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. 2025 Mar;15(2):1200-1211.
doi: 10.1177/21925682241230964. Epub 2024 Feb 6.

Pedicle Dysplasia in Proximal Thoracic Adolescent Idiopathic Scoliosis Curves: What are We Missing and What are its Possible Surgical Implications? An Observational Retrospective Study on 104 Patients

Giovanni Viroli  1 , Alberto Ruffilli  1 , Francesca Barile  1 , Marco Manzetti  1 , Matteo Traversari  1 , Cesare Faldini  1
Affiliations

Pedicle Dysplasia in Proximal Thoracic Adolescent Idiopathic Scoliosis Curves: What are We Missing and What are its Possible Surgical Implications? An Observational Retrospective Study on 104 Patients

Giovanni Viroli et al. Global Spine J. 2025 Mar.

Abstract

Study design: Retrospective cohort study.

Objectives: To assess if pedicle dysplasia is present in proximal thoracic (PT), both structural and nonstructural, compared to main thoracic (MT) curves; and to assess if it is predictive of radiographic outcomes at minimum 2 years of follow-up.

Methods: A retrospective review of surgically-treated Adolescent Idiopathic Scoliosis (AIS) patients with Lenke 1-2-3-4 curves was performed. On preoperative CT-scan, at the apical vertebra, pedicle width on the concavity (PWc) and on the convexity (PWv) and Pedicle Dysplasia Index (PDI, defined as PWc/PWv) were measured. Preoperative and last follow-up (at least 2 years) x-rays were reviewed.

Results: 104 patients meeting the inclusion criteria were divided into Structural-PT (S-PT) and Nonstructural-PT (NS-PT) groups based on Lenke criteria. PWc (P < .001). And PDI (P < .001 for S-PT, P = .004 for NS-PT) were significantly smaller in the PT than in MT curves for both groups. PT-PWc significantly correlated with follow-up PT Cobb for both groups (P < .001 and P = .015 respectively). PT-PDI significantly correlated with follow-up PT-Cobb (P < .001), CA (P < .040) and T1 tilt (P < .002), only for NS-PT group. NS-PT patients with PWc PT <1 mm had higher RSHD (P = .021) and T1 tilt (P = .025) at follow-up. NS-PT patients with PDI PT <.3 had higher RSHD (P < .001), CA (P = .002) and T1 tilt (P = .003) at follow-up.

Conclusion: S-PT and NS-PT curves show significant pedicle dysplasia on the concavity. Pedicle dysplasia significantly correlated with shoulder balance at follow-up, for NS-PT patterns. Patients with a PWc <1 mm or PDI <.30 are at particular risk of postoperative shoulder imbalance.

Keywords: adolescent idiopathic scoliosis; lenke classification; pedicle dysplasia; proximal curve; shoulder balance; shoulder imbalance.

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Conflict of interest statement

Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

Figures

Figure 1.
Figure 1.
Exemplificative case. (A): Preoperative radiographic appearance of a 20 years old female patient with a 59° main thoracic curve. The side bending and lateral films, reveal the unstructural nature of the proximal thoracic and of the lumbar curves (B): Axial CT-scan of apical vertebra of the PT curve (T1, left) and of the MT curve (T7, right). In blue, the pedicle axis, in red the PW (pedicle width). It can be noted the severe pedicle dysplasia in the PT curve (PWc = 0,4 mm; PWv = 2,8 mm) and the moderate dysplasia in the MT curve (PWc = 2,4; PWv = 2,9 mm).
Image 1.
Image 1.
(A and B) Correlation plots between PWc (2A), PDI (2B) and shoulder balance parameters (Radiographic Shoulder Height Difference, Clavicular Angle, T1 Tilt) for Nonstructural PT group.
Image 2.
Image 2.
(A and B) Correlation plots between PWc (3A), PDI (3B) and shoulder balance parameters (Radiographic Shoulder Height Difference, Clavicular Angle, T1 Tilt) for Structural PT group.
See this image and copyright information in PMC

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