title: Cervical Sagittal Imbalance is a Predictor of Kyphotic Deformity After Laminoplasty in Cervical Spondylotic Myelopathy Patients Without Preoperative Kyphotic Alignment.
abstract: METHODS
  A retrospective cohort study.
  
  
  OBJECTIVE
  The aim of this study is to investigate the preoperative factors for postlaminoplasty kyphotic deformity in cervical spondylotic myelopathy (CSM) patients without preoperative kyphotic alignment focused on the cervical sagittal balance.
  
  
  BACKGROUND
  After laminoplasty (LAMP), appropriate decompression may be obtained when cervical lordosis is maintained to allow the posterior shift of the spinal cord. Therefore, LAMP is not suitable for patients with preoperative cervical kyphosis. However, we sometimes encounter patients who developed postoperative kyphosis despite normal preoperative alignment. The risk factors of postlaminoplasty kyphotic deformity for the patients without preoperative kyphotic alignment are not well known.
  
  
  METHODS
  A total of 174 consecutive patients who received a double-door LAMP for CSM without preoperative kyphotic alignment and completed a 1-year follow-up were enrolled. Cervical lateral X-ray images obtained in the standing position were measured at the preoperative stage and during a 1-year follow-up visit. The radiographic measurements included the following: (1) C2-7 lordotic angle (C2-7 angle), (2) C2-7 range of motion (C2-7 ROM), (3) CGH (center of gravity of the head)-C7 SVA, and (4) C7 slope. The clinical results were evaluated using the Japanese Orthopedic Association score system for cervical myelopathy (C-JOA score).
  
  
  RESULTS
  Postoperative kyphotic deformity was observed in 9 patients (5.2%). The recovery rates of the C-JOA scores at the 1-year follow-up period in the kyphotic deformity (+) group were inferior to those of the kyphotic deformity (-) group. The CGH-C7 SVA and advanced age were detected as preoperative risk factors using multivariate analysis. Cutoff values for predicting postlaminoplasty kyphotic deformity were a CGH-C7 SVA = 42 mm and an age of 75 years.
  
  
  CONCLUSIONS
  Cervical sagittal imbalance and advanced age were the preoperative risk factors for kyphotic deformity after LAMP for CSM in patients without preoperative cervical kyphotic alignment.
  
  
  METHODS
  4.
authors.affiliation: *Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, Saitama†Department of Orthopedic Surgery, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Sakai
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Yoshii
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirai
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Arai
authors.forename: Ichiro
authors.initials: I
authors.lastname: Torigoe
authors.forename: Masaki
authors.initials: M
authors.lastname: Tomori
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Sato
authors.forename: Atsushi
authors.initials: A
authors.lastname: Okawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000453:epidemiology* / Q000209:etiology; D065406:Laminoplasty / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D055009:Spondylosis / Q000601:surgery*