title: Analysis of cervical kyphosis and spinal balance in young idiopathic scoliosis patients classified by the apex of thoracic kyphosis.
abstract: Sagittal balance has recently been the focus of studies aimed at understanding the correction force required for both coronal and sagittal malalignment. However, the correlation between cervical kyphosis and sagittal balance in AIS patients has yet to be thoroughly investigated. This study aimed to clarify the correlation between cervical alignment and spinal balance in patients with adolescent idiopathic scoliosis (AIS). Here, we hypothesized that cervical kyphosis patients can be classified into groups by the apex of thoracic kyphosis.
  
  
  
  This study included 92 AIS patients (84 females, 8 males; mean age, 15.1 years). Patients were divided into the cervical lordosis (CL), cervical sigmoid (CS), or cervical kyphosis (CK) groups and further classified according to the apex of thoracic kyphosis into High (above T3), Middle (T4-T9), and Low (below T10) groups.
  
  
  
  There were 17 (18.5 %), 22 (23.9 %), and 53 (57.6 %) patients with CL, CS, and CK, respectively. In the CK group, 13 had CK-High, 35 had CK-Middle, and 5 had CK-Low. The C7 sagittal vertical axis (C7SVA) measurements were most backward in CK-High and most forward in CK-Low. The T5-12 kyphosis (TK) measurement was significantly lower in CK-High.
  
  
  
  Most AIS patients had kyphotic cervical alignment. Patients with CK can be classified as having CK-High, CK-Middle, or CK-Low according to the apex of thoracic kyphosis. CK-High is due to thoracic hypokyphosis with a backward balanced C7SVA. CK-Middle is well-balanced cervical kyphosis. CK-Low has forward-bent global kyphosis of the cervicothoracic spine that positioned the C7SVA forward.
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Kenyu
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan. imagama@med.nagoya-u.ac.jp.
authors.forename: Shiro
authors.identifier: 0000-0002-6951-8575
authors.initials: S
authors.lastname: Imagama
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Zenya
authors.initials: Z
authors.lastname: Ito
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Ando
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Hida
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Mikito
authors.initials: M
authors.lastname: Tsushima
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Yoshimoto
authors.initials: Y
authors.lastname: Ishikawa
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Akiyuki
authors.initials: A
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nishida
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University Hospital, Graduate School of Medicine, Shiro Imagama, 65 Tsurumai Showa-ward, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
mesh_terms: D000293:Adolescent; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging*; D008297:Male; D004856:Postural Balance; D012600:Scoliosis / Q000000981:diagnostic imaging*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Cervical; Classification; Kyphosis; Sagittal; Scoliosis