.148 LP(mm) 27.30 ± 5.34 27.29 ± 3.63 0.003 0.997 LS(mm) 34.16 ± 6.14 34.06 ± 5.71 0.153 0.879 α(°) 38.33 ± 4.36 38.09 ± 3.44 0.599 0.552 β(°) 56.26 ± 7.71 55.14 ± 8.74 1.416 0.162 Note: * P < 0.05 indicates statistically significant difference Table 7 Comparison the various parameters of of L2 and R2 L2 (N = 60) R2 (N = 60) t P L(mm) 102.03 ± 9.87 104.98 ± 11.33 -1.732 0.088 LE(mm) 8.73 ± 1.78 8.51 ± 1.96 0.749 0.457 LH(mm) 26.53 ± 3.62 25.74 ± 3.51 1.833 0.072 LI(mm) 70.20 ± 14.31 72.78 ± 11.34 -1.134 0.262 LP(mm) 27.81 ± 5.16 30.48 ± 11.08 -1.719 0.091 LS(mm) 32.82 ± 5.59 32.64 ± 5.54 0.203 0.840 α(°) 44.96 ± 4.70 44.88 ± 4.34 0.156 0.877 β(°) 56.24 ± 9.29 55.35 ± 9.30 0.871 0.387 Note: * P < 0.05 indicates statistically significant difference Table 8 Comparison the various parameters of of L1 and L2 L1 (N = 60) L2 (N = 60) t P L(mm) 115.72 ± 9.00 95.56 ± 11.17 17.140 0.000* LE(mm) 8.21 ± 1.95 10.60 ± 3.08 -5.556 0.000* LH(mm) 15.85 ± 3.84 26.53 ± 3.62 29.509 0.000* LI(mm) 83.78 ± 7.91 62.87 ± 13.60 13.468 0.000* LP(mm) 27.30 ± 5.34 27.81 ± 5.16 -2.220 0.030* LS(mm) 34.16 ± 6.14 32.82 ± 5.59 1.752 0.047* α(°) 38.33 ± 4.36 46.05 ± 4.70 -16.200 0.000* β(°) 56.26 ± 7.71 57.24 ± 9.52 -2.074 0.042* Note: * P < 0.05 indicates statistically significant difference Table 9 Comparison the various parameters of of R1 and R2 R1 (N = 60) R2 (N = 60) t P L(mm) 117.81 ± 10.59 104.98 ± 11.34 13.614 0.000* LE(mm) 7.85 ± 2.07 8.51 ± 1.96 -3.042 0.004* LH(mm) 15.4 ± 4.04 25.74 ± 3.51 -24.396 0.000* LI(mm) 85.2 ± 8.91 72.78 ± 11.34 9.541 0.000* LP(mm) 27.29 ± 3.63 30.48 ± 11.08 -2.209 0.031* LS(mm) 34.06 ± 5.71 32.64 ± 5.54 2.394 0.020* α(°) 38.09 ± 3.44 44.88 ± 4.34 -15.447 0.000* β(°) 55.14 ± 8.74 55.35 ± 9.30 -0.348 0.729 Note: * P < 0.05 indicates statistically significant difference Regarding the measurement of the radius of the simulated screw trajectory, as shown in Table 10 , the radius of all simulated screw trajectories were greater than 4 mm, and the mean values were greater than 4.5 mm. No significant differences in the radius of any of the simulated screw trajectories were found between sexes or between entry point positions ( P > 0.05). Table 10 Comparison the various parameters of screw trajectory radius Men Women t P L1(mm) 4.78 ± 0.31 4.72 ± 0.39 0.734 0.466 L2(mm) 4.52 ± 0.4 4.55 ± 0.38 -0.329 0.743 R1(mm) 4.75 ± 0.31 4.62 ± 0.43 1.372 0.176 R2(mm) 4.48 ± 0.36 4.53 ± 0.39 -0.515 0.609 Note: * P < 0.05 indicates statistically significant difference R: Screw trajectory radius Discussion To our knowledge the free-hand dual S2AI technique for spinopelvic fixation in patients with deformity and undergoing scoliosis correction required revision has not been previously described in the literature[ 14 ]. Robotic-assisted nail placement can be safely and effectively performed in dual sacral-2 alar-iliac screw fixation, but this technology have yet to become common[ 15 ]. Relevant studies had shown that the rate of S2AI screw-related complications after ASD surgery were 10.8%[ 16 ] and 35%[ 17 ]. Tang et al indicate that dual S2AI screw fixation is a feasible technique in patients with severe kyphoscoliosis, providing satisfactory correction of coronal balance and sagittal alignment with few postoperative complications[ 18 ]. In corrective operation of deformities of the spine, especially in cases of severe deformity requiring complex revision require long-segment posterior fixation, the stability of the lumbosacral junction is crucial. It is largely dependent on the strength of pelvic fixation[ 19 ]. Instability of the lumbosacral junction may lead to pseudarthrosis and construct failure[ 20 ]. Although the instrumentation can be extended across to the lumbosacral, lumbosacral fixation still remains a difficult clinical challenge for spinal surgeons, especially in cases of complex revision and severe deformity[ 21 ]. In 2009, Sponsell et al.[ 6 , 7 ] reported the use of S2AI screws for pelvic fixation, which provides a distal fixation option for internal fixation in adults with degenerative scoliosis and kyphosis. It has achieved satisfactory clinical efficacies and has been widely used in recent years. However, in cases of complicated revision and severe deformity, a single S2AI as crew often cannot achieve ideal fixation. Paul J. Park[ 12 ] and Jamal N. Shillingford et al.[ 11 ] reported the application of dual S2AI screws for the correction and revision of severe deformities and achieved clinical successes. However, whether this technique is applicable in the Chinese adult population and whether it has general applicability have not yet been clearly stated. At present, no definitive study has explored three-dimensional measurement of the screw trajectory of dual S2AI screws on the same side in the Chinese adult population, and corresponding data guidance for the clinical application of this technique is lacking. In this study, we validated the use of ipsilateral dual S2AI screws in the Chinese adult population by collecting measurement data from three-dimensional models of patients, and measured relevant screw trajectory data, which had not been previously published. In patients with scoliosis, the normal relationships between parameters of sacropelvic and spinopelvic alignment are commonly altered. Therefore, it’s the bony landmarks of the pelvis not of the sacropelvic and spinopelvic that were chosen as references, which was not affected by the spinal deformity. To facilitate the installation of an internal fixation connecting rod, the entry point of the S2AI screw should be aligned with the starting points of S1 and L5 pedicle screws. The starting point of the S1 pedicle screw is the lower edge of the superior articular process of S1, which can be moved slightly outward without causing nerve injury[ 22 ]. Therefore, the lateral sacral crest of the S1 and S2 foramina was chosen as the reference for screw entry points[ 12 ]. The distance between the starting points was greater than 10 mm in all patients (Table 1 ). Therefore, we demonstrate that the outer edges of the sacral foramina at S1 and S2 of all patients could accommodate the end caps of two S2AI screws without causing screw placement failure due to interference of the end caps of the screws. Oue research, provide a basis for successful placement of two S2AI screws on the same side. The optimal screw trajectory for SAI screws is located in the iliac cancellous bone directly above the ischial notch. When the screw passes through the sacroiliac joint, both the iliac cancellous bone directly above the ischial notch and the cortical bone of the sacroiliac joint result in greater pullout strength[ 23 ] .The cortical bone during clinical application are rare, the cortical bone outside the screw trajectory of S2AI screws is surrounded by important neurovascular structures, in spite of few literature about S2AI screws significantly perforating the cortical bone during clinical application was reported [ 24 ]. In previous clinical applications of S2AI screws, clinicians were most concerned about the damage to the cortical bone of the greater sciatic notch, which could damage the sciatic nerve below the greater sciatic notch, the internal iliac artery and vein, and the posterior and posterosuperior supragluteal neurovascular bundles, injuries that often lead to more serious clinical consequences[ 13 , 25 , 26 ]. Compared with cranial L2 and R2 screws, L1 and R1 screws are closer to the greater sciatic notch and are thus more likely to cause damage to important tissues. Therefore, when simulating screw placement, we placed L1 or R1 first and then measured the distance from the top of the greater sciatic notch to the cross-section of the screw trajectory. Because the L2 and R2 screws are close to the upper end of the ilium, the important neurovascular injuries are less likely to occur. However, there is a thin area at the upper end of the ilium with a thickness less than 5 mm[ 27 ], therefore, screws should be placed as low as possible at this location, and thinner screws should be selected. The results showed that for the patients in this study, the simulated screw trajectories of all four screws did not interfere with or cross each other. Table 11 shows that the radii of the simulated L2 and R2 screw trajectories were smaller than those of the simulated L1 and R1 screw trajectories, which is consistent with the anatomical characteristics of ilium. Biomechanical and clinical results show that S2AI screws with a diameter less than 8 mm can break easily[ 28 ]. In the patients in the present study, the diameters of all simulated screw trajectories were greater than 8 mm, which meet clinical requirements and provide better biomechanical stability. Compared with conventional iliac screws, S2AI screws can reduce complications such as infection that caused by muscle stripping[ 29 ]. In this study, the measured distances from the entry points of the L1, L2, R1 and R2 screws to the median sagittal plane were 27.30 ± 5.34 mm, 27.81 ± 5.16 mm, 27.29 ± 3.63 mm and 30.48 ± 11.08 mm, respectively, and there was no statistically significant difference among the four simulated screw entry points, indicating that the entry points of the two screws on the same side can be located on the same axis to facilitate the installation of the connecting rod. Moreover, statistical analysis showed that the screw entry points were closer to the middle of sacrum than the screw entry points of the Galveston rod fixation and iliac screw techniques, thereby reducing soft tissue dissection and the incidence of deep infection. The use of traditional screws for sacroiliac joint fixation often leads to postoperative discomfort at the sacroiliac joint due to the stimulation of the sacroiliac joint by the threads, among other causes[ 30 ]. The S2AI screw shank is designed as a smooth rod to reduce stimulation of the sacroiliac joint by the threads. The results of the optimal screw trajectory measurement in the patients in this study showed that the average length L of the L1 screw trajectory was 115.72 ± 9.00 mm, and LS was 34.16 ± 6.14 mm; the average length L of the L2 screw trajectory was 102.03 ± 9.87 mm, and LS was 32.82 ± 5.59 mm; the average length L of the R1 screw trajectory was117.81 ± 10.59 mm, and LS was 34.06 ± 5.71 mm; and the average length L of the R2 screw trajectory 104.98 ± 11.33 mm, and LS was 32.64 ± 5.54 mm. For S2AI screws with a length greater than 80 mm, the length of the smooth rod was 43 mm. The LS length in the simulated screw trajectory of the four screws was much less than 43 mm. As the total length of the screw increases, the length of the smooth rod also increases, which can effectively avoid discomfort at the sacroiliac joint caused by the stimulation from the screw thread after internal fixation. This study has several limitations. Firstly, the study used the anatomical data of outpatients or emergency patients, some of whom suffered from hip degeneration, lumbar degeneration, and even hip fracture. Therefore, the data obtained in this study should not be considered as a representative of the healthy population. Nonetheless, this study provides some basic information about the use of dual S2AI screws. The second limitation of this study is that it was based on the ideal trajectory of ipsilateral dual S2AI screws in geometric space without considering about the factors such as biomechanics. In clinical applications, the fixation effect of the screws must be evaluated, followed by a corresponding biomechanical analysis. Thirdly, the study contained a relatively small number of patients with a large age range, and further studies with a larger sample may be necessary. Conclusion In this study, we show that placing two S2AI screws with a radius > 4 mm on the same side is feasible in the Chinese adult population, furthermore, in some patients, placing two S2AI screws with a radius > 5 mm on the same side is also feasible. In addition, preoperative three-dimensional reconstruction and screw placement simulation using Mimics can effectively simulate ipsilateral dual S2AI screw placement, assist preoperative planning, and guide precise placement of the screws during the operation. Ipsilateral dual S2AI screws can avoid the insufficient biomechanical stability caused by single screw and the internal fixation failure. Declarations Acknowledgements Not applicable. Author’s contributions Study conception and design were performed by Mengqi Xie, Chao Chen, Baoshan Xu, and Yu Zhao. Acquisition of data was conducted by Mengqi Xie, Zhi Wang, Dong Zhao, and Gang Liu. Analysis and interpretation of data were done by Xun Sun, Xiaoman Dong, and Shan Zhu. Drafting the manuscript was performed by Mengqi Xie and Chao Chen. Critical revision of manuscript was conducted by Xinlong Ma and Qiang Yang. All authors read and approved the final manuscript. Funding This study was supported by National Key R&D Program of China (2023YFC2416900). National Natural Science Foundation of China (82372419). Tianjin Science and Technology Plan Project “Unveiling and Directing” Major Project (21ZXJBSY00130). Ethics approval and consent to participate This study was approved by the Ethics Committee of Tianjin Hospital（2020136） and complied with the approved guidelines. The need for informed consent requirement was waived owing to the retrospective nature of the study. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests All the authors declare that they have no conflict of interest. Consent for publication Not applicable. References Moshirfar A, Rand FF, Sponseller PD, Parazin SJ, Khanna AJ, Kebaish KM, et al. Pelvic fixation in spine surgery. Historical overview, indications, biomechanical relevance, and current techniques. J Bone Joint Surg Am. 2005;87 Suppl 2:89-106. Allen BL, Jr., Ferguson RL. The Galveston technique of pelvic fixation with L-rod instrumentation of the spine. Spine (Phila Pa 1976). 1984;9(4):388-94. Tumialan LM, Mummaneni PV. Long-segment spinal fixation using pelvic screws. Neurosurgery. 2008;63(3 Suppl):183-90. Agulnick M, Cohen BR, Epstein NE. Reconstruction of Shattered Lumbo-Sacral Junction/Pelvis Utilizing Bilateral L4-Sacrum Fibula Strut Allograft And Double Iliac Screws Plus Routine Lumbar Pedicle Screw Fixation. Surg Neurol Int. 2020;11:335. Peelle MW, Lenke LG, Bridwell KH, Sides B. Comparison of pelvic fixation techniques in neuromuscular spinal deformity correction: Galveston rod versus iliac and lumbosacral screws. Spine (Phila Pa 1976). 2006;31(20):2392-8; discussion 9. O'Brien JR, Matteini L, Yu WD, Kebaish KM. Feasibility of minimally invasive sacropelvic fixation: percutaneous S2 alar iliac fixation. Spine (Phila Pa 1976). 2010;35(4):460-4. O'Brien JR, Yu WD, Bhatnagar R, Sponseller P, Kebaish KM. An anatomic study of the S2 iliac technique for lumbopelvic screw placement. Spine (Phila Pa 1976). 2009;34(12):E439-42. Ray WZ, Ravindra VM, Schmidt MH, Dailey AT. Stereotactic navigation with the O-arm for placement of S-2 alar iliac screws in pelvic lumbar fixation. J Neurosurg Spine. 2013;18(5):490-5. Wu AM, Chi YL, Ni WF, Huang YX. The feasibility and radiological features of sacral alar iliac fixation in an adult population: a 3D imaging study. PeerJ. 2016;4:e1587. Ilyas H, Place H, Puryear A. A Comparison of Early Clinical and Radiographic Complications of Iliac Screw Fixation Versus S2 Alar Iliac (S2AI) Fixation in the Adult and Pediatric Populations. J Spinal Disord Tech. 2015;28(4):E199-205. Fang T, Russo GS, Schroeder GD, Kepler CK. The Accurate Free-hand Placement of S2 Alar Iliac (S2AI) Screw. Clin Spine Surg. 2020;33(3):102-3. Park PJ, Lin JD, Makhni MC, Cerpa M, Lehman RA, Lenke LG. Dual S2 Alar-Iliac Screw Technique With a Multirod Construct Across the Lumbosacral Junction: Obtaining Adequate Stability at the Lumbosacral Junction in Spinal Deformity Surgery. Neurospine. 2020;17(2):466-70. Abdul-Jabbar A, Yilmaz E, Iwanaga J, Tawfik T, O'Lynnger TM, Schildhauer TA, et al. Neurovascular Relationships of S2AI Screw Placement: Anatomic Study. World Neurosurg. 2018;116:e108-e12. Huang W, Xu L, Cai W, Cheng M, Sun Z, Wang S, et al. Freehand S2‐Alar‐Iliac Screw Placement Technique in Lumbosacral Spinal Tumors: A Preliminary Study. Orthopaedic Surgery. 2022;14(9):2195-202. Hiyama A, Ukai T, Ogasawara S, Tanaka T, Watanabe M. Minimally Invasive 360° Fusion Using a Combination of INFIX and Minimally Invasive Spinopelvic Fixation by Intraoperative Computed Tomography Navigation for Unstable Pelvic Ring Fracture: A Technical Note. Orthopaedic Surgery. 2023;15(5):1405-13. Ha AS, Hong DY, Luzzi AJ, Coury JR, Cerpa M, Sardar Z, et al. Minimum 2-Year Analysis of S2-Alar-Iliac Screw Fixation for Adult Spinal Deformity. Global Spine J. 2022;12(8):1640-6. Guler UO, Cetin E, Yaman O, Pellise F, Casademut AV, Sabat MD, et al. Sacropelvic fixation in adult spinal deformity (ASD); a very high rate of mechanical failure. Eur Spine J. 2015;24(5):1085-91. Tang Z, Hu Z, Zhu Z, Qiao J, Mao S, Ling C, et al. The Utilization of Dual Second Sacral Alar‐Iliac Screws for Spinopelvic Fixation in Patients with Severe Kyphoscoliosis. Orthopaedic Surgery. 2022;14(7):1457-68. Liu Zj, Hu Yc, Tian W, Jin X, Qi Ht, Sun Yx, et al. Robot‐Aided Minimally Invasive Lumbopelvic Fixation in Treatment of Traumatic Spinopelvic Dissociation. Orthopaedic Surgery. 2021;13(2):563-72. Weistroffer JK, Perra JH, Lonstein JE, Schwender JD, Garvey TA, Transfeldt EE, et al. Complications in long fusions to the sacrum for adult scoliosis: minimum five-year analysis of fifty patients. Spine (Phila Pa 1976). 2008;33(13):1478-83. Cunningham BW, Sefter JC, Hu N, Kim SW, Bridwell KH, McAfee PC. Biomechanical comparison of iliac screws versus interbody femoral ring allograft on lumbosacral kinematics and sacral screw strain. Spine (Phila Pa 1976). 2010;35(6):E198-205. Kubaszewski L, Nowakowski A, Kaczmarczyk J. Evidence-based support for S1 transpedicular screw entry point modification. J Orthop Surg Res. 2014;9:22. Mattei TA, Fassett DR. Combined S-1 and S-2 sacral alar-iliac screws as a salvage technique for pelvic fixation after pseudarthrosis and lumbosacropelvic instability: technical note. J Neurosurg Spine. 2013;19(3):321-30. Garin A, Abara S, Herrera C, Acuna I, Cancino J, Bettancourt S, et al. Delayed lower extremity paresis following iliosacral screws: Atypical complication and treatment. Trauma Case Rep. 2021;31:100380. Hasan MY, Liu G, Wong HK, Tan JH. Postoperative complications of S2AI versus iliac screw in spinopelvic fixation: a meta-analysis and recent trends review. Spine J. 2020;20(6):964-72. Marmor M, Lynch T, Matityahu A. Superior gluteal artery injury during iliosacral screw placement due to aberrant anatomy. Orthopedics. 2010;33(2):117-20. Liu F, Yang Y, Wen C, Guo L, Wang A, Huang W, et al. Morphometric measurement and applicable feature analysis of sacral alar-iliac screw fixation using forward engineering. Arch Orthop Trauma Surg. 2020;140(2):177-86. Jain A, Kebaish KM, Sponseller PD. Sacral-Alar-Iliac Fixation in Pediatric Deformity: Radiographic Outcomes and Complications. Spine Deform. 2016;4(3):225-9. Phillips JH, Gutheil JP, Knapp DR, Jr. Iliac screw fixation in neuromuscular scoliosis. Spine (Phila Pa 1976). 2007;32(14):1566-70. Yoshihara H. Sacroiliac joint pain after lumbar/lumbosacral fusion: current knowledge. Eur Spine J. 2012;21(9):1788-96. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. 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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-3927343","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":271568556,"identity":"c02f1e23-b8bc-43f4-b4e8-f5ec702c5cfc","order_by":0,"name":"Mengqi Xie","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mengqi","middleName":"","lastName":"Xie","suffix":""},{"id":271568557,"identity":"0e551669-d183-42d5-a126-6e898218e2b9","order_by":1,"name":"Chao Chen","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chao","middleName":"","lastName":"Chen","suffix":""},{"id":271568558,"identity":"458d66e2-8094-419e-8120-74dc4d04315a","order_by":2,"name":"Xun Sun","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xun","middleName":"","lastName":"Sun","suffix":""},{"id":271568559,"identity":"a74c2d09-b124-4824-aa44-4c6b6cc65c4d","order_by":3,"name":"Xiaoman Dong","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xiaoman","middleName":"","lastName":"Dong","suffix":""},{"id":271568560,"identity":"84d703c7-267e-4fd1-b2d5-8637451d7940","order_by":4,"name":"Zhi Wang","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Zhi","middleName":"","lastName":"Wang","suffix":""},{"id":271568561,"identity":"49dfe799-56c5-4d69-a99f-fbaea70c1fd8","order_by":5,"name":"Dong Zhao","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Dong","middleName":"","lastName":"Zhao","suffix":""},{"id":271568562,"identity":"3571f235-bd6b-4725-bccd-5a372d4c482e","order_by":6,"name":"Gang Liu","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Gang","middleName":"","lastName":"Liu","suffix":""},{"id":271568563,"identity":"9422ebf0-3ec1-4c6a-914d-10e06a52c033","order_by":7,"name":"Shan Zhu","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Shan","middleName":"","lastName":"Zhu","suffix":""},{"id":271568564,"identity":"4457b47f-071b-4aa6-a5ad-0a38cd68fc39","order_by":8,"name":"Baoshan Xu","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Baoshan","middleName":"","lastName":"Xu","suffix":""},{"id":271568565,"identity":"71a1fd9c-1732-4755-ab25-ec8596e7ba25","order_by":9,"name":"Yu Zhao","email":"","orcid":"","institution":"Peking Union Medical College Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Zhao","suffix":""},{"id":271568566,"identity":"bc7e1897-2afb-468a-ac3c-6e8f7f9ad8fa","order_by":10,"name":"Xinlong Ma","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xinlong","middleName":"","lastName":"Ma","suffix":""},{"id":271568567,"identity":"bf2d88e3-f383-4833-b6cb-4b973c3f64a4","order_by":11,"name":"Qiang Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIiWNgGAWjYNACAyBmZj74IKFCQo6feC3sbMkGH85YGEs2EG0TP4+Z5My2isQNhLQYHD97+MWbArs8eWceY2PeeRKMGxiYHz66gU/Lmbw0yzkGycWGh9kKH/Nuk2A2Z2AzNs7Bp+VAjpkxjwFz4sZm5s3GQC1slg08bNJ4tZx/A9JSD9TCYCbNO0eCx+AAIS03cowf8xgcTpzPzAL0foOEBEEtkjfemDHOMTieuIEZFMjHJAwkmwn4he98jvGHN3+qE+f3HwZGZU1dfT9788PH+LQoHGBgk+ABhwNMiBmPchCQb2Bg/sADYYyCUTAKRsEowA4A5MNM739Uc8wAAAAASUVORK5CYII=","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":true,"prefix":"","firstName":"Qiang","middleName":"","lastName":"Yang","suffix":""}],"badges":[],"createdAt":"2024-02-04 11:14:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3927343/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3927343/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":50926906,"identity":"d57b035f-3203-4e20-8aa3-3af5dbf8cac2","added_by":"auto","created_at":"2024-02-09 17:12:59","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1905660,"visible":true,"origin":"","legend":"\u003cp\u003ethree-dimensional reconstruction of the pelvis and the entry point of the screws\u003c/p\u003e\n\u003cp\u003eA. The sagittal plane(red) bisected the pelvis, while the coronal plane(blue) passed through the anterior superior iliac spine and the anterior margin of the pubic symphysis and was perpendicular to the sagittal plane.\u003c/p\u003e\n\u003cp\u003eB. The bone bridge between the outer edges of the sacral foramina at S1 and S2 was trisected, the entry point of the first screw was located in the lower third and defined as L1 or R1, and the entry point of the second screw was in the upper third and defined as L2 or R2.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-3927343/v1/8a740549aa72d886864e01ec.png"},{"id":50926904,"identity":"d437955e-8ced-49b2-81e9-03be14aa0cb8","added_by":"auto","created_at":"2024-02-09 17:12:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2105819,"visible":true,"origin":"","legend":"\u003cp\u003eThe screw placement simulation was performed by adjusting the screw position and diameter\u003c/p\u003e\n\u003cp\u003eA. Opaque mode(2A) was used to observe whether any simulated screw trajectory penetrated the cortical bone of the pelvis.\u003c/p\u003e\n\u003cp\u003eB. Transparent mode(2B) was used to observe whether the simulated screw trajectories crossed or interfered with each other.\u003c/p\u003e\n\u003cp\u003eC. The cross section(2C red) of each screw trajectory passed through the centerline of the cylinder of the screw trajectory and was perpendicular to the sagittal plane.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-3927343/v1/8b9c5903009508970ece8b9e.png"},{"id":50926905,"identity":"ec116c18-382a-4503-9672-d6b7ddd51ff2","added_by":"auto","created_at":"2024-02-09 17:12:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1716373,"visible":true,"origin":"","legend":"\u003cp\u003eThe ideal trajectory of each simulated screw trajectory\u003c/p\u003e\n\u003cp\u003eA. Abduction angle, α: the angle between the optimal screw trajectory and the median sagittal plane\u003c/p\u003e\n\u003cp\u003eB. Caudal deviation angle, β: the angle between the optimal screw trajectory and the coronal plane\u003c/p\u003e\n\u003cp\u003eC. AB：Screw length, L: the distance between two points, that is, the total length of the simulated trajectory (the distance from the optimal entry point A to the exit point B)\u003c/p\u003e\n\u003cp\u003eAC: Length in sacrum, LS: the length of the optimal screw trajectory in the sacrum;\u003c/p\u003e\n\u003cp\u003eBC: Length in ilium, LI: the length of the optimal screw trajectory in the ilium;\u003c/p\u003e\n\u003cp\u003eAP: the shortest length from the screw entry point to the median sagittal plane（LP）;\u003c/p\u003e\n\u003cp\u003eD. LH: the shortest distance from the greater sciatic notch to the cross-section of the screw trajector\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-3927343/v1/e20824aa363fad3cc3e08d67.png"},{"id":50956855,"identity":"67bccba5-2c88-4a96-b2ed-5554d01235e9","added_by":"auto","created_at":"2024-02-10 19:08:23","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2417621,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3927343/v1/9e5f5174-a9ce-43f2-850a-eb0336f79523.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Radiographic Parameters and feasibility analysis of dual sacral-2 alar-iliac screw fixation using three-dimensional digital technology","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLong-level fusion across the lumbosacral junction and strong spin-pelvic fixation are frequently required in complex spinal deformity and tumor surgery. The spin-pelvic fixation technique has provided a new option for long-level spinal fixation and fusion (comprising 5 or more vertebral bodies), as well as the treatment of severe spondylolisthesis, lumbar deformity, pelvic obliquity, severe osteoporosis and lumbosacral fixation after tumor development and infection[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The Galveston technique had been widely used in spin-pelvic fixation technique since introduced by Allen and Ferguson in1984[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Iliac screws are safe during insertion and associated with low rates of long-term implant complications. This led some surgeons to abandon the Galveston technique in favor of Iliac screws[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Sacral and lumbar screw fixation may contribute to spin-pelvic construct stability, but need additional Iliac screws[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. In the above techniques, either a large amount of soft tissue is stripped or the internal fixations are difficult to install, owing the need for separate connectors[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTherefore, it would be of great significance to find a safe and effective solution for spin-pelvic fixation. Sponsell et al. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]first reported the application of sacral-2 alar-iliac (S2AI) screws for pelvic fixation in 2009.This method provides a distal fixation plan for internal fixation in adults with degenerative scoliosis and kyphosis. It has achieved good clinical results and has been widely used in recent years. S2AI screw fixation technique can reduce the range of soft tissue stripping[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], and it has a higher fixation strength when the screw passing through the three layers of dense cortical bone of the sacroiliac joint[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Furthermore, any lateral connector is not required during the operation, this can help reduce the difficulty of surgery and bring down the risk of loosening and pulling out of the internal fixation. In addition, due to the lower risk of reoperation, the probability of secondary injury and infection are reduced. Consequently, the application of S2AI screws is becoming increasingly common[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The placement method of S2AI screws has obvious advantages in fixation and preventing screw protrusion, however, due to the complex anatomical structure of the sacropelvic, the proximity of screw placement sites to important anatomical structures, and large individual differences[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] comprise the main challenges of S2AI screw placement at present. Additionally, for some patients with complex revisions or severe deformities, a single S2AI screw often cannot provide strong adequate biomechanical stability. Therefore, stronger spin-pelvic fixation may be required under some circumstances. Although there are many studies on the screw trajectory of single S2AI screw placement, there are few reports about the application of dual S2AI screws[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], and the specific parameters of the trajectory of dual S2AI screws have not been described. Dual S2 Alar-Iliac Screw Technique (Dual S2AI) was first reported by Lenke LG et al.[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] in 2020, as part of long spinal constructs in patients with significant adult spinal deformity, it can provide a safe and effective long-term correction and clinical success. However further study is necessary to demonstrate this thesis.\u003c/p\u003e \u003cp\u003eHowever, to our knowledge, no conclusive study is available on three-dimensional measurement and the simulation of screw trajectories in the clinical application of unilateral dual S2AI screws. In previous clinical applications of S2AI screws, clinicians were mostly concerned about the damage to the cortical bone of the greater sciatic notch, which could damage the sciatic nerve below the greater sciatic notch, the internal iliac artery and vein, and the posterior and posterosuperior supragluteal neurovascular bundles, injuries that often lead to more serious clinical consequences[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Therefore, a elaborate start point and trajectory is crucial to ensure patient safety in the placement of unilateral dual S2AI screws.\u003c/p\u003e \u003cp\u003eTo sum up, the aims of our study are (1) to investigate the feasibility of unilateral dual S2AI screws in the Chinese adult population with Mimics software, (2) to simulate screw trajectories and collect three-dimensional measurement data, analysis the differences in distance parameters, radius and angle between men and women in the same location, as well as the differences between different sides at the same level, (3) to provide accurate reference data for the clinical application of this technique.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy subjects\u003c/h2\u003e \u003cp\u003eIn this study, the three-dimensional pelvic computed tomography (CT) scans of 60 adult patients were randomly selected from patients undergoing three-dimensional pelvic CT scans at our hospital from January 2020 to June 2020. Three-dimensional pelvic CT scans should include the sacrum, coccyx, and hip bones. The exclusion criteria were as follows: I. patients with a history metabolic bone disease, Ⅱ. long-term use of hormones, Ⅲ.sacral tumors and infections, Ⅳ. pelvic deformities, Ⅴ. fractures and hip dislocations, Ⅵ. lumbosacral pelvic trauma or surgery.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eImaging reconstruction\u003c/h2\u003e \u003cp\u003eThe above CT scans (in DICOM format) were imported into Mimics 20.0 software (Materialise, Belgium; version 20.0) for three-dimensional reconstruction of the pelvis (sacrum and hip). Sagittal plane and coronal plane were determined on the reconstructed pelvis image for calculation of the orientation of each screw trajectory (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). To avoid bias brought by the deformity of pelvic tilt rotation and torsion, the sagittal plane bisected the pelvis, while the coronal plane passed through the anterior superior iliac spine and the anterior margin of the pubic symphysis and was perpendicular to the sagittal plane.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eSimulation and analysis of L1 L2 R1 R2 screw channels\u003c/h2\u003e \u003cp\u003eThe entry points of the four S2AI screws were determined on the reconstructed three-dimensional images[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The lateral sacral crest between the S1 and S2 foramina in the mediolateral direction was trisected, the entry point of the first screw was located in the lower third and defined as L1 or R1, and the the second screw was in the upper third and defined as L2 or R2 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). Because the radius of the tail end of an S2AI screw is 5 mm, if the measured distance between the entry points of two screws on the same side is greater than 10 mm, screw placement can be completed. A cylinder with a radius of 5 mm was selected to simulate screw placement. If screw placement based on a cylinder with a 5 mm radius failed, then a cylinder with a radius of 4.5 mm or 4 mm was selected. Screw placement simulation started at L1 or R1, and the coordinates of L1 or R1 were used to simulate one end of the screw. The screw placement simulation was performed by adjusting the screw position and diameter, and the same method was used to complete simulated placement of all four screws (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA/B). Ensuring simulated screw trajectory did not penetrate the cortical bone of the pelvis or interfered with each other. The cross section of each screw trajectory passed through the centerline of the cylinder of the screw trajectory and was perpendicular to the sagittal plane (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eData metrics\u003c/h2\u003e \u003cp\u003eThe ideal trajectory of each simulated screw trajectory was as follows (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e): Ⅰ. Screw length(L): the distance between two points, that is, the total length of the simulated trajectory (the distance from the optimal entry point to the exit point); Ⅱ. Screw trajectory radius(R): the radius of the optimal cylinder for screw trajectory simulation; Ⅲ. LE: the shortest distance from the edge of the ipsilateral sacral foramen to the simulated screw trajectory; Ⅳ. Length in sacrum(LS): the length of the optimal screw trajectory in the sacrum; Ⅴ. Length in ilium(LI): the length of the optimal screw trajectory in the ilium; Ⅵ. LP: the shortest length from the screw entry point to the median sagittal plane; Ⅶ. LH: the shortest distance from the greater sciatic notch to the cross-section angle between the screw trajectory; Ⅷ. Abduction angle (α): the angle between the optimal screw trajectory and the median sagittal plane; Ⅸ. Caudal deviation angle(β): the angle between the optimal screw trajectory and the coronal plane. All CT data sets were measured by a consultant radiologist and a spine surgeon independently. A descriptive study of the variables was carried out. The concordance between the different scores was analyzed through the kappa concordance index.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using IBM SPSS Statistics for Windows (Version 21.0; IBM, Armonk, NY, USA). All parameters are expressed as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. To test the significance of the observed differences between men and women, an independent-samples t-test was used. To test the significance of the observed differences in different screw trajectories, a paired-samples t-test was employed. \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 60 patients (30 males and 30 females aged 25\u0026ndash;86 years, with a mean age of 61.6 years) were enrolled in this study. Their ages ranged from 25 to 86 years, with an average age of 62.03\u0026thinsp;\u0026plusmn;\u0026thinsp;12.91 years. The results of the normality test showed that the age distribution conformed to a normal distribution (Kolmogorov-Smirnov Z\u0026thinsp;=\u0026thinsp;1.323, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.060). Unilateral dual S2AI screws could be successfully simulated in all patients in this group using Mimics three-dimensional reconstruction software, and the relevant data of the optimal screw trajectories could be successfully measured.\u003c/p\u003e \u003cp\u003eThe measured distance between the entry points of two screws on the same side was greater than 10 mm in all patients. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the mean distances were all greater than 11.5 mm in each group, and no significant difference was found between men and women on the left side, while a significant difference between men and women was identified on the right side. The results provide a basis for accommodating two S2AI screw tails in the screw entry point area. No significantly different in the distance between entry points of the two screws was identified between different sides(\u003cem\u003eP\u003c/em\u003e \u0026gt;0.05). According to the consistency test, the Kappa consistency test value of radiologist and spine surgeon results was 0.821, indicating a general consistency.\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\u003eThe measured distance between the entry points of two screws\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=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eScrew entry points (L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e11.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e-0.061\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.952\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e11.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87\u003c/p\u003e \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\u003eScrew entry points (R)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e11.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e-2.493\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.016 \u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e11.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e \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 \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eNote: *P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the parameters of the screw at L1 between men and women\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMen (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWomen (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e115.16\u0026thinsp;\u0026plusmn;\u0026thinsp;9.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e114.62\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.219\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.827\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLE(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e11.47\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e10.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.795\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.430\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLH(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e17.52\u0026thinsp;\u0026plusmn;\u0026thinsp;3.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e14.18\u0026thinsp;\u0026plusmn;\u0026thinsp;2.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.706\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLI(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e80.36\u0026thinsp;\u0026plusmn;\u0026thinsp;7.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e81.16\u0026thinsp;\u0026plusmn;\u0026thinsp;9.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.367\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.715\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLP(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e26.01\u0026thinsp;\u0026plusmn;\u0026thinsp;5.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e28.58\u0026thinsp;\u0026plusmn;\u0026thinsp;4.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.910\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.061\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLS(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e34.89\u0026thinsp;\u0026plusmn;\u0026thinsp;6.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e33.43\u0026thinsp;\u0026plusmn;\u0026thinsp;6.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.920\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.362\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e38.68\u0026thinsp;\u0026plusmn;\u0026thinsp;4.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e37.98\u0026thinsp;\u0026plusmn;\u0026thinsp;4.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.621\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.537\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e56.16\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e56.37\u0026thinsp;\u0026plusmn;\u0026thinsp;9.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.103\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.918\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eL: Screw length, LE: the shortest distance from the edge of the ipsilateral sacral foramen to the simulated screw trajectory, LS: Length in sacrum, LI: Length in ilium, LP: the shortest length from the screw entry point to the median sagittal plane, LH: the shortest distance from the greater sciatic notch to the cross-section angle between the screw trajectory,α:Abduction angle, β:Caudal deviation angle\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eDigital measurements of L1 screw trajectory\u003c/h2\u003e \u003cp\u003eBased on the simulated trajectory of the L1 screw, the average α angle on the men and women respectively was 38.68\u0026thinsp;\u0026plusmn;\u0026thinsp;4.65\u0026deg;and 37.98\u0026thinsp;\u0026plusmn;\u0026thinsp;4.11\u0026deg;. The average β angle on the men and women respectively was 56.16\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u0026deg;and 56.37\u0026thinsp;\u0026plusmn;\u0026thinsp;9.22\u0026deg;. With respect to distance parameters, the average total length of the simulated trajectory was approximately 115.16\u0026thinsp;\u0026plusmn;\u0026thinsp;9.36 mm in males and 114.62\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7 mm in females (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). No significant difference in L, LE, LI, LP, LS, α or β angles was identified between sexes (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). LH values were 17.52\u0026thinsp;\u0026plusmn;\u0026thinsp;3.96 in men and 14.18\u0026thinsp;\u0026plusmn;\u0026thinsp;2.92 in women; therefore, the distance from the greater sciatic notch to the cross-section of the L1 screw trajectory was significantly longer in men than in women (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001)(Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the parameters of the screw at L2 between men and women\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMen (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWomen (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e102.20\u0026thinsp;\u0026plusmn;\u0026thinsp;8.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e101.86\u0026thinsp;\u0026plusmn;\u0026thinsp;11.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.132\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.895\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLE (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.34\u0026thinsp;\u0026plusmn;\u0026thinsp;1.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e9.12\u0026thinsp;\u0026plusmn;\u0026thinsp;1.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.714\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.092\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLH (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e28.19\u0026thinsp;\u0026plusmn;\u0026thinsp;2.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e25.54\u0026thinsp;\u0026plusmn;\u0026thinsp;4.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.964\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.004 *\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLI (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e74.84\u0026thinsp;\u0026plusmn;\u0026thinsp;14.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e65.56\u0026thinsp;\u0026plusmn;\u0026thinsp;12.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.635\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.011*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLP (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e27.14\u0026thinsp;\u0026plusmn;\u0026thinsp;5.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e28.48\u0026thinsp;\u0026plusmn;\u0026thinsp;4.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.317\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLS (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e31.43\u0026thinsp;\u0026plusmn;\u0026thinsp;5.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e34.20\u0026thinsp;\u0026plusmn;\u0026thinsp;5.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.962\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.055\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e45.65\u0026thinsp;\u0026plusmn;\u0026thinsp;3.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e44.28\u0026thinsp;\u0026plusmn;\u0026thinsp;4.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.287\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.203\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e56.15\u0026thinsp;\u0026plusmn;\u0026thinsp;7.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e56.34\u0026thinsp;\u0026plusmn;\u0026thinsp;10.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.077\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.939\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eDigital measurements of L2 screw trajectory\u003c/h2\u003e \u003cp\u003eBased on the simulated trajectory of the L2 screw, the average α angle on the men and women respectively was 45.65\u0026thinsp;\u0026plusmn;\u0026thinsp;3.82\u0026deg;and 44.28\u0026thinsp;\u0026plusmn;\u0026thinsp;4.40\u0026deg;. The average β angle on the men and women respectively was 56.15\u0026thinsp;\u0026plusmn;\u0026thinsp;7.63\u0026deg;and 56.34\u0026thinsp;\u0026plusmn;\u0026thinsp;10.83\u0026deg;. With respect to distance parameters, the average total length of the simulated trajectory was approximately 102.20\u0026thinsp;\u0026plusmn;\u0026thinsp;8.66 mm in males and 101.86\u0026thinsp;\u0026plusmn;\u0026thinsp;11.11 mm in females (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). No significant difference in L, LE, LP, LS, α or β angles was found between sexes (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). LH values were 28.19\u0026thinsp;\u0026plusmn;\u0026thinsp;2.58 in men and 25.54\u0026thinsp;\u0026plusmn;\u0026thinsp;4.15 in women; therefore, the distance from the greater sciatic notch to the cross-section of the L2 screw trajectory was significantly longer in men than in women (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.005). LI values were 74.84\u0026thinsp;\u0026plusmn;\u0026thinsp;14.95 in men and 65.56\u0026thinsp;\u0026plusmn;\u0026thinsp;12.20 in women; therefore, the simulated screw trajectory for L2 was significantly longer in the iliac bones of men than in those of women (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eDigital measurements of R1 screw trajectory\u003c/h2\u003e \u003cp\u003eBased on the simulated trajectory of the R1 screw, the average α angle on the men and women respectively was 38.43\u0026thinsp;\u0026plusmn;\u0026thinsp;3.37\u0026deg;and 37.74\u0026thinsp;\u0026plusmn;\u0026thinsp;3.53\u0026deg;. The average β angle on the men and women respectively was 53.10\u0026thinsp;\u0026plusmn;\u0026thinsp;7.81\u0026deg;and 57.17\u0026thinsp;\u0026plusmn;\u0026thinsp;9.26\u0026deg;. With respect to distance parameters, the average total length of the simulated trajectory was approximately 116.49\u0026thinsp;\u0026plusmn;\u0026thinsp;11.69 mm in males and 119.12\u0026thinsp;\u0026plusmn;\u0026thinsp;9.38 mm in females (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). No significant difference in L, LE, LI, LP, LS, α and β angles was found between sexes (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). LH values were 16.09\u0026thinsp;\u0026plusmn;\u0026thinsp;4.08 in men and 14.71\u0026thinsp;\u0026plusmn;\u0026thinsp;3.94 in women; therefore, the distance from the greater sciatic notch to the cross-section of the R1 screw trajectory was significantly longer in men than in women (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the parameters of the screw at R1 between men and women\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMen (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWomen (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e116.49\u0026thinsp;\u0026plusmn;\u0026thinsp;11.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e119.12\u0026thinsp;\u0026plusmn;\u0026thinsp;9.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.963\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.340\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLE(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e7.68\u0026thinsp;\u0026plusmn;\u0026thinsp;1.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.02\u0026thinsp;\u0026plusmn;\u0026thinsp;2.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.620\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.538\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLH(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e16.09\u0026thinsp;\u0026plusmn;\u0026thinsp;4.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e14.71\u0026thinsp;\u0026plusmn;\u0026thinsp;3.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.339\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.029*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLI(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e83.48\u0026thinsp;\u0026plusmn;\u0026thinsp;8.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e86.93\u0026thinsp;\u0026plusmn;\u0026thinsp;9.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.515\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.135\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLP(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e26.48\u0026thinsp;\u0026plusmn;\u0026thinsp;2.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e28.10\u0026thinsp;\u0026plusmn;\u0026thinsp;4.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.759\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.085\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLS(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e34.55\u0026thinsp;\u0026plusmn;\u0026thinsp;6.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e33.56\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.672\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.504\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e38.43\u0026thinsp;\u0026plusmn;\u0026thinsp;3.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e37.74\u0026thinsp;\u0026plusmn;\u0026thinsp;3.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.771\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.444\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e53.10\u0026thinsp;\u0026plusmn;\u0026thinsp;7.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e57.17\u0026thinsp;\u0026plusmn;\u0026thinsp;9.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.838\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.071\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eDigital measurements of R2 screw trajectory\u003c/h2\u003e \u003cp\u003eBased on the simulated trajectory of the R2 screw, the average α angle on the men and women respectively was 45.89\u0026thinsp;\u0026plusmn;\u0026thinsp;3.48\u0026deg;and 43.87\u0026thinsp;\u0026plusmn;\u0026thinsp;4.91\u0026deg;. The average β angle on the men and women respectively was 55.37\u0026thinsp;\u0026plusmn;\u0026thinsp;7.96\u0026deg;and 55.34\u0026thinsp;\u0026plusmn;\u0026thinsp;10.62\u0026deg;. With respect to distance parameters, the average total length of the simulated trajectory was approximately 102.87\u0026thinsp;\u0026plusmn;\u0026thinsp;10.95 mm in males and 107.09\u0026thinsp;\u0026plusmn;\u0026thinsp;11.51 mm in females (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). No significant difference in L, LE, LP, LS, α and β angles between sexes (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). LH values were 26.90\u0026thinsp;\u0026plusmn;\u0026thinsp;3.76 in men and 24.59\u0026thinsp;\u0026plusmn;\u0026thinsp;2.85 in women; therefore, a significant difference between sexes was noted (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The LI values were 68.72\u0026thinsp;\u0026plusmn;\u0026thinsp;11.70 in men and 76.84\u0026thinsp;\u0026plusmn;\u0026thinsp;9.52 in women; therefore, the simulated screw trajectory for R2 was longer in the iliac bones of men than in those of women (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of various parameters at the R2 position between men and women\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMen (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWomen (n\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e102.87\u0026thinsp;\u0026plusmn;\u0026thinsp;10.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e107.09\u0026thinsp;\u0026plusmn;\u0026thinsp;11.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.454\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.151\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLE(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.41\u0026thinsp;\u0026plusmn;\u0026thinsp;2.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.62\u0026thinsp;\u0026plusmn;\u0026thinsp;1.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.420\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.676\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLH(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e26.90\u0026thinsp;\u0026plusmn;\u0026thinsp;3.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e24.59\u0026thinsp;\u0026plusmn;\u0026thinsp;2.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.683\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.009*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLI(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e68.72\u0026thinsp;\u0026plusmn;\u0026thinsp;11.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e76.84\u0026thinsp;\u0026plusmn;\u0026thinsp;9.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-2.950\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.005*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLP(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e27.74\u0026thinsp;\u0026plusmn;\u0026thinsp;2.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e33.22\u0026thinsp;\u0026plusmn;\u0026thinsp;15.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.965\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.058\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLS(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e33.16\u0026thinsp;\u0026plusmn;\u0026thinsp;6.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e32.13\u0026thinsp;\u0026plusmn;\u0026thinsp;4.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.714\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.478\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e45.89\u0026thinsp;\u0026plusmn;\u0026thinsp;3.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e43.87\u0026thinsp;\u0026plusmn;\u0026thinsp;4.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.830\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.072\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e55.37\u0026thinsp;\u0026plusmn;\u0026thinsp;7.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e55.34\u0026thinsp;\u0026plusmn;\u0026thinsp;10.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.990\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eNext, the left and right screw trajectories were compared. Tables\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and \u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e compare the measured parameters of the screws on different sides. The comparisons between L1 and R1 and between L2 and R2 showed no statistical differences for any of the measured items (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Tables\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e and \u003cspan refid=\"Tab9\" class=\"InternalRef\"\u003e9\u003c/span\u003e compare the two screw trajectories on the same side. Statistical differences were observed between the two S2AI screw trajectories on the same side (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison the various parameters of L1 and R1\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eL1 (N\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR1 (N\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e115.72\u0026thinsp;\u0026plusmn;\u0026thinsp;9.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e117.81\u0026thinsp;\u0026plusmn;\u0026thinsp;10.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.891\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.064\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLE(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.21\u0026thinsp;\u0026plusmn;\u0026thinsp;1.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e7.85\u0026thinsp;\u0026plusmn;\u0026thinsp;2.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.728\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.089\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLH(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e15.85\u0026thinsp;\u0026plusmn;\u0026thinsp;3.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e15.40\u0026thinsp;\u0026plusmn;\u0026thinsp;4.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.985\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.329\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLI(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e83.78\u0026thinsp;\u0026plusmn;\u0026thinsp;7.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e85.20\u0026thinsp;\u0026plusmn;\u0026thinsp;8.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.467\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.148\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLP(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e27.30\u0026thinsp;\u0026plusmn;\u0026thinsp;5.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e27.29\u0026thinsp;\u0026plusmn;\u0026thinsp;3.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.997\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLS(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e34.16\u0026thinsp;\u0026plusmn;\u0026thinsp;6.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e34.06\u0026thinsp;\u0026plusmn;\u0026thinsp;5.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.153\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.879\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e38.33\u0026thinsp;\u0026plusmn;\u0026thinsp;4.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e38.09\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.599\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.552\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e56.26\u0026thinsp;\u0026plusmn;\u0026thinsp;7.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e55.14\u0026thinsp;\u0026plusmn;\u0026thinsp;8.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.416\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.162\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison the various parameters of of L2 and R2\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eL2 (N\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR2 (N\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e102.03\u0026thinsp;\u0026plusmn;\u0026thinsp;9.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e104.98\u0026thinsp;\u0026plusmn;\u0026thinsp;11.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.732\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.088\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLE(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.73\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.749\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.457\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLH(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e26.53\u0026thinsp;\u0026plusmn;\u0026thinsp;3.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e25.74\u0026thinsp;\u0026plusmn;\u0026thinsp;3.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.833\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.072\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLI(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e70.20\u0026thinsp;\u0026plusmn;\u0026thinsp;14.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e72.78\u0026thinsp;\u0026plusmn;\u0026thinsp;11.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.134\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.262\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLP(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e27.81\u0026thinsp;\u0026plusmn;\u0026thinsp;5.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e30.48\u0026thinsp;\u0026plusmn;\u0026thinsp;11.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-1.719\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.091\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLS(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e32.82\u0026thinsp;\u0026plusmn;\u0026thinsp;5.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e32.64\u0026thinsp;\u0026plusmn;\u0026thinsp;5.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.203\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.840\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e44.96\u0026thinsp;\u0026plusmn;\u0026thinsp;4.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e44.88\u0026thinsp;\u0026plusmn;\u0026thinsp;4.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.156\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.877\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e56.24\u0026thinsp;\u0026plusmn;\u0026thinsp;9.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e55.35\u0026thinsp;\u0026plusmn;\u0026thinsp;9.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.871\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.387\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison the various parameters of of L1 and L2\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eL1 (N\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eL2 (N\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e115.72\u0026thinsp;\u0026plusmn;\u0026thinsp;9.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e95.56\u0026thinsp;\u0026plusmn;\u0026thinsp;11.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e17.140\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLE(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e8.21\u0026thinsp;\u0026plusmn;\u0026thinsp;1.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e10.60\u0026thinsp;\u0026plusmn;\u0026thinsp;3.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-5.556\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLH(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e15.85\u0026thinsp;\u0026plusmn;\u0026thinsp;3.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e26.53\u0026thinsp;\u0026plusmn;\u0026thinsp;3.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e29.509\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLI(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e83.78\u0026thinsp;\u0026plusmn;\u0026thinsp;7.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e62.87\u0026thinsp;\u0026plusmn;\u0026thinsp;13.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e13.468\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLP(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e27.30\u0026thinsp;\u0026plusmn;\u0026thinsp;5.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e27.81\u0026thinsp;\u0026plusmn;\u0026thinsp;5.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-2.220\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.030*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLS(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e34.16\u0026thinsp;\u0026plusmn;\u0026thinsp;6.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e32.82\u0026thinsp;\u0026plusmn;\u0026thinsp;5.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.752\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.047*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e38.33\u0026thinsp;\u0026plusmn;\u0026thinsp;4.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e46.05\u0026thinsp;\u0026plusmn;\u0026thinsp;4.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-16.200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e56.26\u0026thinsp;\u0026plusmn;\u0026thinsp;7.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e57.24\u0026thinsp;\u0026plusmn;\u0026thinsp;9.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-2.074\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.042*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab9\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 9\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison the various parameters of of R1 and R2\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR1 (N\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR2 (N\u0026thinsp;=\u0026thinsp;60)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e117.81\u0026thinsp;\u0026plusmn;\u0026thinsp;10.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e104.98\u0026thinsp;\u0026plusmn;\u0026thinsp;11.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e13.614\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLE(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e7.85\u0026thinsp;\u0026plusmn;\u0026thinsp;2.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-3.042\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.004*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLH(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e15.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e25.74\u0026thinsp;\u0026plusmn;\u0026thinsp;3.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-24.396\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLI(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e85.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e72.78\u0026thinsp;\u0026plusmn;\u0026thinsp;11.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e9.541\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLP(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e27.29\u0026thinsp;\u0026plusmn;\u0026thinsp;3.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e30.48\u0026thinsp;\u0026plusmn;\u0026thinsp;11.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-2.209\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.031*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLS(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e34.06\u0026thinsp;\u0026plusmn;\u0026thinsp;5.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e32.64\u0026thinsp;\u0026plusmn;\u0026thinsp;5.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.394\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.020*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eα(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e38.09\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e44.88\u0026thinsp;\u0026plusmn;\u0026thinsp;4.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-15.447\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eβ(\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e55.14\u0026thinsp;\u0026plusmn;\u0026thinsp;8.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e55.35\u0026thinsp;\u0026plusmn;\u0026thinsp;9.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.348\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.729\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eRegarding the measurement of the radius of the simulated screw trajectory, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, the radius of all simulated screw trajectories were greater than 4 mm, and the mean values were greater than 4.5 mm. No significant differences in the radius of any of the simulated screw trajectories were found between sexes or between entry point positions (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab10\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 10\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison the various parameters of screw trajectory radius\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMen\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWomen\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL1(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.78\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.72\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.734\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.466\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eL2(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.329\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.743\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eR1(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.176\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eR2(mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e-0.515\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.609\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eNote: * P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates statistically significant difference\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eR: Screw trajectory radius\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eTo our knowledge the free-hand dual S2AI technique for spinopelvic fixation in patients with deformity and undergoing scoliosis correction required revision has not been previously described in the literature[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Robotic-assisted nail placement can be safely and effectively performed in dual sacral-2 alar-iliac screw fixation, but this technology have yet to become common[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Relevant studies had shown that the rate of S2AI screw-related complications after ASD surgery were 10.8%[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] and 35%[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Tang et al indicate that dual S2AI screw fixation is a feasible technique in patients with severe kyphoscoliosis, providing satisfactory correction of coronal balance and sagittal alignment with few postoperative complications[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn corrective operation of deformities of the spine, especially in cases of severe deformity requiring complex revision require long-segment posterior fixation, the stability of the lumbosacral junction is crucial. It is largely dependent on the strength of pelvic fixation[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Instability of the lumbosacral junction may lead to pseudarthrosis and construct failure[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Although the instrumentation can be extended across to the lumbosacral, lumbosacral fixation still remains a difficult clinical challenge for spinal surgeons, especially in cases of complex revision and severe deformity[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In 2009, Sponsell et al.[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] reported the use of S2AI screws for pelvic fixation, which provides a distal fixation option for internal fixation in adults with degenerative scoliosis and kyphosis. It has achieved satisfactory clinical efficacies and has been widely used in recent years. However, in cases of complicated revision and severe deformity, a single S2AI as crew often cannot achieve ideal fixation. Paul J. Park[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] and Jamal N. Shillingford et al.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] reported the application of dual S2AI screws for the correction and revision of severe deformities and achieved clinical successes.\u003c/p\u003e \u003cp\u003eHowever, whether this technique is applicable in the Chinese adult population and whether it has general applicability have not yet been clearly stated. At present, no definitive study has explored three-dimensional measurement of the screw trajectory of dual S2AI screws on the same side in the Chinese adult population, and corresponding data guidance for the clinical application of this technique is lacking. In this study, we validated the use of ipsilateral dual S2AI screws in the Chinese adult population by collecting measurement data from three-dimensional models of patients, and measured relevant screw trajectory data, which had not been previously published. In patients with scoliosis, the normal relationships between parameters of sacropelvic and spinopelvic alignment are commonly altered. Therefore, it\u0026rsquo;s the bony landmarks of the pelvis not of the sacropelvic and spinopelvic that were chosen as references, which was not affected by the spinal deformity.\u003c/p\u003e \u003cp\u003eTo facilitate the installation of an internal fixation connecting rod, the entry point of the S2AI screw should be aligned with the starting points of S1 and L5 pedicle screws. The starting point of the S1 pedicle screw is the lower edge of the superior articular process of S1, which can be moved slightly outward without causing nerve injury[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Therefore, the lateral sacral crest of the S1 and S2 foramina was chosen as the reference for screw entry points[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The distance between the starting points was greater than 10 mm in all patients (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Therefore, we demonstrate that the outer edges of the sacral foramina at S1 and S2 of all patients could accommodate the end caps of two S2AI screws without causing screw placement failure due to interference of the end caps of the screws. Oue research, provide a basis for successful placement of two S2AI screws on the same side.\u003c/p\u003e \u003cp\u003eThe optimal screw trajectory for SAI screws is located in the iliac cancellous bone directly above the ischial notch. When the screw passes through the sacroiliac joint, both the iliac cancellous bone directly above the ischial notch and the cortical bone of the sacroiliac joint result in greater pullout strength[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] .The cortical bone during clinical application are rare, the cortical bone outside the screw trajectory of S2AI screws is surrounded by important neurovascular structures, in spite of few literature about S2AI screws significantly perforating the cortical bone during clinical application was reported [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In previous clinical applications of S2AI screws, clinicians were most concerned about the damage to the cortical bone of the greater sciatic notch, which could damage the sciatic nerve below the greater sciatic notch, the internal iliac artery and vein, and the posterior and posterosuperior supragluteal neurovascular bundles, injuries that often lead to more serious clinical consequences[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Compared with cranial L2 and R2 screws, L1 and R1 screws are closer to the greater sciatic notch and are thus more likely to cause damage to important tissues. Therefore, when simulating screw placement, we placed L1 or R1 first and then measured the distance from the top of the greater sciatic notch to the cross-section of the screw trajectory. Because the L2 and R2 screws are close to the upper end of the ilium, the important neurovascular injuries are less likely to occur. However, there is a thin area at the upper end of the ilium with a thickness less than 5 mm[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], therefore, screws should be placed as low as possible at this location, and thinner screws should be selected. The results showed that for the patients in this study, the simulated screw trajectories of all four screws did not interfere with or cross each other. Table\u0026nbsp;11 shows that the radii of the simulated L2 and R2 screw trajectories were smaller than those of the simulated L1 and R1 screw trajectories, which is consistent with the anatomical characteristics of ilium. Biomechanical and clinical results show that S2AI screws with a diameter less than 8 mm can break easily[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. In the patients in the present study, the diameters of all simulated screw trajectories were greater than 8 mm, which meet clinical requirements and provide better biomechanical stability.\u003c/p\u003e \u003cp\u003eCompared with conventional iliac screws, S2AI screws can reduce complications such as infection that caused by muscle stripping[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. In this study, the measured distances from the entry points of the L1, L2, R1 and R2 screws to the median sagittal plane were 27.30\u0026thinsp;\u0026plusmn;\u0026thinsp;5.34 mm, 27.81\u0026thinsp;\u0026plusmn;\u0026thinsp;5.16 mm, 27.29\u0026thinsp;\u0026plusmn;\u0026thinsp;3.63 mm and 30.48\u0026thinsp;\u0026plusmn;\u0026thinsp;11.08 mm, respectively, and there was no statistically significant difference among the four simulated screw entry points, indicating that the entry points of the two screws on the same side can be located on the same axis to facilitate the installation of the connecting rod. Moreover, statistical analysis showed that the screw entry points were closer to the middle of sacrum than the screw entry points of the Galveston rod fixation and iliac screw techniques, thereby reducing soft tissue dissection and the incidence of deep infection.\u003c/p\u003e \u003cp\u003eThe use of traditional screws for sacroiliac joint fixation often leads to postoperative discomfort at the sacroiliac joint due to the stimulation of the sacroiliac joint by the threads, among other causes[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The S2AI screw shank is designed as a smooth rod to reduce stimulation of the sacroiliac joint by the threads. The results of the optimal screw trajectory measurement in the patients in this study showed that the average length L of the L1 screw trajectory was 115.72\u0026thinsp;\u0026plusmn;\u0026thinsp;9.00 mm, and LS was 34.16\u0026thinsp;\u0026plusmn;\u0026thinsp;6.14 mm; the average length L of the L2 screw trajectory was 102.03\u0026thinsp;\u0026plusmn;\u0026thinsp;9.87 mm, and LS was 32.82\u0026thinsp;\u0026plusmn;\u0026thinsp;5.59 mm; the average length L of the R1 screw trajectory was117.81\u0026thinsp;\u0026plusmn;\u0026thinsp;10.59 mm, and LS was 34.06\u0026thinsp;\u0026plusmn;\u0026thinsp;5.71 mm; and the average length L of the R2 screw trajectory 104.98\u0026thinsp;\u0026plusmn;\u0026thinsp;11.33 mm, and LS was 32.64\u0026thinsp;\u0026plusmn;\u0026thinsp;5.54 mm. For S2AI screws with a length greater than 80 mm, the length of the smooth rod was 43 mm. The LS length in the simulated screw trajectory of the four screws was much less than 43 mm. As the total length of the screw increases, the length of the smooth rod also increases, which can effectively avoid discomfort at the sacroiliac joint caused by the stimulation from the screw thread after internal fixation.\u003c/p\u003e \u003cp\u003eThis study has several limitations. Firstly, the study used the anatomical data of outpatients or emergency patients, some of whom suffered from hip degeneration, lumbar degeneration, and even hip fracture. Therefore, the data obtained in this study should not be considered as a representative of the healthy population. Nonetheless, this study provides some basic information about the use of dual S2AI screws. The second limitation of this study is that it was based on the ideal trajectory of ipsilateral dual S2AI screws in geometric space without considering about the factors such as biomechanics. In clinical applications, the fixation effect of the screws must be evaluated, followed by a corresponding biomechanical analysis. Thirdly, the study contained a relatively small number of patients with a large age range, and further studies with a larger sample may be necessary.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn this study, we show that placing two S2AI screws with a radius\u0026thinsp;\u0026gt;\u0026thinsp;4 mm on the same side is feasible in the Chinese adult population, furthermore, in some patients, placing two S2AI screws with a radius\u0026thinsp;\u0026gt;\u0026thinsp;5 mm on the same side is also feasible. In addition, preoperative three-dimensional reconstruction and screw placement simulation using Mimics can effectively simulate ipsilateral dual S2AI screw placement, assist preoperative planning, and guide precise placement of the screws during the operation. Ipsilateral dual S2AI screws can avoid the insufficient biomechanical stability caused by single screw and the internal fixation failure.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor\u0026rsquo;s contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStudy conception and design were performed by Mengqi Xie, Chao Chen,\u0026nbsp;Baoshan Xu, and Yu Zhao. Acquisition of data was conducted by Mengqi Xie,\u0026nbsp;Zhi Wang, Dong Zhao, and Gang Liu. Analysis and interpretation of data were done by\u0026nbsp;Xun Sun, Xiaoman Dong, and\u0026nbsp;Shan Zhu. Drafting the manuscript was performed by\u0026nbsp;Mengqi Xie and Chao Chen. Critical revision of manuscript was conducted by\u0026nbsp;Xinlong Ma and\u0026nbsp;Qiang Yang. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by\u003cstrong\u003e\u0026nbsp;National Key R\u0026amp;D Program of China (2023YFC2416900). National Natural Science Foundation of China (82372419). Tianjin Science and Technology Plan Project \u0026ldquo;Unveiling and Directing\u0026rdquo; Major Project (21ZXJBSY00130).\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the\u0026nbsp;Ethics Committee of Tianjin Hospital（2020136）\u0026nbsp;and complied with the approved guidelines. The need for informed consent requirement was waived owing to the retrospective nature of the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll the authors declare that they have no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eMoshirfar A, Rand FF, Sponseller PD, Parazin SJ, Khanna AJ, Kebaish KM, et al. Pelvic fixation in spine surgery. Historical overview, indications, biomechanical relevance, and current techniques. J Bone Joint Surg Am. 2005;87 Suppl 2:89-106.\u003c/li\u003e\n\u003cli\u003eAllen BL, Jr., Ferguson RL. The Galveston technique of pelvic fixation with L-rod instrumentation of the spine. Spine (Phila Pa 1976). 1984;9(4):388-94.\u003c/li\u003e\n\u003cli\u003eTumialan LM, Mummaneni PV. Long-segment spinal fixation using pelvic screws. Neurosurgery. 2008;63(3 Suppl):183-90.\u003c/li\u003e\n\u003cli\u003eAgulnick M, Cohen BR, Epstein NE. Reconstruction of Shattered Lumbo-Sacral Junction/Pelvis Utilizing Bilateral L4-Sacrum Fibula Strut Allograft And Double Iliac Screws Plus Routine Lumbar Pedicle Screw Fixation. Surg Neurol Int. 2020;11:335.\u003c/li\u003e\n\u003cli\u003ePeelle MW, Lenke LG, Bridwell KH, Sides B. Comparison of pelvic fixation techniques in neuromuscular spinal deformity correction: Galveston rod versus iliac and lumbosacral screws. Spine (Phila Pa 1976). 2006;31(20):2392-8; discussion 9.\u003c/li\u003e\n\u003cli\u003eO\u0026apos;Brien JR, Matteini L, Yu WD, Kebaish KM. Feasibility of minimally invasive sacropelvic fixation: percutaneous S2 alar iliac fixation. Spine (Phila Pa 1976). 2010;35(4):460-4.\u003c/li\u003e\n\u003cli\u003eO\u0026apos;Brien JR, Yu WD, Bhatnagar R, Sponseller P, Kebaish KM. An anatomic study of the S2 iliac technique for lumbopelvic screw placement. Spine (Phila Pa 1976). 2009;34(12):E439-42.\u003c/li\u003e\n\u003cli\u003eRay WZ, Ravindra VM, Schmidt MH, Dailey AT. Stereotactic navigation with the O-arm for placement of S-2 alar iliac screws in pelvic lumbar fixation. J Neurosurg Spine. 2013;18(5):490-5.\u003c/li\u003e\n\u003cli\u003eWu AM, Chi YL, Ni WF, Huang YX. The feasibility and radiological features of sacral alar iliac fixation in an adult population: a 3D imaging study. PeerJ. 2016;4:e1587.\u003c/li\u003e\n\u003cli\u003eIlyas H, Place H, Puryear A. A Comparison of Early Clinical and Radiographic Complications of Iliac Screw Fixation Versus S2 Alar Iliac (S2AI) Fixation in the Adult and Pediatric Populations. J Spinal Disord Tech. 2015;28(4):E199-205.\u003c/li\u003e\n\u003cli\u003eFang T, Russo GS, Schroeder GD, Kepler CK. The Accurate Free-hand Placement of S2 Alar Iliac (S2AI) Screw. Clin Spine Surg. 2020;33(3):102-3.\u003c/li\u003e\n\u003cli\u003ePark PJ, Lin JD, Makhni MC, Cerpa M, Lehman RA, Lenke LG. Dual S2 Alar-Iliac Screw Technique With a Multirod Construct Across the Lumbosacral Junction: Obtaining Adequate Stability at the Lumbosacral Junction in Spinal Deformity Surgery. Neurospine. 2020;17(2):466-70.\u003c/li\u003e\n\u003cli\u003eAbdul-Jabbar A, Yilmaz E, Iwanaga J, Tawfik T, O\u0026apos;Lynnger TM, Schildhauer TA, et al. Neurovascular Relationships of S2AI Screw Placement: Anatomic Study. World Neurosurg. 2018;116:e108-e12.\u003c/li\u003e\n\u003cli\u003eHuang W, Xu L, Cai W, Cheng M, Sun Z, Wang S, et al. Freehand S2‐Alar‐Iliac Screw Placement Technique in Lumbosacral Spinal Tumors: A Preliminary Study. Orthopaedic Surgery. 2022;14(9):2195-202.\u003c/li\u003e\n\u003cli\u003eHiyama A, Ukai T, Ogasawara S, Tanaka T, Watanabe M. Minimally Invasive 360\u0026deg; Fusion Using a Combination of INFIX and Minimally Invasive Spinopelvic Fixation by Intraoperative Computed Tomography Navigation for Unstable Pelvic Ring Fracture: A Technical Note. Orthopaedic Surgery. 2023;15(5):1405-13.\u003c/li\u003e\n\u003cli\u003eHa AS, Hong DY, Luzzi AJ, Coury JR, Cerpa M, Sardar Z, et al. Minimum 2-Year Analysis of S2-Alar-Iliac Screw Fixation for Adult Spinal Deformity. Global Spine J. 2022;12(8):1640-6.\u003c/li\u003e\n\u003cli\u003eGuler UO, Cetin E, Yaman O, Pellise F, Casademut AV, Sabat MD, et al. Sacropelvic fixation in adult spinal deformity (ASD); a very high rate of mechanical failure. Eur Spine J. 2015;24(5):1085-91.\u003c/li\u003e\n\u003cli\u003eTang Z, Hu Z, Zhu Z, Qiao J, Mao S, Ling C, et al. The Utilization of Dual Second Sacral Alar‐Iliac Screws for Spinopelvic Fixation in Patients with Severe Kyphoscoliosis. Orthopaedic Surgery. 2022;14(7):1457-68.\u003c/li\u003e\n\u003cli\u003eLiu Zj, Hu Yc, Tian W, Jin X, Qi Ht, Sun Yx, et al. Robot‐Aided Minimally Invasive Lumbopelvic Fixation in Treatment of Traumatic Spinopelvic Dissociation. Orthopaedic Surgery. 2021;13(2):563-72.\u003c/li\u003e\n\u003cli\u003eWeistroffer JK, Perra JH, Lonstein JE, Schwender JD, Garvey TA, Transfeldt EE, et al. Complications in long fusions to the sacrum for adult scoliosis: minimum five-year analysis of fifty patients. Spine (Phila Pa 1976). 2008;33(13):1478-83.\u003c/li\u003e\n\u003cli\u003eCunningham BW, Sefter JC, Hu N, Kim SW, Bridwell KH, McAfee PC. Biomechanical comparison of iliac screws versus interbody femoral ring allograft on lumbosacral kinematics and sacral screw strain. Spine (Phila Pa 1976). 2010;35(6):E198-205.\u003c/li\u003e\n\u003cli\u003eKubaszewski L, Nowakowski A, Kaczmarczyk J. Evidence-based support for S1 transpedicular screw entry point modification. J Orthop Surg Res. 2014;9:22.\u003c/li\u003e\n\u003cli\u003eMattei TA, Fassett DR. Combined S-1 and S-2 sacral alar-iliac screws as a salvage technique for pelvic fixation after pseudarthrosis and lumbosacropelvic instability: technical note. J Neurosurg Spine. 2013;19(3):321-30.\u003c/li\u003e\n\u003cli\u003eGarin A, Abara S, Herrera C, Acuna I, Cancino J, Bettancourt S, et al. Delayed lower extremity paresis following iliosacral screws: Atypical complication and treatment. Trauma Case Rep. 2021;31:100380.\u003c/li\u003e\n\u003cli\u003eHasan MY, Liu G, Wong HK, Tan JH. Postoperative complications of S2AI versus iliac screw in spinopelvic fixation: a meta-analysis and recent trends review. Spine J. 2020;20(6):964-72.\u003c/li\u003e\n\u003cli\u003eMarmor M, Lynch T, Matityahu A. Superior gluteal artery injury during iliosacral screw placement due to aberrant anatomy. Orthopedics. 2010;33(2):117-20.\u003c/li\u003e\n\u003cli\u003eLiu F, Yang Y, Wen C, Guo L, Wang A, Huang W, et al. Morphometric measurement and applicable feature analysis of sacral alar-iliac screw fixation using forward engineering. Arch Orthop Trauma Surg. 2020;140(2):177-86.\u003c/li\u003e\n\u003cli\u003eJain A, Kebaish KM, Sponseller PD. Sacral-Alar-Iliac Fixation in Pediatric Deformity: Radiographic Outcomes and Complications. Spine Deform. 2016;4(3):225-9.\u003c/li\u003e\n\u003cli\u003ePhillips JH, Gutheil JP, Knapp DR, Jr. Iliac screw fixation in neuromuscular scoliosis. Spine (Phila Pa 1976). 2007;32(14):1566-70.\u003c/li\u003e\n\u003cli\u003eYoshihara H. Sacroiliac joint pain after lumbar/lumbosacral fusion: current knowledge. Eur Spine J. 2012;21(9):1788-96.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Spine surgery, Spinopelvic fixation, Dual sacral-2 alar-iliac screw, Screw trajectory, Three-dimensional, Mimics","lastPublishedDoi":"10.21203/rs.3.rs-3927343/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3927343/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eThe purpose of this study was to evaluate the feasibility and the trajectories of dual sacral-2 alar-iliac (S2AI) screw fixation with three-dimensional digital technology simulation analysis.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThe pelvic computed tomography scan data of 60 (30 men and 30 women, age: 25\u0026ndash;86 years) individuals were selected and reconstructed. The trajectories of dual S2AI screws were plotted using three-dimensional reconstruction software. A cylinder with a radius of 5 mm was selected to simulate screw placement. If screw placement based on the cylinder with 5 mm radius failed, selected a cylinder with a radius of 4.5 mm or 4 mm. Dual S2AI trajectories were simulated, the maximum length and width of the trajectories were ensured, and their parameters were precisely measured. All parameters were measured in the three-dimensional image, including distance parameters, radius and angles.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe placement of dual S2AI screws on the same side could be achieved in all individuals. No significant differences were found between the male and female regarding the head inclination angle, abduction angle, and total length or thread length of screws in the same position (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). LH(the shortest distance from the greater sciatic notch to the cross-section of the screw trajectory)were17.52\u0026thinsp;\u0026plusmn;\u0026thinsp;3.96 mm and 14.18\u0026thinsp;\u0026plusmn;\u0026thinsp;2.92 mm in L1,28.19\u0026thinsp;\u0026plusmn;\u0026thinsp;2.58 mm and 25.54\u0026thinsp;\u0026plusmn;\u0026thinsp;4.15 mm in L2, 16.09\u0026thinsp;\u0026plusmn;\u0026thinsp;4.08 mm and 14.71\u0026thinsp;\u0026plusmn;\u0026thinsp;3.94 mm in R1, 26.90\u0026thinsp;\u0026plusmn;\u0026thinsp;3.76 mm and 24.59\u0026thinsp;\u0026plusmn;\u0026thinsp;2.85 mm in R2 in male and female models, respectively. The shortest distance from the greater sciatic notch to the cross-section of the screw trajectory differed significantly between the sexes (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eUsing a radius of 4 mm (minimum diameter of S2AI screw) as a standard, it is feasible to place two S2AI screws on the same side for the Chinese adult. Screw placement can be achieved by trisecting the lateral process of S1-S2, with one screw inserted in the bottom third and the other in the upper third. Furthermore, preoperative three-dimensional digital technology simulation analysis can effectively simulate the dual S2AI screws trajectories on the same side, and they can provide accurate data for clinical applications.\u003c/p\u003e","manuscriptTitle":"Radiographic Parameters and feasibility analysis of dual sacral-2 alar-iliac screw fixation using three-dimensional digital technology","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-09 17:12:54","doi":"10.21203/rs.3.rs-3927343/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"44e28c45-5a39-4952-9c46-bec9299a53dd","owner":[],"postedDate":"February 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-02-22T15:52:24+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-09 17:12:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3927343","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3927343","identity":"rs-3927343","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}