Cervical mismatch: the normative value of T1 slope minus cervical lordosis and its ability to predict ideal cervical lordosis

International Spine Study Group

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

OBJECTIVENumerous studies have attempted to delineate the normative value for T1S-CL (T1 slope minus cervical lordosis) as a marker for both cervical deformity and a goal for correction similar to how PI-LL (pelvic incidence-lumbar lordosis) mismatch informs decision making in thoracolumbar adult spinal deformity (ASD). The goal of this study was to define the relationship between T1 slope (T1S) and cervical lordosis (CL).METHODSThis is a retrospective review of a prospective database. Surgical ASD cases were initially analyzed. Analysis across the sagittal parameters was performed. Linear regression analysis based on T1S was used to provide a clinically applicable equation to predict CL. Findings were validated using the postoperative alignment of the ASD patients. Further validation was then performed using a second, normative database. The range of normal alignment associated with horizontal gaze was derived from a multilinear regression on data from asymptomatic patients.RESULTSA total of 103 patients (mean age 54.7 years) were included. Analysis revealed a strong correlation between T1S and C0-7 lordosis (r = 0.886), C2-7 lordosis (r = 0.815), and C0-2 lordosis (r = 0.732). There was no significant correlation between T1S and T1S-CL. Linear regression analysis revealed that T1S-CL assumed a constant value of 16.5° (R2 = 0.664, standard error 2°). These findings were validated on the postoperative imaging (mean absolute error [MAE] 5.9°). The equation was then applied to the normative database (MAE 6.7° controlling for McGregor slope [MGS] between -5° and 15°). A multilinear regression between C2-7, T1S, and MGS demonstrated a range of T1S-CL between 14.5° and 26.5° was necessary to maintain horizontal gaze.CONCLUSIONSNormative CL can be predicted via the formula CL = T1S - 16.5° ± 2°. This implies a threshold of deformity and aids in providing a goal for surgical correction. Just as pelvic incidence (PI) can be used to determine the ideal LL, T1S can be used to predict ideal CL. This formula also implies that a kyphotic cervical alignment is to be expected for individuals with a T1S < 16.5°.

Original languageEnglish (US)
Pages (from-to)31-37
Number of pages7
JournalJournal of neurosurgery. Spine
Volume30
Issue number1
DOIs
StatePublished - Oct 5 2018

Keywords

  • ASD = adult spinal deformity
  • C0 = occiput
  • CBVA = chin-brow vertical angle
  • cervical lordosis
  • cervical mismatch
  • CL = cervical lordosis (C2–7 lordosis)
  • cSVA = cervical SVA
  • deformity
  • HRQOL = health-related quality of life
  • LL = lumbar lordosis
  • MAE = mean absolute error
  • MGS = McGregor slope
  • PI = pelvic incidence
  • PT = pelvic tilt
  • RMSE = root mean square error
  • sagittal alignment
  • SVA = sagittal vertical axis
  • T1 slope
  • T1S = T1 slope
  • T1S−CL
  • T1S−CL = T1S minus CL
  • TIA = thoracic inlet angle
  • TK = thoracic kyphosis

ASJC Scopus subject areas

  • Surgery
  • Neurology
  • Clinical Neurology

Fingerprint Dive into the research topics of 'Cervical mismatch: the normative value of T1 slope minus cervical lordosis and its ability to predict ideal cervical lordosis'. Together they form a unique fingerprint.

  • Cite this