title: Three-dimensional kinematic analysis of the cervical spine after anterior cervical decompression and fusion at an adjacent level: a preliminary report.
abstract: OBJECTIVE
  Development of adjacent segment degeneration following anterior cervical decompression and fusion (ACDF) is still controversial, as adjacent-level kinematics is poorly understood. This study reports preliminary data from a high-accuracy 3D analysis technique developed for in vivo cervical kinematics.
  
  
  METHODS
  From nine cervical spondylosis patients, four underwent single-level ACDF, and five underwent two-level ACDF using cylindrical titanium cage implant(s). Pre- and post-surgical CT scans were taken in flexion, neutral and extended positions, allowing us to compute segmental ranges of motion for rotation and translation, and 3D disc-height distributions. Differences in segmental motions and disc-height between fused and adjacent levels were analyzed with a Wilcoxon signed-rank test. Results are presented as mean ± SEM.
  
  
  RESULTS
  The flexion/extension angular-ROM at the fusion level decreased after surgery (7.46 ± 1.17° vs. 3.14 ± 0.56°, p < 0.003). The flexion/extension angular-ROM at one caudal adjacent level to the fusion level (3.97 ± 1.29°) tended to be greater post-operatively (6.11 ± 1.44°, p = 0.074). Translation in the anterior-posterior direction during flexion/extension at the fusion level decreased after surgery (1.22 ± 0.20 mm vs. 0.32 ± 0.11 mm, p < 0.01). No differences were found in adjacent-level disc heights between both study time-points.
  
  
  CONCLUSIONS
  This study showed increased segmental motion in flexion/extension angular-ROM at one level adjacent to ACDF. However, increases in the rotational angular-ROM were not statistically significant when cranial/caudal adjacent levels were analyzed separately. This preliminary study highlighted the capabilities of a 3D-kinematic analysis method to detect subtle changes in kinematics and disc height at the adjacent levels to ACDF. Thus, reliable evidence related to ACDF's influence on adjacent-level cervical kinematics can be collected.
authors: Center for Spine and Spinal Cord Disorders, Southern Tohoku General Hospital, 1-2-5 Satonomori, Iwanuma, Miyagi 989-2483, Japan.
authors: Sadayoshi
authors: S
authors: Watanabe
authors: Nozomu
authors: N
authors: Inoue
authors: Tomonori
authors: T
authors: Yamaguchi
authors: Yoshitaka
authors: Y
authors: Hirano
authors: Alejandro A
authors: AA
authors: Espinoza Orías
authors: Shintaro
authors: S
authors: Nishida
authors: Yuichi
authors: Y
authors: Hirose
authors: Junichi
authors: J
authors: Mizuno
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D019299:Decompression, Surgical / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*; D055009:Spondylosis / Q000503:physiopathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods*