Objective:To establish a digital anatomical model of the pelvic and compare the differences in morphological parameters of the infra-acetabular screw safety channel between men and women.Methods:A retrospective analysis was performed on the pelvic data of 106 normal adults who underwent plain pelvic CT scan for non-pelvic disorders diseases in the Affiliated Hospital of Traditional Chinese Medicine of Xinjiang Medical University from January 2022 to December 2022, including 56 males and 50 females, aged 50.58±11.22 years (range, 21-68 years). Use reverse reconstruction software to reconstruct the pelvis and import it into Autodesk maya 2022 software to level the model. Use polygonal modeling tools to simulate the insertion of infra-acetabular screws and measure the length of the screw, the screw insertion angle, and the distance between the needle entry point and the apex of the iliopubic eminence. Measure the diameter of the infra-acetabular screw through axial fluoroscopy; measure the needle entry area, narrow area and needle exit area in Mimics 21.0 software; compare the differences in the above indicators between men and women.Results:The maximum diameters of male and female infra-acetabular screws were 4.82±1.07 mm and 3.93±0.65 mm respectively; the maximum lengths were 97.74±93.8 mm and 88.23±4.55 mm respectively; the angles with the sagittal plane were -1.33°±4.96°and 7.29°±6.20° respectively; the needle insertion areas were 314.83±4.79 mm 2 and 198.29±78.70 mm 2 respectively, the narrow areas were 75.61±19.00 mm 2 and 47.33±13.34 mm 2 respectively, and the needle exit areas were 400.52±88.86 mm 2 and 268.27±120.71 mm 2 respectively; the differences between male and female were statistically significant ( P<0.05). The infra-acetabular screw insertion points for men and women are respectively 9.39±1.44 mm and 9.68±1.41 mm inside the iliopubic eminence apex, and 8.87±1.22 mm and 9.28±1.56 anterior to the iliopubic eminence apex; the angles between the infra-acetabular screw and the anterior pelvic plane were 52.69°±7.38°and 52.32°±1.24°respectively; the differences were not statistically significant ( P>0.05). When the screw diameter was 3.5 mm, 88% (49/56) of men and 76% (38/50) of women have corridor in the pelvis for screws to pass through, and the difference was not statistically significant (χ 2=2.375, P=0.123). But when the screw diameter was 4.5 mm, 59% (33/56) of men and 20% (10/50) of women have corridor in the pelvis for screws to pass through, and the difference was statistically significant (χ 2=16.603, P<0.001). Conclusion:There are large individual differences in infra-acetabular corridor parameters. The length, diameter, needle entry area, narrow area and needle exit area of the infra-acetabular screw in men are larger than those in women, while the angle with the sagittal plane in men is smaller than that in women. There is no significant difference between men and women in the distance between the insertion point of the infra-acetabular screw and the iliopubic eminence and the angle between the screw and the anterior pelvic plane. There was no significant difference in the pass rate of screws with a diameter of 3.5 mm between males and females in the acetabular canal, while the pass rate of screws with a diameter of 4.5 mm was higher than that of females.

Objective:To investigate the clinical efficacy of over-the-top reconstruction combined with the modified Lemaire technique in the treatment of anterior cruciate ligament (ACL) injuries with pivot-shift positive.Methods:From March 2020 to October 2021, a total of 46 patients with ACL injury and pivot-shift test grade II or above were admitted to Xinhua Hospital Affiliated to Dalian University. There were 28 males and 18 females, aged 28.0±10.5 years (range, 15-45 years). All cases were unilateral, including 17 cases of left knee and 29 cases of right knee. The pivot-shift test showed that 30 cases were grade II and 16 cases were grade III, and the cause of injury was sports injury. The semitendinosus muscle and gracilis muscle were harvested, and the ACL was reconstructed with the over-the-top combined modified Lemaire technique. The International Knee Documentation Committee (IKDC) score, Lysholm score and KT-2000 side-to-side difference before and after operation were compared.Results:All patients successfully completed the operation and were followed up for 26.6±2.3 months (range, 24-28 months). The Lysholm scores of the patients at 3 months and 24 months after operation were 73.6±4.3 and 91.6±2.8, which were higher than those before operation (58.5±4.6), and the difference was statistically significant ( F=18.351, P<0.001). The IKDC scores of patients at 3 months and 24 months after operation were 59.0±2.0 and 91.8±3.2, respectively, which were higher than those before operation 50.3±2.8, and the difference was statistically significant ( F=17.290, P<0.001). The side-to-side difference of KT-2000 was 1.7±0.8 mm and 1.5±0.4 mm at 3 and 24 months after operation, respectively, which was lower than that before operation (5.9±1.1 mm), and the difference was statistically significant ( F=14.192, P<0.001). At 24 months after operation, 3 patients had pivot shift test grade I and 4 patients had Lachman test grade I, but they complained of good knee stability and did not receive further treatment. At the last follow-up, there were no complications such as incision and intra-articular infection, deep vein thrombosis, knee stiffness, quadriceps musculus ossificans myositis, and reconstruction ligament rupture. All patients returned to sports with an average time of 15.7±2.6 months (range, 12-24 months). Conclusion:Over-the-top reconstruction combined with the modified Lemaire technique for the treatment of ACL injury with positive pivot shift test effectively improves knee function and promotes the patient's return to sports, with a low incidence of surgical complications.

Objective:To compare the postoperative tunnel enlargement and clinical outcomes of anterior cruciate ligament (ACL) reconstruction using the all-inside technique with the traditional outside-in graft introduction technique.Methods:A retrospective analysis was conducted on 47 patients with ACL injuries who were admitted to the First Hospital of the University of Science and Technology of China between December 2021 and July 2022. The patients were categorized into two groups based on the surgical approach used for ACL reconstruction. There were 25 cases in the all-inside group, 18 males and 7 females, aged 27.72±7.33 years, 17 cases on the left side and 8 cases on the right side; 22 cases in the traditional group, 11 males and 11 females, aged 27.82±7.12 years, 11 cases on the left side and 11 cases on the right side. Clinical parameters including the length of hospital stay, surgical duration, pain levels assessed via the visual analogue scale (VAS), Lysholm score, International Knee Documentation Committee (IKDC) score, and Tegner score were recorded and compared between the two groups. Additionally, femoral and tibial tunnel enlargement was evaluated using postoperative CT scans conducted one year after surgery.Results:All patients were followed up for 15.64±2.04 months (range, 12-21 months). The mean operation time was 178.60±42.90 min in the all-inside group and 133.60±28.77 min in the traditional group, indicating a statistically significant longer operation time in the all-inside group ( P<0.05). On postoperative days 1 and 15, the VAS scores were lower in the all-inside group (7.08±1.29 and 5.56±1.33 points) compared to the conventional group (7.96±1.29 and 6.32±1.13 points), with a statistically significant difference ( P<0.05). However, the differences in VAS scores between the two groups at postoperative months 1, 6, and 12 were not statistically significant ( P>0.05). The preoperative Lysholm, IKDC, and Tegner scores in the all-inside group and the conventional group were 34.00±18.63, 36.24±15.01, 1.20±1.12 points and 36.18±13.64, 38.23±14.94, 1.55±1.14 points, respectively, and at 6 months after surgery, respectively were 72.60±13.95, 74.12±12.03, 3.56±1.05 points, and 68.41±10.80, 66.59±17.93, 3.23±1.15 points, and at 12 months postoperatively were 92.32±5.23, 81.40±7.24, 5.28±1.62 points and 91.27±6.32, 82.18±7.26, 4.96±1.25 points. Both groups improved at 6 months postoperatively compared with preoperatively ( P<0.05), and further improved at 12 months postoperatively compared with 6 months postoperatively ( P<0.05), but the differences in each functional score between the two groups were not statistically significant at all time points ( P>0.05). At 1 year postoperatively, the values of femoral and tibial tunnel enlargement in the all-inside group (1.78±1.03 mm, 1.18±0.97 mm) were smaller than those in the conventional group (2.30±1.33 mm, 1.83±1.00 mm), and the differences were statistically significant ( P<0.05). The difference between the femoral side tunnel enlargement and tibial side enlargement in the traditional group was not statistically significant ( P>0.05), while the femoral side enlargement in the all-inside group was significantly larger than the tibial side ( P<0.05). The difference in Lysholm, IKDC and Tegner scores between grade 0 and grade 1 tunnel enlargement on the femoral side and tibial side was not statistically significant ( P>0.05). Conclusion:The short-term clinical outcomes following ACL reconstruction using the all-inside technique versus the traditional tunnel technique were comparable. However, early postoperative pain was less severe with the all-inside technique, and tunnel enlargement was smaller. The degree of bone tunnel enlargement did not significantly impact early clinical outcomes.

Objective:To investigate the application value of computer-assisted preoperative planning (CAPP) in the treatment of AO/OTA type-C distal femoral fractures.Methods:A retrospective analysis was conducted on 150 patients with AO/OTA type-C distal femur fractures from January 2010 to December 2021 using the less invasive stabilization system-distal femur (LISS-DF). Patients were divided into a non-CAPP group and a CAPP group based on whether computer-assisted preoperative planning was utilized. The non-CAPP group included 81 patients (56 males, 25 females) with an age range of 39 to 67 years (mean 54.9±5.8 years), consisting of 22 type-C1 fractures, 35 type-C2 fractures, and 24 type-C3 fractures. The CAPP group comprised 69 patients (50 males, 19 females) with an age range of 45 to 63 years (mean 53.9±4.6 years), including 18 type-C1 fractures, 28 type-C2 fractures, and 23 type-C3 fractures. The study recorded the time of preoperative planning and compared the surgical duration, intraoperative blood loss, times of fluoroscopy intraoperatively, and hospital stay length between the two groups. At the last follow-up, knee function was evaluated using the Hospital for Special Surgery (HSS) knee score and pain was assessed using the visual analogue scale (VAS).Results:The preoperative planning time of CAPP was 22.5±3.4 min (range, 17-31 min). There were statistically significant differences between non-CAPP group and CAPP group in terms of surgical duration (non-CAPP, 110.9±7.7 min; CAPP, 94.4±6.3 min), intraoperative blood loss (non-CAPP, 299.3±34.2 ml; CAPP, 224.1±22.0 ml), times of fluoroscopy intraoperatively (non-CAPP, 11.3±3.1; CAPP, 6.7±2.2), and hospital stay length (non-CAPP, 12.8±3.2 d; CAPP, 6.4±1.9 d) ( P<0.001). All patients were followed up, with the CAPP group having a follow-up duration of 17.7±3.3 months and the non-CAPP group having 18.1±3.7 months. Both groups of patients achieved clinical healing of fractures. The healing time for fractures in the CAPP group and the non-CAPP group were 13.9±1.1 weeks and 14.0±1.3 weeks, respectively, with no statistically significant difference ( t=0.699, P=0.490). At the last follow-up, the average HSS score and VAS score of the patients in the CAPP group were 86.6±3.4 points and 0.9±0.4 points, which were both better than those of the non-CAPP group 79.2±5.1 points and 1.3±0.5 points ( P<0.001). No patients in either group experienced complications related to delayed fracture healing, nonunion, or internal fixation failure. Conclusion:When using LISS -DF steel plate to treat complex distal femoral fractures, CAPP can assist the operator in efficiently and accurately completing preoperative design. Compared with traditional preoperative planning, it can reduce surgical time, surgical trauma, and achieve more satisfactory postoperative outcomes.

Objective:To investigate the clinical efficacy of total laparoscopic technique in the treatment of pelvic and acetabular fractures.Methods:A total of 7 patients with pelvic and acetabular fractures admitted to the First Affiliated Hospital of Nanjing Medical University from April 2017 to August 2023 were retrospectively analyzed. There were 5 males and 2 females, aged 43.9±9.9 years (range, 27-56 years). There was 1 pelvic fracture (Tile B3) and 6 acetabular fractures, Letournel typing transverse in 2 cases, double column in 1 case, transverse combined anterior column in 1 case, anterior column in 1 case, and "T" shape in 1 case. The causes of injury included traffic accident in 4 cases, falling from height in 1 case, falling in 1 case, and heavy object injury in 1 case. The operation time, intraoperative blood loss, iatrogenic injuries of blood vessels, nerves, bladder and rectum, and incidence of postoperative complications were recorded. Matta imaging criteria was used to evaluate the quality of fracture reduction, and the hip function was evaluated by modified Merle d'Aubigné-Postel score.Results:All 7 patients were successfully operated and followed up for 12.0 (7.0, 72.0) months (range, 7-77 months). The operation time was 251.1±80.2 min (range, 150.0-370.0 min), and the intraoperative blood loss was 100.0 (50.0, 300.0) ml (range, 50-350 ml). There was no nerve, blood vessel, bladder or rectum injury during operation. Postoperative pelvic X-ray and CT showed no internal fixation into the joint. Anatomic reduction was achieved in 5 cases and satisfactory reduction in 2 cases. One patient with a transverse acetabular fracture had a slight separation and displacement of the posterior column, but the acetabular articular surface was flat as a whole without obvious steps and was not fixed. One patient with pelvic fracture had a comminuted anterior pelvic ring with severe displacement and did not achieve anatomical repositioning intraoperatively, but the anterior pelvic ring was a non-intra-articular fracture, and the fracture ends were immobilized with bilateral plates, and the morphology and stability of the anterior pelvic ring recovered well after the operation. The Merle d'Aubigné - Postel score at the final follow-up was 18.0 (17.0, 18.0) points (range, 17.0-18.0 points), with 4 excellent and 3 good cases. All 7 patients achieved clinical healing with a healing time of 2.5 (2.5, 3.0) months (range, 1.0-3.0 months). No delayed union or nonunion occurred. At the last follow-up, there were no complications such as internal fixation fracture, incision and internal fixation infection, and deep vein thrombosis.Conclusion:Total laparoscopic technique for the treatment of pelvic and acetabular fractures has less intraoperative blood loss, less surgical trauma, and satisfactory clinical efficacy. It can be used as a new choice of minimally invasive treatment of pelvic and acetabular fractures.

Objective:To investigate the clinical efficacy of robot-assisted screw fixation for unstable pelvic ring multifocal fractures.Methods:A retrospective analysis was performed on 76 patients with unstable pelvic fractures treated with orthopaedic robot-assisted screw fixation in the Trauma Center of the Affiliated Central Hospital of Shandong First Medical University from January 2015 to June 2022, including 43 males and 33 females, aged 52.53±13.68 years (range, 16-87 years). There were 43 cases of falling injuries from high places, 22 cases of traffic accidents, 11 cases of crushing injuries and heavy objects. Fifty-five patients were employed before the injury, while 21 were not. Fractures were classified according to the Tile classification, with 72 cases classified as type B and 4 cases as type C. Robot-assisted fixation techniques included internal fixator (INFIX), anterior ring screws, sacroiliac screws, and LC-II screws. Intraoperative blood loss, fluoroscopy frequency, surgical time, and the success rate of initial guidewire placement were recorded. Fracture reduction quality was evaluated using the Matta criteria, and postoperative pelvic function recovery was assessed using the Majeed criteria.Results:A total of 150 surgical procedures were performed on 76 patients, including 34 cases of INFIX fixation, 48 cases of anterior ring screws, 61 cases of sacroiliac joint screws, and 7 cases of LC-II screws. The mean intraoperative fluoroscopy frequency was 46.63±17.50 times (range, 15-93 times). Intraoperative fluoroscopy frequency varied among different fixation techniques, with INFIX group at 16.44±4.32 times, LC-II group at 21.59±5.80 times, anterior ring screws group at 29.44±11.65 times, and sacroiliac screws group at 23.10±11.87 times. The intraoperative blood loss was 20 (10, 47.5) ml (range, 5-300 ml), and the surgical time was 105 (86, 150) min (range, 30-290 min). The mean surgical time varied among different fixation techniques. All patients were followed up for an average of 6.46±2.26 months (range, 3-16 months). Clinical healing was achieved in all patients within 6 months, with an average time of 3.14±0.50 months. At the last follow-up, fracture reduction quality assessed by the Matta score was excellent in 21 cases and good in 43 cases, with an excellent/good rate of 84% (64/76). The Majeed score was 81.82±9.14 points (range, 50-92 points). For patients who were employed before the injury, the Majeed score was 86.55±4.85 points (range, 60-92 points), with 49 cases rated as excellent, 5 cases as good, and 1 case as fair. For patients who were not employed before the injury, the Majeed score was 69.43±5.34 points (range, 50-73 points), with 18 cases rated as excellent, 2 cases as good, and 1 case as fair. The overall excellent and good rate was 97% (74/76). Among patients who underwent INFIX internal fixation, 8 cases experienced lateral femoral cutaneous nerve injury postoperatively, all of which recovered sensation after 3 months; 1 case using LC-II screws experienced screw loosening postoperatively and was advised to reduce activity, then the screw was removed after fracture healing at 6 months postoperatively; 1 case using anterior ring channel screws experienced surgical site infection postoperatively, which was controlled after debridement.Conclusion:In the treatment of unstable pelvic ring multiple fractures, robot-assisted screw fixation has less blood loss, less fluoroscopy times, high success rate of planning guide needle, satisfactory reduction quality and postoperative function.

Objective:To evaluate the clinical efficacy of modified anterior subacromial approach plate internal fixation for three- or four-part valgus impacted proximal humeral fractures.Methods:A retrospective analysis of 35 patients treated between November 2018 and November 2021 at Fuzhou Second General Hospital was performed, including 15 males and 20 females aged 61.7±7.8 years (range: 40 to 73 years). Patients were classified under the Neer system; 17 had 3-part fractures and 18 had 4-part fractures. The modified approach accessed the fracture site via the natural interval of the deltoid anterior bundle, facilitating fracture reduction and fixation using a plate. Operative time, incision length, intraoperative fluoroscopy time, follow-up duration, Constant-Murley score, fracture healing time, visual analogue scale (VAS) for pain, and humeral neck-shaft angle were assessed. Intraoperative and postoperative complications were also recorded.Results:All patients underwent successful surgery, with an average incision length of 8.1±0.3 cm (range, 7.6-9.0 cm) and intraoperative fluoroscopy time of 6.6±0.3 seconds (3-part fractures: 6.3±0.2 s, 4-part fractures: 6.8±0.2 s, t=6.350, P<0.001). Follow-up averaged 22.1±5.8 months (range, 14-31 months). Fracture healing occurred in 11.8±1.4 weeks (range, 10-15 weeks). At the final assessment, the VAS score was 1.6±0.7 (range, 1-3), the Constant-Murley score was 89.6±2.9 (range, 84-95), and the humeral neck-shaft angle was 133.4°±3.1° (range, 128°-138°; 3-part fractures: 133.6°±3.5°, 4-part fractures: 133.3°±2.8°, t=0.288, P=0.075). No complications such as avascular necrosis of the humeral head, varus collapse of the fracture site, or axillary nerve injury were recorded. Conclusion:The modified anterior subacromial approach plate internal fixation is a minimally invasive, safe, and effective treatment for valgus impacted three- and four-part proximal humeral fractures, demonstrated by excellent surgical outcomes and absence of major complications.

Objective:To investigate the initial effectiveness of manual techniques versus navigation positioning system-assisted reconstruction for anterior cruciate ligament (ACL) injuries in children and adolescent populations.Methods:A retrospective analysis was conducted on 28 patients with ACL rupture who underwent primary total epiphyseal ACL reconstruction in the Sports Medicine Treatment Center of Honghui Hospital Affiliated to Xi'an Jiaotong University from January 2019 to October 2022. Patients were categorized into two groups based on the method of guide needle insertion: the manual group (guide needle insertion relying on the operator's expertise) and the robot-assisted group (guide needle insertion assisted by the Tianji robot navigation and positioning system). The manual group comprised 14 cases (9 males, 5 females) with an average age of 13.59±1.59 years, while the robot-assisted group included 14 patients (10 males, 4 females) with an average age of 13.27±1.66 years. The operation time, intraoperative fluoroscopy times, guide needle placement times, the distance between the central point of the internal articular opening of the tibial and femoral bone tunnel and the ideal point, the rate of epiphyseal inflammation, and the International Knee Documentation Committee (IKDC) subjective score, Lysholm score, KT-2000 ligament relaxation, lower limb force line were compared between the two groups.Results:The follow-up duration was 19.9±6.3 months for the manual group and 18.8±4.9 months for the robot group ( t=0.546, P=0.589). The manual group's operation duration was 123.0±12.6 min, significantly longer than the robot group's 96.4±12.9 min ( t=5.502, P<0.001). Intraoperative fluoroscopy was performed 11.8±3.1 times in the manual group, markedly more than the robot group's 3.7±0.8 times ( t=9.434, P<0.001). The robot group required only one guide needle placement for both femur and tibia, while the manual group had 5.7±1.2 placements on the femur side and 4.6±1.8 on the tibia side. The distance between the femoral joint's central point and the ideal point was 0.87±0.20 mm in the robot group, superior to the manual group's 1.92±0.64 mm ( t=5.816, P<0.001). Similarly, the distance between the central point and the ideal point was 1.15±0.34 mm for the robot group, better than the manual group's 1.94±0.55 mm ( t=4.582, P<0.001). No cases of epiphyseal irritation were observed in the robot group, while 21% (3/14) of the manual group experienced tibial or femoral epiphyseal plate involvement. At 3 months post-surgery, the robot group exhibited higher IKDC subjective scores (90.57±8.46) and Lysholm scores (86.29±5.09) compared to the manual group (83.50±6.19 and 80.93±5.93), respectively ( P<0.05). However, at the final follow-up, there were no significant differences in IKDC subjective scores, Lysholm scores, or KT-2000 ligament relaxation between the two groups ( P>0.05). Both groups showed normal lower limb force alignment and no abnormal growth or development. Conclusion:Tianji robot navigation and positioning system-assisted ACL reconstruction in children and adolescents offer advantages such as precise positioning, shorter operation times, reduced intraoperative fluoroscopy, faster recovery, and enhanced epiphyseal protection compared to manual methods.

Objective:To investigate the effect of internal fixation of medial support and lateral wall on initial weight-bearing stability of femoral intertrochanteric fracture after reconstruction of intertrochanteric fracture.Methods:Based on the digital model of Sawbones femur, intertrochanteric fracture models with different medial support and lateral wall states were constructed. Combined with various intramedullary and extramedullary fixation methods, the mechanical models after fixation were simplified, and seven mechanical simplified models were obtained. The individual body weight load (70 kg) was simulated by applying concentrated force (700 N) to the end nodes of the femoral head. Through the analysis and calculation of each model in StrucMaster software, the axial force, shear force, bending moment, displacement deformation, and support reaction force of each bar in each mechanical model were obtained, and the results were output through the supporting SMConsole.Results:The median bending moment of model 1 was 11.55(5.57, 18.00) N·m, and the median bending moment was 2.89(2.81, 2.94) rad. The median bending moment of model 2 was 13.72(9.30, 20.05) N·m, and the median bending moment was 2.93(2.77, 3.05) rad. The median bending moment of model 3 was 19.65(10.23, 26.11) N·m, and the median bending moment was 2.93 (2.77, 3.05) rad. The median bending moment of model 4 was 25.95(25.14, 36.70) N·m, and the median bending moment was 4.38(3.16, 5.15) rad. The median bending moment of model 5 was 13.66(7.99, 25.62) N·m, and the median bending moment was 3.50(3.32, 3.56) rad. The median bending moment of model 6 was 24.60(9.33, 29.37) N·m, and the median bending moment was 3.90(3.69, 4.10) rad. The median bending moment of model 7 was 41.14(0.16, 41.30) N·m, and the median bending moment was 5.50(5.50, 7.05) rad. The mechanical properties of model 1 were better than those of the other six models.Conclusion:The simplified mechanical model and its mechanical calculation analysis based on the lever reconstruction balance theory can be used to preliminarily reveal the mechanical characteristics of femoral intertrochanteric fractures after internal fixation. The internal fixation methods of the medial support and lateral wall of femoral intertrochanteric fracture reconstruction can improve the initial stability of the weight bearing after internal fixation of femoral intertrochanteric fractures and have guiding significance for the functional rehabilitation of early postoperative weight bearing.

Objective:To develop a set of lowest instrumented vertebra (LIV) selection criteria for adolescent idiopathic scoliosis (AIS) with Lenke 1A curves named as "Gulou Rule", and compared with the traditional "last substantially touching vertebra (LSTV) Rule".Methods:Based on our previous retrospective studies about LIV selection, as well as our clinical experience, the key parameters associated with LIV selection were found out and quantified to form the "Gulou Rule". A prospective consecutive collection of 189 Lenke 1A cases (male 29 cases, female 160 cases) who underwent posterior spinal fusion surgery in our clinic from January 2021 to January 2022 were recruited, with an average age of 14.9±2.8 (range 10-18) years old. They were divided into 2 groups according to the enrollment number (odd or even number). Patients with odd numbers were guided by the "LSTV Rule",while those with even numbers followed the "Gulou Rule" for the selection of LIV. The duration of follow-up was at least two years. Radiographical parameters were measured preoperatively, immediately postoperatively, and at the final follow-up, including numbers of fused segments, Cobb angle of proximal thoracic curve, main thoracic curve and lumbar curve, correction rate, coronal and sagittal balance parameters. The incidence of distal adding-on at the last follow-up was recorded.Results:The "Gulou Rule" was defined as follows: when Risser ≥3, main curve length ≤8 segments, one level proximal to LSTV (LSTV-1) rotation ≤ I degree, LSTV-1 deviation from the CSVL <20 mm, preoperative coronal balance <10 mm, and the intervertebral disc between LSTV-1 and LSTV opens bidirectionally on bending films, the LIV can be selected as LSTV-1; if these conditions are not met, LIV should be selected as LSTV. At last, 120 patients (male 21 cases, female 99 cases) were enrolled in the study with at least a 2-year follow-up, with an average age of 15.1±2.4 (range 10-18) years old. Each group had 60 patients, and the average duration of follow-up was 31.0±5.4 months for the "LSTV Rule" group and 30.8±5.1 months for the "Gulou Rule" group. The LIV in the "Gulou Rule" group was on average at the T 12 and L 1 level, where as in the "LSTV Rule" group, it was at the L 1 and L 2 level ( P=0.004). The "LSTV Rule" group had an average fused segments of 10.5±1.7, while the "Gulou Rule" group was significantly lower with 9.7±1.5 segments ( t=2.760, P=0.003). At the last follow-up, the main curve correction rates were 74.8%±10.5% and 73.2%±12.3%, respectively, with no significant difference ( t=0.779, P=0.219). The incidence of distal adding-on phenomenon was 15% in the "LSTV Rule" group and 17% in the "Gulou Rule" group, with no significant difference between the two groups (χ 2=0.063, P=0.803). Conclusion:For Lenke 1A AIS patients, both the "Gulou Rule" and the "LSTV Rule" for guiding LIV selection can achieve satisfactory correction outcomes. Choosing LIV based on the "Gulou Rule" allows for the preservation of distal fusion segments and demonstrates better clinical applicability.