title: Clinical and radiographic results of cervical artificial disc arthroplasty: over three years follow-up cohort study.
abstract: BACKGROUND
  Theoretic advantages of cervical disc arthroplasty include preservation of normal motion and biomechanics in the cervical spine, and reduction of adjacent-segment degeneration. The clinical and radiographic effects of cervical disc arthroplasty in short term have been ascertained. The aim of this study is to research the data of mid-term results.
  
  
  METHODS
  In this prospective cohort study, 50 patients who underwent cervical disc arthroplasty from December 2003 to January 2006 were enrolled. There were 39 patients who received 1-level disc arthroplasty, and 11 patients received 2-level disc arthroplasty, with an average age of 50.9 years (range from 29 to 73). The median follow-up was 41.85 months (range from 36.00 - 55.63 months). Patients were followed prospectively with respect to their symptoms, neurologic signs, and radiographic results.
  
  
  RESULTS
  The median value of Japanese Orthopaedic Association (JOA) score was 14.0 before surgery, and 16.5 at the most recent follow-up (P < 0.01). The median value of the recovery rate of the JOA score was 92.2%. The preoperative range of motion (ROM) at the indexed level was (10.40 ± 4.97)°, which has significantly correlated with the most recent follow-up ROM which was (8.56 ± 4.76)° (P < 0.05, r = 0.33). The ROM at the operative level at the most recent follow-up was greater than the value at the 3-month follow-up of (7.52 ± 3.37)° (P < 0.05). The preoperative functional spinal unit (FSU) angulation was (-0.96 ± 6.52)°, which was not significantly correlated with that of the most recent follow-up value of (-2.65 ± 7.95)° (P < 0.01, r = 0.53). The preoperative endplate angulation was (2.61 ± 4.85)°, which had no significant correlation with that of the most recent follow-up value of (0.71 ± 6.41)° (P > 0.05).
  
  
  CONCLUSIONS
  The clinical and radiographic results of cervical disc arthroplasty are good in mid-term follow-up. The normal range of motion of the operated level and the biomechanics in the cervical spine are well preserved.
authors.affiliation: Department of Spine Surgery, Beijing Jishuitan Hospital, Fourth Clinical Medical College of Peking University, Beijing 100035, China. tianweijst@vip.163.com
authors.forename: Wei
authors.initials: W
authors.lastname: Tian
authors.forename: Xiao
authors.initials: X
authors.lastname: Han
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Qin
authors.initials: Q
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Hu
authors.forename: Zhi-Yu
authors.initials: ZY
authors.lastname: Li
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yuan
authors.forename: Da
authors.initials: D
authors.lastname: He
authors.forename: Yong-Gang
authors.initials: YG
authors.lastname: Xing
mesh_terms: D000328:Adult; D000368:Aged; D019643:Arthroplasty, Replacement / Q000379:methods*; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007403:Intervertebral Disc / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome