title: Delayed hinge fracture after plate-augmented, cervical open-door laminoplasty and its clinical significance.
abstract: BACKGROUND
  Among the various forms of laminoplasty fixation, plate augmentation provides a semirigid arch reconstruction and is gaining popularity as the result of its safety and effectiveness. However, the effects of this procedure on hinge status and subsequent bony healing remain unclear.
  
  
  OBJECTIVE
  We sought to evaluate the status and time course of bony healing of the hinge gutter and to determine the effect on postoperative clinical course of plate-only, open-door cervical laminoplasty.
  
  
  METHODS
  This was a retrospective clinical series.
  
  
  METHODS
  A total of 79 adult men and women undergoing cervical laminoplasty in a university hospital setting were studied.
  
  
  METHODS
  Time-dependent changes in hinges observed on computed tomography (CT) were used to measure the radiological outcome. A numerical rating scale of axial neck pain and arm pain was used to evaluate the clinical outcome.
  
  
  METHODS
  Patients who underwent plate-only, open-door laminoplasty for cervical myelopathy and had available postoperative CT scans were enrolled in this study. Neck pain intensity before and 1 year after surgery was assessed with questionnaires. CT scans (n=125) obtained after surgery were assessed in terms of bony healing of the hinge.
  
  
  RESULTS
  Most of the hinges were initially well-bent. Only 9% were found to be "fractured" or "in danger of fracture" at 1 week. Primary healing without callus formation, which is the next step of bony healing of well-bent hinges, was observed in 62% of cases at month 4. The remaining 38% were classified as "fractured" or in the process of "secondary healing." A similar number of hinges was classified as "secondarily healed" after 1 or 2 years of follow-up. All except one hinge were well united and incorporated at the final follow-up, and the number of hinges classified as "fractured or secondarily healed" related to postoperative axial neck pain with respect to the 1-year visual analog scale for the neck and the Neck Disability Index.
  
  
  CONCLUSIONS
  Although plate-only, open-door laminoplasty is a safe and reliable surgery for decompression of multilevel cervical disease, the fixation that it provides on the open side may not be sufficiently stable to allow successful primary healing. Additional attention should be paid to the hinged side to prevent delayed fracture in the early postoperative period and to reduce postoperative axial pain.
authors.affiliation: Department of Neurosurgery, Korea University Guro Hospital, 80, Guro-dong, Guro-ku, Seoul 152-050, Republic of Korea. Electronic address: ykapa76@yahoo.co.kr.
authors.forename: Youn-Kwan
authors.initials: YK
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Korea University Guro Hospital, 80, Guro-dong, Guro-ku, Seoul 152-050, Republic of Korea.
authors.forename: Do-Yeol
authors.initials: DY
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Korea University Guro Hospital, 80, Guro-dong, Guro-ku, Seoul 152-050, Republic of Korea.
authors.forename: Junseok W
authors.initials: JW
authors.lastname: Hur
authors.affiliation: Department of Neurosurgery, Korea University Guro Hospital, 80, Guro-dong, Guro-ku, Seoul 152-050, Republic of Korea.
authors.forename: Hong-Joo
authors.initials: HJ
authors.lastname: Moon
mesh_terms: D000328:Adult; D000368:Aged; D001860:Bone Plates; D002574:Cervical Vertebrae / Q000293:injuries* / Q000601:surgery; D005260:Female; D006801:Humans; D007796:Laminectomy / Q000009:adverse effects*; D065406:Laminoplasty; D008297:Male; D008875:Middle Aged; D019547:Neck Pain / Q000209:etiology*; D010147:Pain Measurement; D011475:Prosthesis Failure; D012189:Retrospective Studies; D013118:Spinal Cord Diseases / Q000601:surgery*; D014945:Wound Healing / Q000502:physiology
keywords: Cervical laminoplasty; Hinge fracture; Plate-augmented open-door laminoplasty; Postoperative axial pain