title: Plate-only open door laminoplasty maintains stable spinal canal expansion with high rates of hinge union and no plate failures.
abstract: METHODS
  Prospective clinical series.
  
  
  OBJECTIVE
  To evaluate the ability of plate-only laminoplasty to achieve stable laminar arch reconstruction and to determine the rate and time course with which bony healing occurs in such constructs.
  
  
  BACKGROUND
  Reconstruction of a stable laminar arch with sufficient room for the decompressed spinal cord is a desired goal when performing cervical laminoplasty for myelopathy. Traditional forms of laminoplasty fixation, such as sutures, bone struts, and ceramic spacers, may be associated with complications including loss of fixation, dislodgement with neurologic compromise, and premature laminoplasty closure. Plates, in contrast, provide more rigid fixation. Plate-only laminoplasty is gaining popularity as a method of laminoplasty fixation, but there is little data on its effectiveness.
  
  
  METHODS
  Fifty-four patients who underwent open door laminoplasty for cervical myelopathy and had available postoperative computed tomography (CT) scans formed the basis of this study. In all cases, a 4-mm round burr was used to create the hinge at the junction of the lateral mass and lamina by completely removing the dorsal cortex and thinning the ventral cortex until a greenstick deformation of the hinge could be produced. Laminoplasty plates were used as the sole method of fixation. No supplemental bone graft struts were used on the plated side, and the hinge side was not bone grafted. Axial CT scans obtained at 3, 6, and 12 months postoperatively were assessed for plate complications and bony healing of the hinge.
  
  
  RESULTS
  No plate failures, dislodgements, or premature closures occurred in any of the levels at any time postoperatively. Computed tomography scan review demonstrated that 55% of levels were healed at 3 months, 77% at 6 months, and 93% at 12 months. At each timepoint, C6 and C7 had the highest hinge healing rates. Laminar screw backout was seen in 5/217 (2.3%) of levels, but was not associated with plate dislodgement, laminoplasty closure, or neurologic consequences, and did not occur in any case in which 2 laminar screws had been placed.
  
  
  CONCLUSIONS
  Plate-only laminoplasty provided stable reconstruction of an expanded laminar arch with no failures, dislodgements, adverse neurologic consequences, or premature closures in 217 levels. Ninety-three percent of hinges demonstrated radiographic union at 12 months, and even those that did not heal by CT scan criteria maintained patent expansion of the spinal canal without adverse neurologic consequences. Supplemental bone graft does not appear necessary when plated laminoplasty is performed.
authors.affiliation: Emory Spine Center, Department of Orthopaedic Surgery, Emory University School of Medicine, Atlanta, Georgia, USA. john.rhee@emory.org
authors.forename: John M
authors.initials: JM
authors.lastname: Rhee
authors.forename: Bradley
authors.initials: B
authors.lastname: Register
authors.forename: Takahiko
authors.initials: T
authors.lastname: Hamasaki
authors.forename: Betty
authors.initials: B
authors.lastname: Franklin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001860:Bone Plates; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D016009:Chi-Square Distribution; D019299:Decompression, Surgical / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D019637:Orthopedic Procedures / Q000009:adverse effects / Q000295:instrumentation*; D016348:Osseointegration; D011446:Prospective Studies; D015203:Reproducibility of Results; D013117:Spinal Cord Compression / Q000601:surgery*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome