title: Partial Intervertebral Fusion Secures Successful Outcomes After Thoracoscopic Anterior Scoliosis Correction: A Low-Dose Computed Tomography Study.
abstract: METHODS
  Retrospective review of prospectively collected data.
  
  
  OBJECTIVE
  To analyze intervertebral (IV) fusion after thoracoscopic anterior spinal fusion (TASF) and explore the relationship between fusion scores and key clinical variables.
  
  
  BACKGROUND
  TASF provides comparable correction with some advantages over posterior approaches but reported mechanical complications, and their relationship to non-union and graft material is unclear. Similarly, the optimal combination of graft type and implant stiffness for effecting successful radiologic union remains undetermined.
  
  
  METHODS
  A subset of patients from a large single-center series who had TASF for progressive scoliosis underwent low-dose computed tomographic scans 2 years after surgery. The IV fusion mass in the disc space was assessed using the 4-point Sucato scale, where 1 indicates <50% and 4 indicates 100% bony fusion of the disc space. The effects of rod diameter, rod material, graft type, fusion level, and mechanical complications on fusion scores were assessed.
  
  
  RESULTS
  Forty-three patients with right thoracic major curves (mean age 14.9 years) participated in the study. Mean fusion scores for patient subgroups ranged from 1.0 (IV levels with rod fractures) to 2.2 (4.5-mm rod with allograft), with scores tending to decrease with increasing rod size and stiffness. Graft type (autograft vs. allograft) did not affect fusion scores. Fusion scores were highest in the middle levels of the rod construct (mean 2.52), dropping off by 20% to 30% toward the upper and lower extremities of the rod. IV levels where a rod fractured had lower overall mean fusion scores compared to levels without a fracture. Mean total Scoliosis Research Society (SRS) questionnaire scores were 98.9 from a possible total of 120, indicating a good level of patient satisfaction.
  
  
  CONCLUSIONS
  Results suggest that 100% radiologic fusion of the entire disc space is not necessary for successful clinical outcomes following thoracoscopic anterior selective thoracic fusion.
authors.affiliation: Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, Brisbane, Australia. Electronic address: m.izatt@qut.edu.au.
authors.forename: Maree T
authors.initials: MT
authors.lastname: Izatt
authors.affiliation: Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, Brisbane, Australia.
authors.forename: Alan
authors.initials: A
authors.lastname: Carstens
authors.affiliation: Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, Brisbane, Australia.
authors.forename: Clayton J
authors.initials: CJ
authors.lastname: Adam
authors.affiliation: Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, Brisbane, Australia.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Labrom
authors.affiliation: Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Mater Health Services, Brisbane, Australia.
authors.forename: Geoffrey N
authors.initials: GN
authors.lastname: Askin
keywords: Adolescent idiopathic scoliosis; Anterior spinal surgery; Complications; Computed tomography; Fusion grading; Interbody fusion; Intervertebral fusion; Rod diameter; Thoracoscopic scoliosis surgery