title: Loss in spinal motion from inclusion of a single midlumbar level in posterior spinal fusion for adolescent idiopathic scoliosis.
abstract: METHODS
  Prospective study.
  
  
  OBJECTIVE
  Evaluate the impact of the distal fusion level on overall spine motion in patients with adolescent idiopathic scoliosis.
  
  
  BACKGROUND
  In the surgical treatment of adolescent idiopathic scoliosis, the impact of incorporating a single additional distal lumbar fusion level on residual spinal motion is unclear. This study uses radiographs and computerized motion capture technology to determine whether the addition of a single lumbar level in a posterior fusion construct produces a detectable alteration in spinal motion.
  
  
  METHODS
  Twenty-three patients with adolescent idiopathic scoliosis were evaluated with standing radiographs and computerized motion analysis preoperatively and 1 year after fusion. Patients were divided into 2 groups: L1-L2 group (distal fusion ended at L1-L2) and an L3 group (distal fusion ended at L3). Cobb angle, coronal vertical alignment, sagittal vertical alignment, thoracic kyphosis, and lumbar lordosis were measured from radiographs. Three-dimensional motion data were obtained for static standing and repeated bending or twisting motions. Statistical analysis was performed with Student t test, analysis of variance, and Fisher exact methods.
  
  
  RESULTS
  Both the L1-L2 and L3 groups demonstrated loss of spinal motion compared with preoperative values. The L1-L2 group showed a significant loss of rotational motion but no significant loss of motion in the sagittal and coronal planes. The L3 group demonstrated significant loss of motion in both the coronal plane and the rotational plane. When the 2 groups were compared, the L3 group showed a significant loss of coronal plane bending (18° ± 10°, P = 0.002).
  
  
  CONCLUSIONS
  Distal extension of a posterior spinal fusion construct to include L3 results in a significant decrease in spine motion in at least one plane. Preservation of a single lumbar segment may improve overall spine motion in the short term and may have implications for the long-term health of the unfused spine.
  
  
  METHODS
  3.
authors.affiliation: *University of Connecticut †Center for Motion Analysis, and ‡Orthopaedic and Sports Medicine Research Department, Connecticut Children's Medical Center, Hartford, CT; and §Yale University, Yale-New Haven Hospital, New Haven, CT.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Lee
authors.forename: Sylvia
authors.initials: S
authors.lastname: Õunpuu
authors.forename: Matthew
authors.initials: M
authors.lastname: Solomito
authors.forename: Brian G
authors.initials: BG
authors.lastname: Smith
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Thomson
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000601:surgery; D008141:Lordosis / Q000000981:diagnostic imaging / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D009038:Motion; D011184:Postoperative Period; D057234:Preoperative Period; D011446:Prospective Studies; D011859:Radiography; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D055815:Young Adult