title: Traumatic fracture-dislocation of C5 on C6 through a previously solid multilevel anterior cervical discectomy and fusion: a case report and review of the literature.
abstract: BACKGROUND
  Due to the underlying pathology and altered biomechanics, traumatic cervical fractures have been reported in patients with ankylosing spondylitis (AS), diffuse idiopathic skeletal hyperostosis (DISH), ossification of the posterior longitudinal ligament (OPLL), and combination of DISH and OPLL. However, incidence of a fracture-dislocation through a solid multilevel anterior cervical discectomy and fusion (ACDF) construct with no associated underlying pathology of AS, DISH, or OPLL but severe osteopenia has not, to the best knowledge of the authors, been reported in the medical literature.
  
  
  OBJECTIVE
  To report the development of an unstable cervical spine fracture that occurred through a previous multilevel anterior cervical fusion and the challenges associated with the diagnosis and surgical management of these uncommon lesions.
  
  
  METHODS
  A case report and review of the literature.
  
  
  METHODS
  A case report entailing the clinical history, operative management, and postoperative course of a 72-year-old male patient with no known AS, DISH, or OPLL who suffered a cervical spine fracture-dislocation, secondary to a motor vehicle accident, through a previous solid three-level ACDF that was performed 20 years earlier.
  
  
  RESULTS
  The patient underwent emergent reduction and realignment of the cervical fracture-dislocation, eventual posterior spinal fusion and stabilization with rigid segmental internal fixation, and application of external halo immobilization. At recent follow-up, he has radiographic evidence of fusion and maintenance of sagittal alignment without loss of reduction.
  
  
  CONCLUSIONS
  Multilevel cervical fusion constructs are susceptible to traumatic injuries. Many of the same challenges in the management of the previously fused ACDF patient, who sustains a fracture-dislocation, are similar to those found in the patient with mass-inflammatory conditions or metabolic disorders, such as AS, DISH, or OPLL. In many cases, this includes severe osteopenia, long unstable fusion segments, and difficulties associated with prolonged halo vest immobilization. As a result, preoperative surgical planning should take into consideration the difficulties in achieving fracture reduction, decompression, and proper stabilization.
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia, P.O. Box 800159, Charlottesville, VA 22908, USA.
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Orndorff
authors.forename: Dino
authors.initials: D
authors.lastname: Samartzis
authors.forename: Richard
authors.initials: R
authors.lastname: Whitehill
authors.forename: Francis H
authors.initials: FH
authors.lastname: Shen
mesh_terms: D000063:Accidents, Traffic; D000368:Aged; D002574:Cervical Vertebrae; D017586:Diskectomy / Q000009:adverse effects / Q000379:methods*; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D020127:Recovery of Function; D018570:Risk Assessment; D013119:Spinal Cord Injuries / Q000000981:diagnostic imaging / Q000601:surgery; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*; D016896:Treatment Outcome