title: Upper instrumented vertebral fractures in long lumbar fusions: what are the associated risk factors?
abstract: METHODS
  A retrospective comparative study.
  
  
  OBJECTIVE
  To investigate the risk factors associated with upper instrumented vertebral (UIV) fractures in adult lumbar deformity.
  
  
  BACKGROUND
  Long segment lumbar fusions may lead to junctional failures. The purpose of this study was to determine factors associated with junctional failures.
  
  
  METHODS
  Twenty-seven consecutive patients from 2001 to 2008 with minimum 4 levels fused, lower instrumented vertebra (LIV) of L5 or S1, upper instrumented vertebra of T10 or distal, and no previous surgery proximal to the instrumentation were retrospectively reviewed. We describe the UIV angle, the sagittal angle of the upper instrumented vertebra with the horizontal. Patients were divided into 3 groups: group 1, 7 patients with UIV fractures; group 2, 6 patients with other proximal failures; and group 3, 14 patients with no proximal complications.
  
  
  RESULTS
  The mean number of levels fused was 5.7 (4-7), 5.2 (4-8), and 6.2 (4-8); mean age was 64.1, 61.8, and 64.1, and mean body mass index was 33.5, 30.0, and 31.6 for groups 1, 2, and 3, respectively (P > 0.05). Osteotomies were performed in 5 of 7 in group 1, 1 of 6 in group 2, and 5 of 14 in group 3. Mean follow-up was 26.3 months. The average intraoperative UIV angle (UIV0) and immediate postoperative UIV angle (UIV1) were 18.6°/15.4° for group 1, 5.7°/5.3° for group 2, and 10.3°/7.1° for group 3 (P < 0.05). Surgical revision rates were higher in group 1 (71%) compared with groups 2 (50%) and 3 (43%). Eight of 11 (73%) patients with upper instrumented vertebra of L1 or L2 had either UIV fracture or other proximal failure compared with 5 of 16 (31%) in patients with upper instrumented vertebra of T10, T11, or T12.
  
  
  CONCLUSIONS
  Our series of long lumbar fusions had a high long-term complication and revision rate. A high UIV angle on intraoperative lateral radiograph was strongly associated with UIV fractures. UIVs of L1 or L2 had a higher rate of adjacent segment or UIV failure.
authors.affiliation: Division of Orthopaedic Surgery, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada. Stephen.Lewis@uhn.on.ca
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lewis
authors.forename: Harith
authors.initials: H
authors.lastname: Abbas
authors.forename: Sooyong
authors.initials: S
authors.lastname: Chua
authors.forename: Sarah
authors.initials: S
authors.lastname: Bacon
authors.forename: Yigal
authors.initials: Y
authors.lastname: Bronstein
authors.forename: Sergey
authors.initials: S
authors.lastname: Goldstein
authors.forename: Sofia
authors.initials: S
authors.lastname: Magana
authors.forename: Kelly
authors.initials: K
authors.lastname: Sullivan
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Dold
authors.forename: Andrew
authors.initials: A
authors.lastname: Bodrogi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D016014:Linear Models; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009864:Ontario; D010027:Osteotomy / Q000009:adverse effects; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D013997:Time Factors; D017211:Treatment Failure; D055815:Young Adult