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ArticleEuropean spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society2025

A mathematical model for estimating the intraoperative lowest instrumented vertebra (LIV) tilt angle using preoperative supine left side-bending (LSB) radiographs in adolescent idiopathic scoliosis (AIS) patients with lenke type 1 and 2 non-AR curves.

Mun Keong Kwan, Sin Ying Lee, Sze Khiong Fam, Yee Wern Evonne Tan, Chun Hong Ngan, Saturveithan Chandirasegaran, Chee Kidd Chiu, Chris Yin Wei Chan

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Article in European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

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1 · What the graph read from it

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3 · Its place in the literature

Who cites it

2 citing papers in PubMed.

  1. Factors associated with transfusion and surgical site infection following paediatric scoliosis surgery: insights from a Latin American retrospective cohort.European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society · 2026
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5 · Who and what money

Authors and funding

8 authors.

Mun Keong KwanDepartment of Orthopaedic Surgery, Faculty of Medicine, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Universiti Malaya, 50603, Kuala Lumpur, Malaysia. munkeong42@hotmail.com.ORCID 0000-0002-9512-3155
Sin Ying LeeDepartment of Orthopaedic Surgery, Faculty of Medicine, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
Sze Khiong FamDepartment of Orthopaedic Surgery, Faculty of Medicine, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
Yee Wern Evonne TanDepartment of Orthopaedic Surgery, Faculty of Medicine, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
Chun Hong NganDepartment of Orthopaedic Surgery, Faculty of Medicine, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
Saturveithan ChandirasegaranDepartment of Orthopaedic Surgery, Faculty of Medicine, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
Chee Kidd ChiuDepartment of Orthopaedic Surgery, Faculty of Medicine, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
Chris Yin Wei ChanDepartment of Orthopaedic Surgery, Faculty of Medicine, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Universiti Malaya, 50603, Kuala Lumpur, Malaysia.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeTo devise a mathematical model for estimating the intraoperative lowest instrumented vertebra (LIV) tilt angle using preoperative supine left side-bending (LSB) radiographs in adolescent idiopathic scoliosis (AIS) patients with Lenke type 1 and 2 (non-AR curves), and to review its clinical and radiological outcomes.

methodsThe mathematical model for the adjusted LSB LIV tilt angle (α) measured preoperatively, was expressed as the sum of preoperative LSB LIV tilt angle (x) and LIV displacement angle (y) (α = x + y). This model was validated through inter-rater and intra-rater analysis in Part I of the study. The α angle derived was applied to estimate the intraoperative LIV tilt angle. In part II of the study, clinical and radiological outcomes of 50 Lenke type 1 and 2 (non-AR curves) AIS patients operated using the α angle were reviewed. The difference between the intraoperative LIV tilt angle achieved (β) and the preoperative α angle was determined (∆LIV tilt angle = β-α).

resultsThe α angle had excellent inter-rater and intra-rater intraclass correlation coefficients (0.982; 0.907). 42 patients had positive ∆LIV tilt angles whereas 8 patients had negative ∆LIV tilt angles. The overall incidence of distal adding-on (AO) was 10.0% (n = 5/50). Patients with negative ∆LIV tilt angles had a higher incidence of distal AO (n = 4/8, 50.0%) than patients with positive ∆LIV tilt angles (n = 1/42, 2.4%) (p = 0.001).

conclusionAchieving an intraoperative LIV tilt angle (β) greater than or equal to the preoperative α angle derived (β ≥ α) may help avoid the distal AO phenomenon.

Indexed as

Lumbar VertebraeModels, TheoreticalScoliosisSpinal FusionThoracic VertebraeAdolescentChildFemaleHumansMaleRadiographySupine PositionAdolescent idiopathic scoliosisDistal adding-onLenke 1Lenke 2LIV tilt angle

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.