title: Radiological Determination of Postoperative Cervical Fusion: A Systematic Review.
abstract: METHODS
  Systematic review.
  
  
  OBJECTIVE
  To determine best criteria for radiological determination of postoperative subaxial cervical fusion to be applied to current clinical practice and ongoing future research assessing fusion to standardize assessment and improve comparability.
  
  
  BACKGROUND
  Despite availability of multiple imaging modalities and criteria, there remains no method of determining cervical fusion with absolute certainty, nor clear consensus on specific criteria to be applied.
  
  
  METHODS
  A systematic search in MEDLINE/Cochrane Collaboration Library (through March 2014). Included studies assessed C2 to C7 via anterior or posterior approach, at 12 weeks or more postoperative, with any graft or implant. Overall body of evidence with respect to 6 posited key questions was determined using Grading of Recommendations Assessment, Development and Evaluation and Agency for Healthcare Research and Quality precepts.
  
  
  RESULTS
  Of plain radiographical modalities, there is moderate evidence that the interspinous process motion method (<1 mm) is more accurate than the Cobb angle method for assessing anterior cervical fusion. Of the advanced imaging modalities, there is moderate evidence that computed tomography (CT) is more accurate and reliable than magnetic resonance imaging in assessing anterior cervical fusion. There is insufficient evidence regarding the optimal modality and criteria for assessing posterior cervical fusions and insufficient evidence to support a single time point after surgery as being optimal for determining fusion, although some evidence suggest that reliability of radiography and CT improves with increasing time postoperatively.
  
  
  CONCLUSIONS
  We recommend using less than 1-mm motion as the initial modality for determining anterior cervical arthrodesis for both clinical and research applications. If further imaging is needed because of indeterminate radiographical evaluation, we recommend CT, which has relatively high accuracy and reliability, but due to greater radiation exposure and cost, it is not routinely suggested. We recommend that plain radiographs also be the initial method of determining posterior cervical fusion but suggest a lower threshold for obtaining CT scans because dynamic radiographs may not be as useful if spinous processes have been removed by laminectomy.
  
  
  METHODS
  1.
authors.affiliation: *Department of Orthopaedic Surgery, Emory Spine Center, Emory University, Atlanta, GA †Department of Orthopedics and Sports Medicine, University of Washington, Seattle, WA ‡Spectrum Research, Inc., Tacoma, WA §University of Virginia, Charlottesville, VA; and ¶Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO.
authors.forename: John M
authors.initials: JM
authors.lastname: Rhee
authors.forename: Jens R
authors.initials: JR
authors.lastname: Chapman
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Norvell
authors.forename: Justin
authors.initials: J
authors.lastname: Smith
authors.forename: Ned A
authors.initials: NA
authors.lastname: Sherry
authors.forename: K Daniel
authors.initials: KD
authors.lastname: Riew
mesh_terms: D001696:Biomechanical Phenomena; D016025:Bone Transplantation; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D003697:Delphi Technique; D019317:Evidence-Based Medicine; D006801:Humans; D007796:Laminectomy; D008279:Magnetic Resonance Imaging; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D020127:Recovery of Function; D015203:Reproducibility of Results; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome