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Morphometric Characteristics of Sacral-2 Alar Iliac Screw Fixation in Pediatric Population

Shen, Zhi-Hao, MD∗,†; Wang, Kai, MD; Chen, Dong, MD; Zheng, Xuan-Qi, MD; Huang, Jin-Feng, MD; Wu, Ai-Min, MD, PhD

doi: 10.1097/BRS.0000000000002916
ANATOMY
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Study Design. A computed tomographic assessment.

Objective. To establish morphometric data of sacral-2 alar iliac (S2AI) screw fixation in pediatric population.

Summary of Background Data. Studies on morphometric parameters of S2AI screw fixation are mostly based on adult population. The pediatric scoliosis also needs the S2AI screw fixation, however, without the previous morphometric information of among pediatric population.

Methods. Computed tomography (CT) scans of 120 pediatric patients without spinal deformities are obtained and imported to Mimics software for 3D reconstruction. Then, a cylinder (radius of 3.25 mm) is drawn to imitate the screw trajectory of S2AI screw and adjusted to a maximum upward and downward angle to obtain the feasible region. Nine parameters of the S2AI screw are measured. Differences between age groups are compared and significant statistical correlations are carefully studied to determine the potentially important clinical relationships.

Results. The mean values and standard deviations (SD) for nine parameters at the maximum upward and downward angles were determined. With age increased, the S2AI screw trajectory becomes more caudal in the coronal (44.03 ± 4.43°–53.15 ± 4.68°) and sagittal planes (50.33 ± 5.89°–57.69 ± 4.21°) and more lateral in the transverse plane (49.40 ± 5.90°–54.44 ± 2.99°), and all of the distance parameters include max-length, sacral distance, iliac width, S2 midline, iliac wing, and skin distance increased. Age has a more significant effect on other parameters than transverse angle and skin distance (P < 0.05).

Conclusion. The S2AI screw fixation could be used on pediatric population too, but the pediatric population had smaller size of pelvis than adults, surgeons should choose the smaller diameters and the shorter length of screws for pediatric population depends on their age.

Level of Evidence: N/ A

We obtained computed tomography scans of 120 pediatric patients without spinal deformities to reconstruct their pelvis in three-dimension, and established sacral-2 alar iliac (S2AI) morphological data of S2AI screw fixation in pediatric population. It can provide surgeons a referential specification of S2AI screw for pediatric population depends on their age.

Department of Spine Surgery, Zhejiang Spine Surgery Centre, Orthopaedic Hospital, The Second Affiliated Hospital and Yuying Children's Hospital of the Wenzhou Medical University, Wenzhou, Zhejiang

The First Clinical College, Hainan Medical University, Haikou, Hainan, China.

Address correspondence and reprint requests to Ai-Min Wu, MD, PhD, Department of Spine Surgery, Zhejiang Spine Surgery Centre, Orthopaedic Hospital, The Second Affiliated Hospital and Yuying Children's Hospital of the Wenzhou Medical University, 109# Xueyuan Road, Wenzhou, Zhejiang 325027, China; E-mail: aiminwu@wmu.edu.cn

Received 13 June, 2018

Revised 15 August, 2018

Accepted 3 October, 2018

The manuscript submitted does not contain information about medical device(s)/drug(s).

The Wenzhou Municipal Science and Technology Bureau (Y20170389), Wenzhou leading talent innovative project (RX2016004), National Natural Science Foundation of China (81501933), and Zhejiang Provincial Medical Technology Foundation of China (2018KY129) funds were received in support of this work.

No relevant financial activities outside the submitted work.

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