Brink RC, Schlösser TPC, Colo D, Vincken KL, van Stralen M, Hui SCN, Chu WCW, Cheng JCY, Castelein RM. Asymmetry of the Vertebral Body and Pedicles in the True Transverse Plane in Adolescent Idiopathic Scoliosis: A CT-Based Study.
Spine Deform 2017;
5:37-45. [PMID:
28038692 DOI:
10.1016/j.jspd.2016.08.006]
[Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 08/10/2016] [Indexed: 11/25/2022]
Abstract
STUDY DESIGN
Cross-sectional.
OBJECTIVES
To quantify the asymmetry of the vertebral bodies and pedicles in the true transverse plane in adolescent idiopathic scoliosis (AIS) and to compare this with normal anatomy.
SUMMARY OF BACKGROUND DATA
There is an ongoing debate about the existence and magnitude of the vertebral body and pedicle asymmetry in AIS and whether this is an expression of a primary growth disturbance, or secondary to asymmetrical loading.
METHODS
Vertebral body asymmetry, defined as left-right overlap of the vertebral endplates (ie, 100%: perfect symmetry, 0%: complete asymmetry) was evaluated in the true transverse plane on CT scans of 77 AIS patients and 32 non-scoliotic controls. Additionally, the pedicle width, length, and angle and the length of the ideal screw trajectory were calculated.
RESULTS
Scoliotic vertebrae were on average more asymmetric than controls (thoracic: AIS 96.0% vs. controls 96.4%; p = .005, lumbar: 95.8% vs. 97.2%; p < .001) and more pronounced around the thoracic apex (95.8%) than at the end vertebrae (96.3%; p = .031). In the thoracic apex; the concave pedicle was thinner (4.5 vs. 5.4 mm; p < .001) and longer (20.9 vs. 17.9 mm; p < .001), the length of the ideal screw trajectory was longer (43.0 vs. 37.3 mm; p < .001), and the transverse pedicle angle was greater (12.3° vs. 5.7°; p < .001) than the convex one. The axial rotation showed no clear correlation with the asymmetry.
CONCLUSIONS
Even in non-scoliotic controls is a degree of vertebral body and pedicle asymmetry, but scoliotic vertebrae showed slightly more asymmetry, mostly around the thoracic apex. In contrast to the existing literature, there is no major asymmetry in the true transverse plane in AIS and no uniform relation between the axial rotation and vertebral asymmetry could be observed in these moderate to severe patients, suggesting that asymmetrical vertebral growth does not initiate rotation, but rather follows it as a secondary phenomenon.
LEVEL OF EVIDENCE
Level 4.
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