Elsevier

World Neurosurgery

Volume 112, April 2018, Pages e61-e68
World Neurosurgery

Original Article
Drivers of Cervical Deformity Have a Strong Influence on Achieving Optimal Radiographic and Clinical Outcomes at 1 Year After Cervical Deformity Surgery

https://doi.org/10.1016/j.wneu.2017.12.024Get rights and content

Objective

The primary driver (PD) of cervical malalignment is important in characterizing cervical deformity (CD) and should be included in fusion to achieve alignment and quality-of-life goals. This study aims to define how PDs improve understanding of the mechanisms of CD and assesses the impact of driver region on realignment/outcomes.

Methods

Inclusion: radiographic CD, age >18 years, 1 year follow-up. PD apex was classified by spinal region: cervical, cervicothoracic junction (CTJ), thoracic, or spinopelvic by a panel of spine deformity surgeons. Primary analysis evaluated PD groups meeting alignment goals (by Ames modifiers cervical sagittal vertical axis/T1 slope minus cervical lordosis/chin-brow vergical angle/modified Japanese Orthopaedics Association questionnaire) and health-related quality of life (HRQL) goals (EuroQol–5 Dimensions questionnaire/Neck Disability Index/modified Japanese Orthopaedics Association questionnaire) using t tests. Secondary analysis grouped interventions by fusion constructs including the primary or secondary apex based on lowest instrumented vertebra: cervical, lowest instrumented vertebra (LIV) ≤C7; CTJ, LIV ≤T3; and thoracic, LIV ≤T12.

Results

A total of 73 patients (mean age, 61.8 years; 59% female) were evaluated with the following PDs of their sagittal cervical deformity: cervical, 49.3%; CTJ, 31.5%; thoracic, 13.7%; and spinopelvic, 2.7%. Cervical drivers (n = 36) showed the greatest 1-year postoperative cervical and global alignment changes (improvement in T1S, CL, C0-C2, C1 slope). Thoracic drivers were more likely to have persistent severe T1 slope minus cervical lordosis modifier grade at 1 year (0, 20.0%; +, 0.0%; ++, 80.0%). Cervical deformity modifiers tended to improve in cervical patients whose construct included the PD apex (included, 26%; not, 0%; P = 0.068). Thoracic and cervicothoracic PD apex patients did not improve in HRQL goals when PD apex was not treated.

Conclusions

CD structural drivers have an important effect on treatment and 1-year postoperative outcomes. Cervical or thoracic drivers not included in the construct result in residual deformity and inferior HRQL goals. These factors should be considered when discussing treatment plans for patients with CD.

Introduction

As the literature surrounding surgical treatment of cervical deformity (CD) has expanded in recent years, so too has the systematic classification of CD type, apex, and impact on health-related quality of life (HRQL).1, 2 The development of the Ames Adult Cervical Deformity (Ames-ACD) classification system has provided a framework for the categorization of CD based on radiographic, anatomic, and clinical presentation.2 Using 5 deformity descriptors, the Ames-ACD system differentiates CD type by the sagittal apex of the deformity, creating a common language for patient–physician communication, and surgical planning.3, 4, 5, 6, 7 Despite advances in the classification of CD, there are a lack of studies investigating the structural drivers of cervical sagittal malalignment and their importance in the characterization of CD.

Several studies have underscored the interdependent relationship of the cervical, thoracolumbar, and lumbopelvic spinal regions in the context of CD.8, 9, 10 The wide-ranging clinical and radiographic presentations of CD reflect the varied structural causes of the disease, which can extend below the cervical curve into the thoracic and lumbopelvic spine. A recent study showed significant differences in preoperative and postoperative sagittal alignment across groups of patients with CD drivers in the cervical, cervicothoracic, thoracic, and lumbopelvic regions, highlighting both driver location and driver inclusion in surgery as important considerations in preoperative planning.11 Although an important contribution to the literature surrounding CD-corrective surgery, the study focused only on primary, as opposed to secondary, drivers of CD and was limited to short-term, 3-month postoperative clinical and radiographic follow-up.

There is a paucity in the literature regarding the relationship between different structural causes of CD and patient HRQL outcomes. The present study investigates how both primary and secondary CD drivers affect postoperative sagittal alignment and assesses the long-term clinical impact of driver region and driver inclusion in surgery.

Section snippets

Data Source

This study is a retrospective review of a prospective, multicenter database of consecutive patients with CD enrolled from 2012 to 2015. Patients were enrolled at 13 spine centers across the United States, and institutional review board approval was obtained from all participating centers before study initiation. Included in the database were patients ≥18 years old with radiographic evidence of CD, as defined by the presence of at least 1 of the following on baseline imaging: cervical kyphosis

Study Cohort Overview

Seventy-three patients underwent CD-corrective surgery (mean age, 61.8 ± 10.7 years; mean body mass index, 29.5 ± 8.1 kg/m2; 59% female). The distribution of primary cervical drivers by spinal region was as follows: cervical, 36 (49.3%); cervicothoracic junction, 23 (31.5%); thoracic, 10 (13.7%); spinopelvic, 2 (2.7%); and coronal, 2 (2.7%). Differences between PD groups with respect to baseline demographics, comorbidity burden, and surgical information are outlined in Table 1. Overall baseline

Discussion

Accurate assessment of CD requires clinical and radiographic evaluation in the context of the whole spine. Although CD can result from congenital cervical malalignment, compensatory cervical malalignment has frequently been associated with deformity in subjacent spinal segments and inferior HRQL.15, 16, 17, 18, 19 Effective surgical planning for primary CD must take into account structural drivers of deformity that are both within and below the cervical spine. This study aimed to assess the

Conclusions

In a population of 73 prospectively collected consecutive patients undergoing CD-corrective surgery, structural drivers of CD were identified in both the coronal plane and the cervical, cervicothoracic, thoracic, and spinopelvic sagittal curves. Deformity driver location played an important role in postoperative radiographic and clinical outcomes, with patients with cervical PD showing the least amount of residual sagittal deformity at 1 year, and patients with upper-thoracic/cervical secondary

References (24)

  • T. Oh et al.

    Cervical compensatory alignment changes following correction of adult thoracic deformity: a multicenter experience in 57 patients with a 2-year follow-up

    J Neurosurg Spine

    (2015)
  • Passias PG, Jalai CM, Lafage V, Lafage R, Protopsaltis T, Ramchandran S, et al. Primary drivers of adult cervical...
  • Cited by (22)

    • Intraoperative alignment goals for distinctive sagittal morphotypes of severe cervical deformity to achieve optimal improvements in health-related quality of life measures

      2020, Spine Journal
      Citation Excerpt :

      Tang et al. demonstrated that positive cervical sagittal vertical axis (cSVA) was associated with worse outcomes after posterior cervical surgery [5]. Other studies emphasized the need to correct focal cervical kyphosis and that correcting a patient's driver of deformity (ie, not correcting cervical/thoracic driver of deformity) can correlate with better outcomes [6,7]. In order to create a patient specific set of parameters for surgeons to aim for when correcting CD we first worked to classify patient's based on overall cervical and global spinal alignment.

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    Conflict of interest statement: The International Spine Study Group (ISSG) is funded through research grants from DePuy Spine and individual donations. P.G.P. reports consultancy from Medicrea and Spinewave; Speaking/Teaching arrangements from Zimmer Biomet; grant from CSRS; scientific advisory board membership at Biologic Tissue Bank. A.D. reports consultancy from Stryker, DePuy Synthes, Globus, and Stryker; research/fellowship support from Orthofix. H.J.K. reports grants from DePuy Synthes and CSRS; consultancy from K2M, and Zimmer Biomet; board membership for HSS Journal, Asian Spine Journal, and Global Spine Journal. J.S.S. reports grants from DePuy Synrhes; consultancy from Zimmer Biomet, NuVasive, and Cerapedics; royalties from Zimmer Biomet; speaking/teaching arrangements from Zimmer Biomet and NuVasive. C.S. reports grants from DePuy Synthes, NIH, the Department of Defense, and AOSpine; Consultancy from Medtronic, NuVasive, Zimmer Biomet, K2M, Stryker, and In Vivo; royalties/patents from Medtronic, NuVasive, and Zimmer Biomet; stockholder earnings from NuVasive. V.L. reports grants from SRS, DePuy, K2M, Stryker, NuVasive; speaking/traching arrangements from DePuy, MSD, and AOSpine; consultancy from NuVasive; shareholder/board of directors for Nemaris Inc. T.P. reports grants from DePuy; consultancy from Medicrea, Globus, and Innovasis; research support from Zimmer Spine. C.A. reports grants from DePuy, consultancy from DePuy, Medtronic, Stryker; royalties from Stryker and Zimmer Biomet. R.H. reports grant from Medtronic; speaking fees from Globus, Seaspine, and DePuy; other disclosures from CSRS, ISSG, and ISSLS. G.M. reports consultancy from K2M, DePuy Synthes; royalties from K2M, and non-financial support from NuVasive. R.E., D.S., D.K.H., D.N., S.H., C.B., G.P., F.S., C.J., and Mr. Lafage have no conflicts of interest to report.

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