title: Progressive junctional kyphosis at the caudal end of lumbar instrumented fusion: etiology, predictors, and treatment.
abstract: METHODS
  Clinical case series.
  
  
  OBJECTIVE
  To describe a series of patients with progressive sagittal decompensation caused by failure at the caudal end of an instrumented lumbar fusion.
  
  
  BACKGROUND
  Lumbar kyphosis in association with global sagittal decompensation can be a disabling problem, particularly as a late complication of distraction instrumentation. Although kyphosis at the rostral end of instrumented fusions secondary to adjacent segment degeneration has been well described, substantially less has been documented about failure and kyphosis at the caudal end.
  
  
  METHODS
  Patients who have a progressive lumbar kyphosis and sagittal decompensation requiring operative revision were retrospectively reviewed, and radiographic measurements of lumbar lordosis and sagittal balance were performed to study this problem.
  
  
  RESULTS
  There were 13 patients identified. The most common mode of caudal junctional decompensation was related to failure of the most distal fixation. Sagittal decompensation occurred even in the presence of satisfactory lumbar lordosis. Revision surgery and improved sagittal balance were achieved typically using the technique of pedicle subtraction osteotomy and extension of the instrumentation to the sacrum. Osteoporosis, hip osteoarthritis, and substance abuse were commonly observed associations.
  
  
  CONCLUSIONS
  Fixation failure at the caudal end of lumbar-instrumented fusion should be considered in patients with progressive sagittal decompensation. The high potential for failure of L5 pedicle screws after the index surgery warrants serious consideration of extending such fusions into the sacrum/ilium.
authors.affiliation: Division of Spine, Department of Orthopaedics, University of British Columbia Vancouver, Canada.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Kwon
authors.forename: Hossein
authors.initials: H
authors.lastname: Elgafy
authors.forename: Ory
authors.initials: O
authors.lastname: Keynan
authors.forename: Charles G
authors.initials: CG
authors.lastname: Fisher
authors.forename: Michael C
authors.initials: MC
authors.lastname: Boyd
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Paquette
authors.forename: Marcel F
authors.initials: MF
authors.lastname: Dvorak
mesh_terms: D000368:Aged; D001863:Bone Screws / Q000009:adverse effects; D004868:Equipment Failure; D005260:Female; D006801:Humans; D016268:Internal Fixators; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011859:Radiography; D012086:Reoperation; D013123:Spinal Fusion / Q000009:adverse effects*