title: Results of cervical recapping laminoplasty: gross anatomical changes, biomechanical evaluation at different time points and degrees of level involvement.
abstract: BACKGROUND
  Recapping laminoplasty has become the frequently-used approach to the spinal canal when bone decompression of the vertebral canal is not the goal. However, what changes will occur after surgery, and whether recapping laminoplasty can actually reduce the risk of delayed deformities remains unknown.
  
  
  METHODS
  We designed an animal experiment using a caprine model, and partitioned the animals into in vitro and in vivo surgical groups. We performed recapping laminoplasty on one group and laminectomy on another group. These animals were sacrificed six months after operating, cervical spines removed, biomechanically tested, and these data were compared to determine whether the recapping laminoplasty technique leads to subsequent differences in range of motion. Image data were also obtained before the surgery and when the animals were killed. Besides, we investigated the initial differences in kinetics between recapping laminoplasty and laminectomy. We did this by comparing data obtained from biomechanical testing of in vitro-performed recapping laminoplasty and laminectomy. Finally, we investigated the effect that longitudinal distance has on cervical mechanics. This was determined by performing a two-level recapping laminoplasty, and then extending the laminoplasty to the next level and repeating the mechanical testing at each step.
  
  
  RESULTS
  There were three mainly morphological changes at the six months after laminoplasty: volume reduction and bone nonunion of the recapping laminae, irregular fibrosis formation around the facet joints and re-implanted lamina-ligamentous complex. In the biomechanical test, comparing with laminectomy, recapping laminoplasty didn't show significant differences in the immediate postoperative comparison, while recapping laminoplasty demonstrated significantly decreased motion in flexion/extension six months later. Inclusion of additional levels in the laminotomy procedure didn't lead to changes in immediate biomechanics.
  
  
  CONCLUSIONS
  Recapping laminoplasty can't fully restore the posterior structure, but still reduced the risk of delayed cervical instability in a caprine model.
authors.affiliation: Department of Neurosurgery, Peking University Third Hospital, Beijing, People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Si
authors.affiliation: Department of Neurosurgery, Peking University Third Hospital, Beijing, People's Republic of China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Neurosurgery, Peking University Third Hospital, Beijing, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.affiliation: Department of Neurosurgery, Peking University Third Hospital, Beijing, People's Republic of China.
authors.forename: Guo zhong
authors.initials: Gz
authors.lastname: Lin
authors.affiliation: Department of Neurosurgery, Peking University Third Hospital, Beijing, People's Republic of China.
authors.forename: Jia
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Laboratory Animal Science, Beijing, People's Republic of China.
authors.forename: Kuo
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Clinical Epidemiology Research Center, Peking University Third Hospital, Beijing, People's Republic of China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Mechanical Engineering,Shanghai JiaoTong University, Shanghai, People's Republic of China.
authors.forename: Yuan chao
authors.initials: Yc
authors.lastname: Li
mesh_terms: D000818:Animals; D002574:Cervical Vertebrae / Q000503:physiopathology / Q000601:surgery*; D019299:Decompression, Surgical; D004195:Disease Models, Animal; D006041:Goats; D006801:Humans; D007796:Laminectomy; D065406:Laminoplasty / Q000379:methods*