TY - JOUR
T1 - The morphology of cervical deformities
T2 - A two-step cluster analysis to identify cervical deformity patterns
AU - and the International Spine Study Group
AU - Kim, Han Jo
AU - Virk, Sohrab
AU - Elysee, Jonathan
AU - Passias, Peter
AU - Ames, Christopher
AU - Shaffrey, Christopher I.
AU - Mundis, Gregory
AU - Protopsaltis, Themistocles
AU - Gupta, Munish
AU - Klineberg, Eric
AU - Smith, Justin S.
AU - Burton, Douglas
AU - Schwab, Frank
AU - Lafage, Virginie
AU - Lafage, Renaud
N1 - Funding Information:
AlloSource, the Cervical Scoliosis Research Society, Globus Medical, Medicrea, SpineWave, and Zimmer Biomet. Dr. Ames reports he is an employee of the University of California, San Francisco; he is a consultant for DePuy Synthes, Medtronic, Stryker, Medicrea, K2M, and Zimmer Biomet; he receives royalties from Stryker, Zimmer Biomet, DePuy Synthes, NuVasive, Next Orthosurgical, K2M, and Medicrea; he does research for Titan Spine, DePuy Synthes, and the International Spine Study Group (ISSG); he is on the editorial board of Operative Neurosurgery; he has received grant funding from the Scoliosis Research Society; he is on the executive committee of ISSG; and he is the director of Global Spine Analytics. Dr. Shaffrey reports he owns stock in NuVasive; he is a consultant for Medtronic, NuVasive, SI-Bone, and Siemens; and he holds patents with Medtronic, NuVasive, Zimmer Biomet, and SI-Bone. Dr. Mundis reports being a consultant for NuVasive, K2M, Viseon, and SeaSpine; and he owns stock in NuVasive and Viseon. Dr. Gutpa reports being a consultant for Medtronic and DePuy Synthes; he owns stock in J&J and P&G; he receives royalties from Innomed; he has received funds for travel expenses from Medicrea; and his institution receives grant funding for a fellowship from AOSpine and OMeGA. Dr. Klineberg reports being a consultant for DePuy Synthes, Stryker, and Medicrea; and he has received fellowship grant funding and honoraria from AOSpine. Dr. Smith reports being a consultant for Zimmer Biomet, NuVasive, Stryker, AlloSource, and Cerapedics; he received clinical or research support for the present study from DePuy Synthes and ISSG, which also provided funding for non–study-related clinical or research efforts that he oversees; he has received fellowship support from NREF and AOSpine; he receives royalties from Zimmer Biomet and NuVasive; and he owns stock in Alphatec. Dr. Burton reports receiving clinical or research support for the present study from DePuy Synthes; he is a consultant for Bioventus; he has received funding of non–study-related clinical or research efforts that he oversees from Pfizer; and he holds a patent with DePuy Synthes. Dr. Schwab reports being a consultant for Globus Medical, Zimmer Biomet, K2M, and MSD; he has received funding for non–study-related clinical or research efforts that he oversees from DePuy Synthes, K2M, NuVasive, Medtronic, AlloSource, Orthofix, and SI-Bone through ISSG; and he has paid speaking/ teaching arrangements with Globus Medical, Zimmer Biomet, K2M, and MSD. Dr. V. LaFage reports she has received funding for non–study-related clinical or research efforts that she oversees from DePuy Synthes, K2M, NuVasive, Medtronic, AlloSource, Orthofix, and SI-Bone through ISSG; she is a consultant for Globus Medical; and she has paid teaching/speaking arrangements with DePuy Synthes. Mr. R. LaFage reports owning stock in Nemaris.
Funding Information:
The International Spine Study Group is funded through research grants from DePuy Synthes (current), NuVasive (current), K2M (current), Innovasis (past), Biomet (past), and individual
Publisher Copyright:
©AANS 2020, except where prohibited by US copyright law
PY - 2020
Y1 - 2020
N2 - OBJECTIVE Cervical deformity (CD) is difficult to define due to the high variability in normal cervical alignment based on postural- and thoracolumbar-driven changes to cervical alignment. The purpose of this study was to identify whether patterns of sagittal deformity could be established based on neutral and dynamic alignment, as shown on radiographs. METHODS This study is a retrospective review of a prospective, multicenter database of CD patients who underwent surgery from 2013 to 2015. Their radiographs were reviewed by 12 individuals using a consensus-based method to identify severe sagittal CD. Radiographic parameters correlating with health-related quality of life were introduced in a two-step cluster analysis (a combination of hierarchical cluster and k-means cluster) to identify patterns of sagittal deformity. A comparison of lateral and lateral extension radiographs between clusters was performed using an ANOVA in a post hoc analysis. RESULTS Overall, 75 patients were identified as having severe CD due to sagittal malalignment, and they formed the basis of this study. Their mean age was 64 years, their body mass index was 29 kg/m2, and 66% were female. There were significant correlations between focal alignment/flexibility of maximum kyphosis, cervical lordosis, and thoracic slope minus cervical lordosis (TS-CL) flexibility (r = 0.27, 0.31, and -0.36, respectively). Cluster analysis revealed 3 distinct groups based on alignment and flexibility. Group 1 (a pattern involving a flat neck with lack of compensation) had a large TS-CL mismatch despite flexibility in cervical lordosis; group 2 (a pattern involving focal deformity) had focal kyphosis between 2 adjacent levels but no large regional cervical kyphosis under the setting of a low T1 slope (T1S); and group 3 (a pattern involving a cervicothoracic deformity) had a very large T1S with a compensatory hyperlordosis of the cervical spine. CONCLUSIONS Three distinct patterns of CD were identified in this cohort: flat neck, focal deformity, and cervicothoracic deformity. One key element to understanding the difference between these groups was the alignment seen on extension radiographs. This information is a first step in developing a classification system that can guide the surgical treatment for CD and the choice of fusion level.
AB - OBJECTIVE Cervical deformity (CD) is difficult to define due to the high variability in normal cervical alignment based on postural- and thoracolumbar-driven changes to cervical alignment. The purpose of this study was to identify whether patterns of sagittal deformity could be established based on neutral and dynamic alignment, as shown on radiographs. METHODS This study is a retrospective review of a prospective, multicenter database of CD patients who underwent surgery from 2013 to 2015. Their radiographs were reviewed by 12 individuals using a consensus-based method to identify severe sagittal CD. Radiographic parameters correlating with health-related quality of life were introduced in a two-step cluster analysis (a combination of hierarchical cluster and k-means cluster) to identify patterns of sagittal deformity. A comparison of lateral and lateral extension radiographs between clusters was performed using an ANOVA in a post hoc analysis. RESULTS Overall, 75 patients were identified as having severe CD due to sagittal malalignment, and they formed the basis of this study. Their mean age was 64 years, their body mass index was 29 kg/m2, and 66% were female. There were significant correlations between focal alignment/flexibility of maximum kyphosis, cervical lordosis, and thoracic slope minus cervical lordosis (TS-CL) flexibility (r = 0.27, 0.31, and -0.36, respectively). Cluster analysis revealed 3 distinct groups based on alignment and flexibility. Group 1 (a pattern involving a flat neck with lack of compensation) had a large TS-CL mismatch despite flexibility in cervical lordosis; group 2 (a pattern involving focal deformity) had focal kyphosis between 2 adjacent levels but no large regional cervical kyphosis under the setting of a low T1 slope (T1S); and group 3 (a pattern involving a cervicothoracic deformity) had a very large T1S with a compensatory hyperlordosis of the cervical spine. CONCLUSIONS Three distinct patterns of CD were identified in this cohort: flat neck, focal deformity, and cervicothoracic deformity. One key element to understanding the difference between these groups was the alignment seen on extension radiographs. This information is a first step in developing a classification system that can guide the surgical treatment for CD and the choice of fusion level.
KW - Cervical deformity
KW - Cervicothoracic deformity
KW - Cluster analysis
KW - Extension alignment
KW - Flat neck
KW - Focal deformity
UR - http://www.scopus.com/inward/record.url?scp=85080937637&partnerID=8YFLogxK
U2 - 10.3171/2019.9.SPINE19730
DO - 10.3171/2019.9.SPINE19730
M3 - Article
C2 - 31731275
AN - SCOPUS:85080937637
SN - 1547-5654
VL - 32
SP - 353
EP - 359
JO - Journal of Neurosurgery: Spine
JF - Journal of Neurosurgery: Spine
IS - 3
ER -