title: Motion analysis of single-level cervical total disc arthroplasty: a meta-analysis.
abstract: OBJECTIVE
  The purpose of this review was to investigate whether cervical total disc arthroplasty (CTDA) preserves motion of the treated level and what its effect is on adjacent segments.
  
  
  METHODS
  Relevant published reports were collected from PubMed, Medline and Cochrane library. The original studies were considered eligible only if the range of motion (ROM) of the index or adjacent level had been investigated. A meta-analysis was then performed on the collected data. Statistical heterogeneity across the various trials was tested using Cochran's Q statistic and I (2) ; in the case of heterogeneity, a random effect model was used.
  
  
  RESULTS
  The weighted mean differences (WMDs) of the index level were 0.34 (95% confidence interval [CI], -0.53∼1.21, P = 0.440) and 0.23 (95% CI, -1.92∼2.38, P = 0.834) in all included studies and randomized control trials (RCTs), respectively. The WMDs of the cranial adjacent levels, caudal adjacent levels and whole cervical spines were 1.01 (95% CI, 0.55∼1.47, P = 0.000), 1.10 (95% CI, 0.61∼1.59, P = 0.000) and 3.40 (95% CI, -6.02∼12.82, P = 0.479), respectively.
  
  
  CONCLUSIONS
  These findings suggest that the protective effect against adjacent segment degeneration provided by cervical arthroplasty might not be as good as has been believed. Long-term supporting evidence is still needed.
authors.affiliation: Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Medical College of Zhejiang University and Sir Run Run Shaw Institute of Clinical Medicine of Zhejiang University, Hangzhou, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Shun-wu
authors.initials: SW
authors.lastname: Fan
authors.forename: Xin-wei
authors.initials: XW
authors.lastname: Wang
authors.forename: Wen
authors.initials: W
authors.lastname: Yuan
mesh_terms: D000328:Adult; D002574:Cervical Vertebrae / Q000502:physiology / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D013122:Spinal Diseases / Q000601:surgery*; D059145:Total Disc Replacement; D016896:Treatment Outcome