title: Endplate changes following discectomy: natural history and associations between imaging and clinical data.
abstract: OBJECTIVE
  Some patients will experience post-operative back pain following lumbar discectomy, and the potential sources for that pain are poorly understood. One potential source is the vertebral endplates. The goal of this study was to document the changes that occur in lumbar endplates following discectomies, and to assess associations between endplate changes and clinical outcomes.
  
  
  METHODS
  Changes in lumbar endplates and discs were assessed from X-rays, CT and MRI exams by comparing preoperative imaging with imaging obtained at yearly intervals up to 5 years. 260 endplates in 137 patients with single-level herniation and discectomy were analyzed. The geometry of osseous defects in the endplates was measured from the CT exams, and marrow and disc changes adjacent to endplates were assessed from the MRI exams. Clinical outcome assessments were collected at each time point. Descriptive statistics were used to describe endplate defect sizes, and logistic regression and analysis of variance were used to identify potential associations between endplate and vertebral body changes and clinical outcomes.
  
  
  RESULTS
  Approximately 14 % of the endplates had osseous defects prior to surgery. After surgery, 24 % of inferior and 43 % of superior endplates had defects. Change occurred within the first year and remained relatively constant over the next few years. Disc signal intensity worsened and disc height decreased following surgery. New Modic changes were also observed. None of these changes were associated with having achieved a clinically significant improvement in outcome scores. The follow-up rates were low at the later time points and significant associations cannot be ruled out.
  
  
  CONCLUSIONS
  This study documents lesion characteristics in detail and supports that osseous defects in the endplates at the level of a lumbar discectomy may be a relatively common finding following surgery, along with disc height loss, loss of disc signal intensity, and Modic changes. The clinical significance of these imaging findings could not be conclusively determined in this study.
authors.affiliation: Department of Orthopaedic Surgery, The Methodist Hospital, Houston, TX, USA.
authors.forename: Bradley K
authors.initials: BK
authors.lastname: Weiner
authors.affiliation: Klinicka Bolnica Dubrava, Zagreb, Croatia.
authors.forename: Milorad
authors.initials: M
authors.lastname: Vilendecic
authors.affiliation: KBC Rijeka, Rijeka, Croatia.
authors.forename: Darko
authors.initials: D
authors.lastname: Ledic
authors.affiliation: University Clinic for Neurosurgery, University Hospital and Medical University, Graz, Austria.
authors.forename: Sandro
authors.initials: S
authors.lastname: Eustacchio
authors.affiliation: National Center for Spinal Disorders, Budapest, Hungary.
authors.forename: Peter
authors.initials: P
authors.lastname: Varga
authors.affiliation: Orthopedic Clinic Ljubljana, Ljubljana, Slovenia.
authors.forename: Miro
authors.initials: M
authors.lastname: Gorensek
authors.affiliation: Department of Orthopaedic Surgery, The Methodist Hospital, Houston, TX, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Fernandez-Moure
authors.affiliation: Medical Metrics, Research, 2121 Sage Rd, Suite 300, Houston, TX, 77056, USA. drhipp@earthlink.net.
authors.forename: John A
authors.initials: JA
authors.lastname: Hipp
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001853:Bone Marrow / Q000473:pathology; D017586:Diskectomy / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D016015:Logistic Models; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008161:Lumbosacral Region / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000209:etiology* / Q000473:pathology; D014057:Tomography, X-Ray Computed
keywords: Clinical outcomes; Endplate changes; Imaging; Lumbar discectomy