title: Screw Back-Out Following "Open-Door" Cervical Laminoplasty: A Review of 165 Plates.
abstract: METHODS
  Retrospective study.
  
  
  OBJECTIVE
  To investigate safety profile of open door laminoplasty plates.
  
  
  BACKGROUND
  Few reports have documented potential complications related to the use of cervical laminoplasty plates.
  
  
  METHODS
  Records and radiographs of consecutive plated laminoplasty patients of one academic surgeon were analyzed. Group 1 had screw back-out, defined as change in screw position, and group 2 did not.
  
  
  RESULTS
  Forty-two patients (mean age, 56.9) underwent "open-door" cervical laminoplasty using 165 plates. Mean follow-up was 24 months (range, 12-49 months). Mean Nurick grade improved from 2.1 to 0.9 postoperatively. Cervical lordosis (C2-7) was 12.1° preoperatively and 10.0° postoperatively. Range-of-motion was 27.0° preoperatively and 23.4° postoperatively. Partial screw back-out was noted in 27 of 165 plates (16.4%) and in 34 of 660 screws (5.2%). Of the 34 screws, 27 (79.4%) were at either the most cranial (12/27, 44.4%) or the most caudal (15/27, 55.5%) level. Cranially, 11/12 screws (91.7%) had back-out. Caudally, 9/15 lateral mass screws (60.0%) backed-out versus 6 laminar screws (40.0%). Of the 22 patients with screw back-out, 15 (68.2%) occurred <3 months postoperative and 6 (27.3%) occurred 4-12 months postoperative. No statistical differences were found between group 1 and 2 for age, gender, preoperative and postoperative lordosis, focal sagittal alignment, range-of-motion, or Nurick grade. Despite screw backout in 22 patients, there were no plate dislodgements, laminoplasty closure, or neurological deterioration.
  
  
  CONCLUSIONS
  Although screw back-out may occur with the use of cervical laminoplasty plates, the use of these plates without a bone block appears to be safe and reliable. As screw back-out is most common at the cranial and caudal ends of the laminoplasty, we recommend using the maximum number of screws (typically 2 for the lateral mass and 2 for the spinous process) at these levels to secure the plate to the bone.
authors.affiliation: Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore and University Spine Centre, University Orthopaedics, Hand and Reconstructive Microsurgery Cluster, National University Hospital, Singapore.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Orthopaedic Surgery, University, St. Louis, MO, USA.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Buchowski
authors.affiliation: Department of Orthopaedic Surgery, Columbia University Medical Center, New York, NY, USA.
authors.forename: K Daniel
authors.initials: KD
authors.lastname: Riew
keywords: Cervical myelopathy; Laminoplasty; Loosening; Plates; Screw