Guidance for dysmorphic sacrum fixation with upper sacroiliac screw based on imaging anatomy study: techniques and indications

Tan Shan; Li Hanqing; Ai Qiuchi; Xing Junchao; Xu Meitao; Gao Shichang; Hou Tianyong

doi:10.1186/s12891-023-06655-9

Guidance for dysmorphic sacrum fixation with upper sacroiliac screw based on imaging anatomy study: techniques and indications

BMC Musculoskelet Disord. 2023 Jun 30;24(1):536. doi: 10.1186/s12891-023-06655-9.

Authors

Tan Shan¹, Li Hanqing¹, Ai Qiuchi¹, Xing Junchao¹, Xu Meitao¹, Gao Shichang², Hou Tianyong³

Affiliations

¹ Department of Orthopedics, the First Affiliated Hospital of Army Medical University, Chongqing, China.
² Department of Orthopedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China. 778925053@qq.com.
³ Department of Orthopedics, the First Affiliated Hospital of Army Medical University, Chongqing, China. tianyonghou@126.com.

Abstract

Objective: This study aimed to investigate the techniques and indications of upper sacroiliac screw fixation for the dysmorphic sacrum.

Methods: The dysmorphic sacra were selected from 267 three-dimensional pelvic models. The dysmorphic sacra which couldn't accommodate a 7.3 mm upper trans ilio-sacroiliac screw were classified as the main dysmorphic sacra. Then, the size of the bone corridor, the length of the screw in the corridor, and the orientation of the screw were measured. The insertion point on the sacrum was identified by two bone landmarks.

Results: totally, 30.3% of sacra were identified as the main dysmorphic sacra. The inclinations of the screw oriented from posterior to anterior were (21.80 ± 3.56)° for males and (19.97 ± 3.02)° for females (p < 0.001), and from caudal to cranial were (29.97 ± 5.38)° for males and (28.15 ± 6.21)° for females (p = 0.047). The min diameters of the corridor were (16.31 ± 2.40) mm for males and (15.07 ± 1.58) mm for females (p < 0.001). The lengths of the screw in the Denis III zone were (14.41 ± 4.40) mm for males and (14.09 ± 5.04) mm for females (p = 0.665), and in the Denis II+III zones were (36.25 ± 3.40) mm for males and (38.04 ± 4.60) mm for females (p = 0.005). The rates of LP-PSIS/LAIIS-PSIS were (0.36 ± 0.04) for males and (0.32 ± 0.03) for females (t = 4.943, p < 0.001). The lengths of LPM were (8.81 ± 5.88) for males and (-4.13 ± 6.33) for females (t = 13.434, p < 0.001).

Conclusion: When the sacrum has the features of "sacrum not recessed" and/or "acute alar slope", the conventional trans ilio-sacroiliac screw couldn't be placed safely. The inclination oriented from posterior to anterior and from caudal to cranial are approximately 20° and 30°, respectively. The bone insertion point locates in the rear third of the anterior inferior iliac spine to the posterior superior iliac spine. The sacroiliac screw is not recommended to fix the fractures in Denis III zone.

Keywords: Dysmorphic sacrum; Imaging anatomy; Sacral fracture; Sacroiliac screw.

MeSH terms

Bone Screws
Diagnostic Imaging
Female
Fractures, Bone*
Humans
Male
Pelvis
Sacrum* / diagnostic imaging
Sacrum* / surgery