title: Long-term magnetic resonance imaging follow-up demonstrates minimal transitional level lumbar disc degeneration after posterior spine fusion for adolescent idiopathic scoliosis.
abstract: METHODS
  Retrospective cohort study.
  
  
  OBJECTIVE
  To describe long-term clinical and imaging results focusing on the uninstrumented lumbar spine after posterior spinal fusion for adolescent idiopathic scoliosis.
  
  
  BACKGROUND
  Although previous studies found rates of low back pain after long fusion for adolescent idiopathic scoliosis which are comparable to rates found in the general population, many surgeons believe that the long lever arm associated with the fusion mass will result in increased stress at uninstrumented caudal intervertebral discs and accelerated degenerative changes.
  
  
  METHODS
  This is a retrospective chart and imaging review of adolescent idiopathic scoliosis patients treated with posterior fusion and segmental instrumentation. Patients completed follow-up examination, outcome questionnaires, radiographs, and magnetic resonance (MR) imaging. MR images were scored for evidence of degeneration of lumbar discs below the level of the fusion.
  
  
  RESULTS
  Twenty patients participated in the study, providing 90 discs below fusions for evaluation. The average follow-up was 11.8 years. The distal level of fixation was at L1 on average. The major curve averaged 55° ± 11° before surgery and was corrected to 25° ± 10° at follow-up. Follow-up MR imaging demonstrated new disc pathology in 85% of patients enrolled. Only one patient demonstrated significant degenerative disc disease at the junctional level, whereas most pathology was seen at the L5-S1 disc. The average Pfirrmann grade at uninstrumented levels deteriorated from 1.1 before surgery to 1.8 at follow-up. The greatest degree of degeneration was seen at the L5-S1 disc space where average degenerative scores increased from 1.2 before surgery to 2.3 after surgery. Three patients with severe disc disease were taking nonsteroidal anti-inflammatory drugs for pain, but no narcotics. Only mild scoliosis research society (SRS) and Oswestry changes were noted in this severe degeneration group.
  
  
  CONCLUSIONS
  Despite demonstrating an accelerated rate of L5-S1 disc degeneration, our study group has good functional scores and maintenance of correction over 10 years postfusion. In this long-term MR imaging follow-up study, disc degeneration was found remote to the lowest instrumented vertebra.
authors.affiliation: Pediatric Orthopaedic Service, Hospital for Special Surgery, New York, NY 10021, USA. greendw@hss.edu
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Green
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Lawhorne
authors.forename: Roger F
authors.initials: RF
authors.lastname: Widmann
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Kepler
authors.forename: Caitlin
authors.initials: C
authors.lastname: Ahern
authors.forename: Douglas N
authors.initials: DN
authors.lastname: Mintz
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Rawlins
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Burke
authors.forename: Oheneba
authors.initials: O
authors.lastname: Boachie-Adjei
mesh_terms: D000293:Adolescent; D000328:Adult; D005500:Follow-Up Studies; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000175:diagnosis / Q000000981:diagnostic imaging*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult