title: Clinical and radiological results of total disc replacement in the cervical spine with preoperative reducible kyphosis.
abstract: OBJECTIVE
  To investigate the clinical and radiological results of total disc replacement (TDR) in the cervical spine with preoperative reducible kyphosis, and discuss when TDR is indicated for the patients with preoperative kyphosis.
  
  
  METHODS
  Fifty-two patients who underwent single-level cervical TDR from June 2008 to May 2010 were included in this study. TDR was indicated for patients with preoperative lordosis or reducible kyphosis, and the patients were divided into a lordotic group (preoperative global angle of ≥0°) and kyphotic group (preoperative global angle of <0°). Clinical results were evaluated using the Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS) score and Neck Disablity Index (NDI). For radiological evaluation, the global and functional spinal unit (FSU) angles and the global and FSU range of motion were measured preoperatively and postoperatively.
  
  
  RESULTS
  The mean NDI in the kyphotic group was significantly higher than that in the lordotic group preoperatively and at six months postoperatively, but the groups showed no significant differences in JOA score, VAS score and NDI at the two year follow-up. The mean global and FSU angles in the kyphotic group were significantly lower than those in the lordotic group preoperatively and at six months postoperatively, but they gradually improved postoperatively. The differences lost significance at the two year follow-up.
  
  
  CONCLUSIONS
  Postoperative cervical kyphosis had adverse effects on the NDI after TDR. Artificial discs, symptom relief, and neck functional exercises may contribute to correction of preoperative reducible kyphosis at different stages after cervical TDR. Preoperative reducible kyphosis should not be an independent contraindication for cervical TDR.
authors.affiliation: Orthopedic Research Institute of the Chinese People's Liberation Army, Department of Orthopedic Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Zhimin
authors.initials: Z
authors.lastname: He
authors.forename: Haisong
authors.initials: H
authors.lastname: Yang
authors.forename: Xinwei
authors.initials: X
authors.lastname: Wang
authors.forename: Deyu
authors.initials: D
authors.lastname: Chen
mesh_terms: D000328:Adult; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D059145:Total Disc Replacement