title: Dimensions of the cervical neural foramen in conditions of spinal deformity: an ex vivo biomechanical investigation using specimen-specific CT imaging.
abstract: Patients with cervical spondylosis commonly present with neck pain, radiculopathy or myelopathy. As degenerative changes progress, multiple factors including disc height loss, thoracic kyphosis, and facetogenic changes can increase the risk of neural structure compression. This study investigated the impact of cervical deformity including forward head posture (FHP) and upper thoracic kyphosis, on the anatomy of the cervical neural foramen.
  
  
  
  Postural changes of 13 human cervical spine specimens (Occiput-T1, age 50.6 years; range 21-67) were assessed in response to prescribed cervical sagittal malalignments using a previously reported experimental model. Two characteristics of cervical sagittal deformities, C2-C7 sagittal vertical alignment (SVA) and sagittal angle of the T1 vertebra (T1 tilt), were varied to create various cervical malalignments. The postural changes were documented by measuring vertebral positions and orientations. The vertebral motion data were combined with specimen-specific CT-based anatomical models, which allowed assessments of foraminal areas of subaxial cervical segments as a function of increasing C2-C7 SVA and changing T1 tilt.
  
  
  
  Increasing C2-C7 SVA from neutral posture resulted in increased neural foraminal area in the lower cervical spine (largest increase at C4-C5: 13.8 ± 15.7 %, P < 0.01). Increasing SVA from a hyperkyphotic posture (greater T1 tilt) also increased the neural foraminal area in the lower cervical segments (C5-C6 demonstrated the largest increase: 13.4 ± 9.6 %, P < 0.01). The area of the cervical neural foramen decreased with increasing T1 tilt, with greater reduction occurring in the lower cervical spine, specifically at C5-C6 (-8.6 ± 7.0 %, P < 0.01) and C6-C7 (-9.6 ± 5.6 %, P < 0.01).
  
  
  
  An increase in thoracic kyphosis (T1 tilt) decreased cervical neural foraminal areas. In contrast, an increase in cervical SVA increased the lower cervical neural foraminal areas. Patients with increased upper thoracic kyphosis may respond with increased cervical SVA as a compensatory mechanism to increase their lower cervical neural foraminal area.
authors.affiliation: Department of Neurological Surgery, Northwestern Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Smith
authors.affiliation: Musculoskeletal Biomechanics Laboratory, Edward Hines, Jr. VA Hospital, Hines, IL, 60141, USA.
authors.forename: Saeed
authors.initials: S
authors.lastname: Khayatzadeh
authors.affiliation: Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Bakhsheshian
authors.affiliation: Department of Neurological Surgery, Northwestern Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Harvey
authors.affiliation: Musculoskeletal Biomechanics Laboratory, Edward Hines, Jr. VA Hospital, Hines, IL, 60141, USA.|Department of Orthopaedic Surgery and Rehabilitation, Loyola University Medical Center, 2160 S. First Avenue, Maywood, IL, 60153, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Havey
authors.affiliation: Musculoskeletal Biomechanics Laboratory, Edward Hines, Jr. VA Hospital, Hines, IL, 60141, USA.|Department of Orthopaedic Surgery and Rehabilitation, Loyola University Medical Center, 2160 S. First Avenue, Maywood, IL, 60153, USA.
authors.forename: Leonard I
authors.initials: LI
authors.lastname: Voronov
authors.affiliation: Musculoskeletal Biomechanics Laboratory, Edward Hines, Jr. VA Hospital, Hines, IL, 60141, USA.
authors.forename: Muturi G
authors.initials: MG
authors.lastname: Muriuki
authors.affiliation: Musculoskeletal Biomechanics Laboratory, Edward Hines, Jr. VA Hospital, Hines, IL, 60141, USA. apatwar@lumc.edu.|Department of Orthopaedic Surgery and Rehabilitation, Loyola University Medical Center, 2160 S. First Avenue, Maywood, IL, 60153, USA. apatwar@lumc.edu.
authors.forename: Avinash G
authors.identifier: 0000-0003-2289-6066
authors.initials: AG
authors.lastname: Patwardhan
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006257:Head; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D009333:Neck; D011187:Posture; D012306:Risk; D055009:Spondylosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Cervical spine deformity; Forward head posture; Neck pain; Radiculopathy; Sagittal vertical alignment
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