title: Impact of over distraction on occurrence of axial symptom after anterior cervical discectomy and fusion.
abstract: OBJECTIVE
  A retrospective review was undertaken to evaluate the impact of over distraction on cervical axial symptoms (AS) after anterior cervical discectomy and fusion (ACDF).
  
  
  METHODS
  The retrospective review included 421 patients who underwent ACDF for one or two segments. Of these, 78 patients for whom complete follow-up data were available were selected for inclusion in the analysis. X-rays of the cervical vertebra were performed immediately after the surgery, 3 months postsurgery, and at a final follow up (6-24 months). According to the presence/absence of AS, the patients were divided into a symptom group (Group S) and a nonsymptom group (Group N). The ratio of intervertebral height change, change in the overall cervical curvature, change in the local curvature of the surgical segment, cervical total range of motion (ROM), and Japanese Orthopaedic Association (JOA) recovery rate were compared and analyzed. A linear regression analysis of the ratio of intervertebral height change and the symptom and severity of the AS according to the Visual Analogue Scale (VAS) was carried out.
  
  
  RESULTS
  The total incidence of AS was 33.97%. C5 nerve root palsy occurred in one case in Group S after the surgery. The neurologic symptoms of both groups were significantly alleviated after the surgery. The ratio of intervertebral height change in Group S was significantly higher than that in Group N at the last follow-up (P < 0.05). However, the changes in the overall cervical curvature, local curvature of the surgical segment, cervical ROM, and JOA recovery rates were not statistically significant (P > 0.05). In Group S, 37% of the patients had symptoms that occurred in the chest area, and the ratio of intervertebral height change was significantly positively correlated with the VAS score of the AS (r = 0.893).
  
  
  CONCLUSIONS
  The occurrence of postoperative AS will significantly increase if the ratio of intervertebral height change of the surgical segment after ACDF is over 10%.
authors.affiliation: Department of Hebei Orthopaedics, The Third Hospital of Hebei Medical University139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China; Key Biomechanical Laboratory of Orthopedics139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China.
authors.forename: Jiayue
authors.initials: J
authors.lastname: Bai
authors.affiliation: Department of Hebei Orthopaedics, The Third Hospital of Hebei Medical University139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China; Key Biomechanical Laboratory of Orthopedics139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Hebei Orthopaedics, The Third Hospital of Hebei Medical University139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China; Key Biomechanical Laboratory of Orthopedics139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China.
authors.forename: Di
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Hebei Orthopaedics, The Third Hospital of Hebei Medical University139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China; Key Biomechanical Laboratory of Orthopedics139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China.
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Ding
authors.affiliation: Department of Hebei Orthopaedics, The Third Hospital of Hebei Medical University139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China; Key Biomechanical Laboratory of Orthopedics139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Department of Hebei Orthopaedics, The Third Hospital of Hebei Medical University139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China; Key Biomechanical Laboratory of Orthopedics139# Ziqiang Road, Shijiazhuang 050000, Hebei Province, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of English Teaching, Hebei Medical University 361# Zhongshan East Road, Shijiazhuang, 050000, Hebei Province, China.
authors.forename: Mengzhen
authors.initials: M
authors.lastname: Du
keywords: Cervical spondylosis; anterior cervical fusion; axial symptoms; height of intervertebral space; physiological curvature