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. 2025 Aug 27.
doi: 10.1007/s43390-025-01152-6. Online ahead of print.

Behavior of the un-instrumented lumbar curve following exclusive tethering of the thoracic region

Ritt R Givens  1   2 , Matan S Malka  3 , Christina Carin Rymond  3 , Kevin Lu  3 , Firoz Miyanji  4 , Juan Carlos Rodriguez  5 , Kevin Smit  6 , Ron El-Hawary  7 , Stefan Parent  8 , Walter Huu Truong  9 , Michelle C Welborn  10 , Michael G Vitale  3 ; Pediatric Spine Study Group
Affiliations

Behavior of the un-instrumented lumbar curve following exclusive tethering of the thoracic region

Ritt R Givens et al. Spine Deform. .

Abstract

Introduction: Anterior vertebral body tethering (AVBT) has recently been utilized as a surgical alternative to posterior spinal fusion for a subset of pediatric scoliosis patients. Indications for AVBT are evolving and, while early results have been promising, there is a paucity of literature examining the behavior of the lumbar curve after exclusive tether of the thoracic region. It was hypothesized that thoracic tether leads to a spontaneous decrease in the un-instrumented lumbar curve.

Methods: The study population consisted of 166 patients with idiopathic scoliosis enrolled in the Pediatric Spine Study Group registry undergoing thoracic tether with a minimum of two-year follow-up. Exclusion criteria included: patients with non-idiopathic scoliosis, patients with prior spine surgery, and patients instrumented below L1.

Results: Overall curve correction was notable, with mean pre-op, immediate post-op, and two-year follow-up angles of 51.3°, 29.7°, and 30.3° respectively for the thoracic curve and 32.7°, 22.9°, and 24.1° respectively for the un-instrumented lumbar curve. Overall, 124 subjects (74.7%) had a decrease in lumbar curve > 5° immediately post-op. Over a two-year follow-up period, 32 subjects (19%) had a continued decrease in lumbar curve > 5°, 91 subjects (54%) had minimal change, and 43 subjects (26%) had an increase in lumbar curve > 5°. In a subgroup analysis of 36 subjects with a decrease in thoracic curve > 5° from post-op to two-year follow-up, 11 subjects (31%) had a concomitant decrease in lumbar curve with only 5 (14%) showing an increase in lumbar curve > 5°. The changes in lumbar curve from pre-op to post-op and from post-op to two-year follow-up were found to be associated with changes in the thoracic curve for the same periods (rho = 0.603, p < 0.001; rho = 0.413, p < 0.001 respectively). When considering Lenke lumbar modifiers, the un-instrumented lumbar curve corrected an average of 35%, 27%, and 20% following surgery and 27%, 30%, and 17% at two-year follow-ups for A, B, and C curves respectively (p < .001 for all data points compared to pre-op).

Conclusion: Lumbar curves tended to mirror the behavior of the maximal thoracic curve in terms of correction or decompensation both during surgery and during the two-year follow-up. Furthermore, un-instrumented lumbar curves with a Lenke C modifier tended to achieve a lower percentage correction. These data provide clearer insights into the response of the lumbar curve following thoracic tethering and the effect of growth modulation.

Keywords: Anterior vertebral body tethering; Idiopathic scoliosis; Lumbar curve behavior.

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Conflict of interest statement

Declarations. Conflict of interest: RRG has no conflicts of interest to disclose. MSM has no conflicts of interest to disclose. CCR has no conflicts of interest to disclose. KL has no conflicts of interest to disclose. FM is a paid consultant for Depuy Synthes Spine, Zimvie, Orthopediatrics, and Biederman Motec. He is an advisory committee member for the AO Fracture, Tumor, Deformity Expert Group. JCR is a consultant for Globus Medical. KS has received institutional research support from Medtronic, SpinoModulation, and Ascendis. REH is a board member of the Pediatric Spine Foundation and Scoliosis Research Society. He has received research support from DePuy, Medtronic, and Zimmer. He is a paid consultant for Orthopediatrics and receives publishing royalties from Springer. SP has received royalties from EOS imaging. He is Co-founder of the company Spinologics Inc. He received consultancy fees from DePuy Synthes Spine and received grants from DePuy Synthes Spine, Canadian Institutes of Health Research, Pediatric Orthopaedic Society of North America, Scoliosis Research Society, Medtronic, EOS imaging, Setting Scoliosis Straight Foundation, and Fonds de recherche Québec – Santé. He received fellowship support from DePuy Synthes, Orthopediatrics, and Medtronic and is the holder of the Academic Chair in Pediatric Spinal Deformities of CHU Ste-Justine. He is a member of speaker bureau of Orthopaediatrics. WT has no disclosures. MCW has served on the advisory board for Orthofix, Nuvasive/Globus, Orthopediatrics, and Astrazenica. She has served on the editorial board for JPO, Spine, and Spine Deformity. She has received grants from the Pediatric Spine Study Group and Shriner’s Children’s. MGV has received grants from the Pediatric Orthopaedic Society of North America, Orthopedic Science Research Foundation, Pediatric Spine Foundation, and Setting Scoliosis Straight Foundation and royalties from Biomet. He is a paid consultant for Stryker, Biomet, and NuVasive. MGV is on the Board of Directors of Pediatric Spine Foundation, Pediatric Spine Study Group, and C4K. He is former president of Pediatric Orthopaedic Society of North America and is a Board Member, Chair Emeritus of the International Pediatric Orthopaedic Symposium. PSSG is supported by the Pediatric Spine Foundation (PSF). PSF receives research funding from: JNJ Medtech, Globus, OrthoPediatrics, Highridge Medical. PSSG receives educational support from: Highridge Medical, JNJ Medtech, OrthoPediatrics, Medtronic, Globus, nView Medical, Stryker, Atec, Momentum Health, MRIGuidance, SpineGuard. Ethics approval: This study was approved by the Columbia University Institutional Review Board under protocol AAAB5378. It was performed in accordance with the ethical standards of the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. All included cases were in accordance with the Spine Deformity submission guidelines. Consent to participate: Informed consent was waived for participants included in this study. Consent for publication: No patient-identifying information is included in the article. Not applicable.

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