Chinese Journal of Tissue Engineering Research ›› 2020, Vol. 24 ›› Issue (18): 2873-2878.doi: 10.3969/j.issn.2095-4344.2560

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Three-dimensional computed tomography evaluation of L5 pedicle screw fixation shielding by iliac wing width and height 

Zhang Shuai1, Ouyang Jianyuan1, Peng Xuelian2, Wang Song1, Wang Qing1   

  1. 1Department of Spinal Surgery, 2Department of Ultrasound, Affiliated Hospital of Southwest Medical University, Luzhou 646000, Sichuan Province, China
  • Received:2019-09-03 Revised:2019-09-05 Accepted:2019-10-19 Online:2020-06-28 Published:2020-04-03
  • Contact: Wang Qing, Master, Chief physician, Department of Spinal Surgery, Affiliated Hospital of Southwest Medical University, Luzhou 646000, Sichuan Province, China
  • About author:Zhang Shuai, Master, Physician, Department of Spinal Surgery, Affiliated Hospital of Southwest Medical University, Luzhou 646000, Sichuan Province, China Ouyang Jianyuan, Master candidate, Physician, Department of Spinal Surgery, Affiliated Hospital of Southwest Medical University, Luzhou 646000, Sichuan Province, China Zhang Shuai and Ouyang Jianyuan contributed equally to this paper.

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Abstract:

BACKGROUND: Previous scholars often graded the height of iliac spine according to X-ray films. The quality of X-ray images is greatly affected by the photographic equipment and position. Simultaneously, X-ray film transforms the three-dimensional relationship between the iliac wing and the L5 pedicle into a planar relationship. The overlap of bone structure makes it difficult to identify anatomic markers. Especially, the combination with osteoporosis, calcification of paravertebral artery, and stasis of intestinal contents in the elderly will further affect the observation of bone structure on X-ray films.

OBJECTIVE: To observe the degree of the entry point in L5 pedicle screw fixation shielded by the width and height of the iliac wing using the three-dimensional computed tomography reconstruction technique.

METHODS: According to the inclusion and exclusion criteria, 350 CT images of L1-S2 region were selected as the study object. All patients signed the informed consent. This study was approved by the Hospital Ethics Committee. The degree of the entry point in L5 pedicle screw fixation shielded by the width of the iliac wing in central axis layer of the horizontal axis was analyzed using the three-dimensional computed tomography reconstruction technique and divided into levels 0, I, II, and III. The degree of the entry point in L5 pedicle screw fixation shielded by the height of the iliac wing in central axis layer of the oblique sagittal plane was analyzed and also divided into levels 0, I, II, and III. Level 0 indicates that the entry point of L5 pedicle screw is not shielded by the iliac wing, and levels I, II, and III indicate increasing degrees of entry point of L5 pedicle screw shielding by the iliac wing. The difference in the effect of width and height of the iliac wing on the shielding degree of entry point in L5 pedicle screw was compared between males and females. 

RESULTS AND CONCLUSION: (1) In 80.0% of patients (280/350), the entry point of L5 pedicle screw was not shielded by the width of the iliac wing. In 20.0% (70/350) of patients, the entry point of L5 pedicle screw was shielded by the width of the iliac wing. In all, 27.3% (49/179) were male, including 27 with level I shielding, 14 with level II shielding, and 8 with level III shielding; 12.3% (21/171) were female, including 12 with level I shielding, 7 with level II shielding, and 2 with level III shielding. (2) In 80.6% (68/350) of patients, the entry point of L5 pedicle screw was not shielded by the height of the iliac wing. In 19.4% (68/350) of patients, the entry point of L5 pedicle screw was shielded by the height of the iliac wing. In all, 24.0% (43/179) of these patients were male, including 23 cases with level I shielding, 16 cases with level II shielding, and 4 with level III shielding; 14.6% (25/171) were female, including 13 with level I shielding, 8 with level II shielding, and 4 with level III shielding. (3) The degree of entry point of L5 pedicle screw shielding by the width of the iliac wing on the horizontal axis was not exactly the same as that of the height of the iliac wing on the sagittal axis of the L5 pedicle screw in the same patient. In this study, there were 70 patients with wide iliac wings and 68 patients with high iliac wings; the degrees of shielding by the width and height of the iliac wing were the same in 35 cases and different in 44 cases. (4) The degree of entry point of L5 pedicle screw shielding by the width and height of the iliac wing was greater in males than in females. (5) The results confirmed that the incidence of entry point of L5 pedicle screw shielding by the iliac wing width and height was 20.0% and 19.4%, respectively. The degree of entry point of L5 pedicle screw shielding by the width and height of the iliac wing was greater in males than females. The degree of entry point of L5 pedicle screw shielding by the iliac wing width along the horizontal axis was not completely consistent with that of L5 pedicle screw shielding on the oblique sagittal plane. It is of great significance to evaluate the relationship between iliac wing and L5 pedicle screw entry point by three-dimensional computed tomography reconstruction before operation for improving the safety of L5 pedicle screw placement and decision-making of operation.

Key words: iliac wing width, iliac wing height, L5 pedicle screw, three-dimensional computed tomography reconstruction, shielding

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