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. 2023 Sep 4;7(6):540-546.
doi: 10.22603/ssrr.2023-0134. eCollection 2023 Nov 27.

Wedge-Shaped Deformity of the First Sacral Vertebra Associated with Adolescent Idiopathic Scoliosis: A Comparison of Cases with and without Scoliosis

Ippei Yamauchi  1 , Hiroaki Nakashima  1 , Sadayuki Ito  1 , Naoki Segi  1 , Jun Ouchida  1 , Ryoji Tauchi  2 , Tetsuya Ohara  2 , Noriaki Kawakami  3 , Shiro Imagama  1
Affiliations

Wedge-Shaped Deformity of the First Sacral Vertebra Associated with Adolescent Idiopathic Scoliosis: A Comparison of Cases with and without Scoliosis

Ippei Yamauchi et al. Spine Surg Relat Res. .

Abstract

Introduction: Scoliosis is the three-dimensional (3D) deformity of the spine. Scoliosis curvatures, such as the lower lumbar curve and the angle of the upper endplate of the sacrum observable on radiographs, are associated with postoperative outcomes; however, the relationship between postoperative outcomes and sacral morphology remains unknown. This study aimed to investigate sacral morphology in patients with adolescent idiopathic scoliosis (AIS) and to clarify its relationship with wedge-shaped deformity of the first sacral vertebra and radiographic parameters.

Methods: This study included 94 patients who underwent fusion surgery for AIS (scoliosis group). As the control group, 25 patients without scoliosis (<10°) under 50 years of age were also investigated. S1 wedging angle (S1WA) using 3D Computed tomography (CT) and Cobb angle, L4 tilt, and sacral slanting using radiography were measured. The relationship between S1WA and other radiographic parameters was analyzed using correlation coefficients. Differences in sacral morphology between the Lenke lumbar modifier types A and C were also investigated.

Results: S1WA was significantly larger in the scoliosis group than the control group (scoliosis: 1.7°±2.5°, control: 0.1°±1.5°, p=0.002). Furthermore, the number of patients with S1WA >3° or >5° was significantly higher in the scoliosis group (>3°: 33%, 8%, p=0.012; >5°: 16%, 0%, p=0.039). S1WA correlated with sacral slanting (r=0.45, p<0.001) and L4 tilt (r=0.35, p<0.001) and was significantly greater with Lenke lumbar modifier C than A (2.4°±2.6°, 0.8°±2.0°; p<0.001).

Conclusions: The S1 vertebra was deformed and wedge-shaped in AIS, especially in cases with a large lumbar curve. Additionally, S1WA is associated with sacral slanting and L4 tilt on radiography in AIS.

Keywords: Adolescent idiopathic scoliosis; Computed tomography; Deformity; Morphology; Sacral slanting; Sacrum.

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Conflict of interest statement

Conflicts of Interest: The authors declare that there are no relevant conflicts of interest.

Figures

Figure 1.
Figure 1.
Flowchart of the retrospective study design.
Figure 2.
Figure 2.
S1 wedging angle. The S1 wedging angle (S1WA) is the angle between the S1 superior endplate and the line parallel to the intervertebral disc between S1 and S2.
Figure 3.
Figure 3.
Representative scoliosis radiographs and 3DCT images.
See this image and copyright information in PMC

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