Measurement and clinical validation of safe distance for LC-<b>Ⅱ</b> screw placement using iliac oblique view_Chinese Journal of Reparative and Reconstructive Surgery

Authors：

FU Hongwei , WANG Ansu ,  CHEN Lin

Department of Orthopedics, Affiliated Hospital of Zunyi Medical University, Zunyi Guizhou, 563000, P. R. China;

Corresponding author：

CHEN Lin, Email: chenlinwhy@163.com

Keywords：

Pelvic fracture; LC-Ⅱ screw; bony trajectory; obturator outlet view; screw placement accuracy

DOI：

10.7507/1002-1892.202505096

Video：

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Objective To define a safe distance range from the LC-II screw trajectory to the apex of the greater sciatic notch based on pelvic CT measurements, and to clinically assess the feasibility of using this range under obturator outlet view combined with iliac tangential view fluoroscopy to guide screw insertion. Methods CT scans of 104 normal pelvises collected between January 2022 and February 2025 were analyzed. There were 52 males and 52 females, with a median age of 45.8 years (range, 19-76 years). The RadiAnt DICOM Viewer software was used to reconstruct coronal, sagittal, and axial sections of the potential LC-II screw trajectory. The maximum safety distance (Dmax) and the optimal safety distance (Dopt) from this trajectory to the greater sciatic notch were measured on the coronal and sagittal views. A retrospective analysis was conducted on 21 patients with LC-Ⅱ type pelvic fractures treated with the LC-Ⅱ screws fixation. And the screws were placed within the pre-defined safe distance under guidance from the obturator outlet and iliac tangential views. Postoperative CT scans were obtained to evaluate the accuracy of screw placement. Results Radiographic measurements from the 104 subjects showed that Dmax ranged from 1.87 to 3.87 cm (mean, 2.79 cm), and Dopt ranged from 1.01 to 2.92 cm (mean, 1.84 cm). Both Dmax and Dopt were significantly greater in the males than in the females (P>0.05). No significant difference was found between the left and right sides within the same gender (P>0.05). All 21 patients successfully underwent fracture reduction and fixation, with a total of 23 LC-Ⅱscrews implanted. According to the Lonstein grading system, the screw placement accuracy was rated as excellent in 16 screws, good in 3, fair in 3, and poor in 1, with an excellent and good rate of 82.6%. Conclusion Utilizing a CT-defined safe distance range from the screw trajectory to the greater sciatic notch, and adhering to this range under obturator outlet view combined with iliac tangential view fluoroscopy, enables the accurate and precise placement of LC-Ⅱ screws.

1.	Hermans E, Edwards MJR, Goslings JC, et al. Open pelvic fracture: the killing fracture? J Orthop Surg Res, 2018, 13(1): 83. doi: 10.1186/s13018-018-0793-2.
2.	Zhang BF, Shang K, Wang PF, et al. Comparison of posterior ring fixation with combined anterior and posterior ring fixation for the treatment of lateral compression type 2 pelvic fractures. Int Orthop, 2020, 44(6): 1187-1193.
3.	Wu Y, Chen H, Zhou X, et al. Lateral compression type 2 pelvic fractures-a clinical study of fracture displacement measurement and closed reduction. Orthop Surg, 2022, 14(10): 2545-2552.
4.	Simonian PT, Routt ML. Biomechanics of pelvic fixation. Orthop Clin North (Am), 1997, 28(3): 351-367.
5.	Starr AJ, Walter JC, Harris RW, et al. Percutaneous screw fixation of fractures of the iliac wing and fracture-dislocations of the sacro-iliac joint (OTA types 61-B2.2 and 61-B2.3, or young-burgess “lateral compression type II” pelvic fractures). J Orthop Trauma, 2002, 16(2): 116-123.
6.	Abdul-Jabbar A, Yilmaz E, Tubbs RS, et al. Neurovascular relationships of S2AI screw placement: Anatomic study. World Neurosurg, 2018, 116: e108-e112.
7.	Arora A, Berven S. Challenges and complications in freehand S2-Alar-Iliac spinopelvic fixation and the potential for robotics to enhance patient safety. Global Spine J, 2022, 12(2_suppl): 45S-52S.
8.	罗怡平, 张雷, 郑龙坡, 等. 机器人辅助经皮通道螺钉固定LC-Ⅱ型骨盆骨折的疗效研究. 中华骨科杂志, 2023, 43(19): 1261-1268.
9.	赵斌, 李金奇, 赵春鹏, 等. 基于5G技术的骨科机器人远程导航辅助植入经皮骨盆通道螺钉固定骨盆及髋臼骨折. 中国修复重建外科杂志, 2022, 36(8): 923-928.
10.	左楠, 杨光, 孙大辉, 等. 机器人辅助骶髂螺钉内固定联合LC-Ⅱ螺钉外固定治疗骨盆骨折. 中华骨科杂志, 2023, 43(19): 1269-1276.
11.	El Naga AN, Gendelberg D. Obturator inlet and iliac oblique technique for safe, convenient, and reliable iliac screw placement. N Am Spine Soc J, 2023, 17: 100298. doi: 10.1016/j.xnsj.2023.100298.
12.	Bishop JA, Routt ML. Osseous fixation pathways in pelvic and acetabular fracture surgery: osteology, radiology, and clinical applications. J Trauma Acute Care Surg, 2012, 72(6): 1502-1509.
13.	Lonstein JE, Denis F, Perra JH, et al. Complications associated with pedicle screws. J Bone Joint Surg (Am), 1999, 81(11): 1519-1528.
14.	Reichel LM, MacCormick LM, Dugarte AJ, et al. Minimally invasive anterior pelvic internal fixation: an anatomic study comparing pelvic bridge to INFIX. Injury, 2018, 49(2): 309-314.
15.	水小龙, 翁益民, 冯永增, 等. 经皮螺钉内固定治疗骨盆后方新月形骨折脱位. 中华创伤骨科杂志, 2015, 17(11): 921-925.
16.	Tian X, Li J, Sheng W, et al. Morphometry of iliac anchorage for transiliac screws: a cadaver and CT study of the Eastern population. Surg Radiol Anat, 2010, 32(5): 455-462.
17.	Alemdaroğlu KB, Yücens M, Kara T, et al. Pedicle axis view combined by sacral mapping can decrease fluoroscopic shot count in percutaneous iliosacral screw placement. Injury, 2014, 45(12): 1921-1927.
18.	Gras F, Hillmann S, Rausch S, et al. Biomorphometric analysis of ilio-sacro-iliacal corridors for an intra-osseous implant to fix posterior pelvic ring fractures. J Orthop Res, 2015, 33(2): 254-260.
19.	Öztürk V, Bilgili MG. Fluoroscopy-assisted identification of the individual optimal antegrade entry point of the anterior column fixation corridor in pelvic and acetabular surgery: a novel perspective. J Orthop Surg Res, 2025, 20(1): 635. doi: 10.1186/s13018-025-06027-0.
20.	邓京骐, 李涛, 朱振华, 等. 改良LC-Ⅱ螺钉固定钉道的数字化分析与验证. 中华老年骨科与康复电子杂志, 2023, 9(3): 129-137.

1. Hermans E, Edwards MJR, Goslings JC, et al. Open pelvic fracture: the killing fracture? J Orthop Surg Res, 2018, 13(1): 83. doi: 10.1186/s13018-018-0793-2.
2. Zhang BF, Shang K, Wang PF, et al. Comparison of posterior ring fixation with combined anterior and posterior ring fixation for the treatment of lateral compression type 2 pelvic fractures. Int Orthop, 2020, 44(6): 1187-1193.
3. Wu Y, Chen H, Zhou X, et al. Lateral compression type 2 pelvic fractures-a clinical study of fracture displacement measurement and closed reduction. Orthop Surg, 2022, 14(10): 2545-2552.
4. Simonian PT, Routt ML. Biomechanics of pelvic fixation. Orthop Clin North (Am), 1997, 28(3): 351-367.
5. Starr AJ, Walter JC, Harris RW, et al. Percutaneous screw fixation of fractures of the iliac wing and fracture-dislocations of the sacro-iliac joint (OTA types 61-B2.2 and 61-B2.3, or young-burgess “lateral compression type II” pelvic fractures). J Orthop Trauma, 2002, 16(2): 116-123.
6. Abdul-Jabbar A, Yilmaz E, Tubbs RS, et al. Neurovascular relationships of S2AI screw placement: Anatomic study. World Neurosurg, 2018, 116: e108-e112.
7. Arora A, Berven S. Challenges and complications in freehand S2-Alar-Iliac spinopelvic fixation and the potential for robotics to enhance patient safety. Global Spine J, 2022, 12(2_suppl): 45S-52S.
8. 罗怡平, 张雷, 郑龙坡, 等. 机器人辅助经皮通道螺钉固定LC-Ⅱ型骨盆骨折的疗效研究. 中华骨科杂志, 2023, 43(19): 1261-1268.
9. 赵斌, 李金奇, 赵春鹏, 等. 基于5G技术的骨科机器人远程导航辅助植入经皮骨盆通道螺钉固定骨盆及髋臼骨折. 中国修复重建外科杂志, 2022, 36(8): 923-928.
10. 左楠, 杨光, 孙大辉, 等. 机器人辅助骶髂螺钉内固定联合LC-Ⅱ螺钉外固定治疗骨盆骨折. 中华骨科杂志, 2023, 43(19): 1269-1276.
11. El Naga AN, Gendelberg D. Obturator inlet and iliac oblique technique for safe, convenient, and reliable iliac screw placement. N Am Spine Soc J, 2023, 17: 100298. doi: 10.1016/j.xnsj.2023.100298.
12. Bishop JA, Routt ML. Osseous fixation pathways in pelvic and acetabular fracture surgery: osteology, radiology, and clinical applications. J Trauma Acute Care Surg, 2012, 72(6): 1502-1509.
13. Lonstein JE, Denis F, Perra JH, et al. Complications associated with pedicle screws. J Bone Joint Surg (Am), 1999, 81(11): 1519-1528.
14. Reichel LM, MacCormick LM, Dugarte AJ, et al. Minimally invasive anterior pelvic internal fixation: an anatomic study comparing pelvic bridge to INFIX. Injury, 2018, 49(2): 309-314.
15. 水小龙, 翁益民, 冯永增, 等. 经皮螺钉内固定治疗骨盆后方新月形骨折脱位. 中华创伤骨科杂志, 2015, 17(11): 921-925.
16. Tian X, Li J, Sheng W, et al. Morphometry of iliac anchorage for transiliac screws: a cadaver and CT study of the Eastern population. Surg Radiol Anat, 2010, 32(5): 455-462.
17. Alemdaroğlu KB, Yücens M, Kara T, et al. Pedicle axis view combined by sacral mapping can decrease fluoroscopic shot count in percutaneous iliosacral screw placement. Injury, 2014, 45(12): 1921-1927.
18. Gras F, Hillmann S, Rausch S, et al. Biomorphometric analysis of ilio-sacro-iliacal corridors for an intra-osseous implant to fix posterior pelvic ring fractures. J Orthop Res, 2015, 33(2): 254-260.
19. Öztürk V, Bilgili MG. Fluoroscopy-assisted identification of the individual optimal antegrade entry point of the anterior column fixation corridor in pelvic and acetabular surgery: a novel perspective. J Orthop Surg Res, 2025, 20(1): 635. doi: 10.1186/s13018-025-06027-0.
20. 邓京骐, 李涛, 朱振华, 等. 改良LC-Ⅱ螺钉固定钉道的数字化分析与验证. 中华老年骨科与康复电子杂志, 2023, 9(3): 129-137.

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