Are insufficient corrections a major factor in distal junctional kyphosis? A simulated analysis of cervical deformity correction using in-construct measurements.

Abstract

Objective

The present study utilized recently developed in-construct measurements in simulations of cervical deformity surgery in order to assess undercorrection and predict distal junctional kyphosis (DJK).

Methods

A retrospective review of a database of operative cervical deformity patients was analyzed for severe DJK and mild DJK. C2-lower instrumented vertebra (LIV) sagittal angle (SA) was measured postoperatively, and the correction was simulated in the preoperative radiograph in order to match the C2-LIV by using the planning software. Linear regression analysis that used C2 pelvic angle (CPA) and pelvic tilt (PT) determined the simulated PT that matched the virtual CPA. Linear regression analysis was used to determine the C2-T1 SA, C2-T4 SA, and C2-T10 SA that corresponded to DJK of 20° and cervical sagittal vertical axis (cSVA) of 40 mm.

Results

Sixty-nine cervical deformity patients were included. Severe and mild DJK occurred in 11 (16%) and 22 (32%) patients, respectively; 3 (4%) required DJK revision. Simulated corrections demonstrated that severe and mild DJK patients had worse alignment compared to non-DJK patients in terms of cSVA (42.5 mm vs 33.0 mm vs 23.4 mm, p < 0.001) and C2-LIV SVA (68.9 mm vs 57.3 mm vs 36.8 mm, p < 0.001). Linear regression revealed the relationships between in-construct measures (C2-T1 SA, C2-T4 SA, and C2-T10 SA), cSVA, and change in DJK (all R > 0.57, p < 0.001). A cSVA of 40 mm corresponded to C2-T4 SA of 10.4° and C2-T10 SA of 28.0°. A DJK angle change of 10° corresponded to C2-T4 SA of 5.8° and C2-T10 SA of 20.1°.

Conclusions

Simulated cervical deformity corrections demonstrated that severe DJK patients have insufficient corrections compared to patients without DJK. In-construct measures assess sagittal alignment within the fusion separate from DJK and subjacent compensation. They can be useful as intraoperative tools to gauge the adequacy of cervical deformity correction.

Department

Description

Provenance

Subjects

Cervical Vertebrae, Humans, Kyphosis, Treatment Outcome, Spinal Fusion, Retrospective Studies, Adult, Aged, Middle Aged, Female, Male

Citation

Published Version (Please cite this version)

10.3171/2023.12.spine23481

Publication Info

Ani, Fares, Ethan Sissman, Dainn Woo, Alex Soroceanu, Gregory Mundis, Robert K Eastlack, Justin S Smith, D Kojo Hamilton, et al. (2024). Are insufficient corrections a major factor in distal junctional kyphosis? A simulated analysis of cervical deformity correction using in-construct measurements. Journal of neurosurgery. Spine, 40(5). pp. 622–629. 10.3171/2023.12.spine23481 Retrieved from https://hdl.handle.net/10161/31236.

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Scholars@Duke

Passias

Peter Passias

Instructor in the Department of Orthopaedic Surgery

Throughout my medical career, I have remained dedicated to improving my patients' quality of life. As a specialist in adult cervical and spinal deformity surgery, I understand the significant impact our interventions have on individuals suffering from debilitating pain and physical and mental health challenges. Spinal deformity surgery merges the complexities of spinal biomechanics with the needs of an aging population. My research focuses on spinal alignment, biomechanics, innovative surgical techniques, and health economics to ensure value-based care that enhances patient outcomes.


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