title: Effect of Lowest Instrumented Vertebra on Trunk Mobility in Patients With Adolescent Idiopathic Scoliosis Undergoing a Posterior Spinal Fusion.
abstract: METHODS
  Prospective.
  
  
  OBJECTIVE
  The goal of this study was to evaluate the effect of posterior spinal fusion surgery terminating at different lowest instrumented vertebrae (LIV) on trunk mobility in individuals with adolescent idiopathic scoliosis (AIS).
  
  
  BACKGROUND
  Posterior spinal fusion with instrumentation is the standard surgical technique employed in AIS for correcting spine deformities with Cobb angles exceeding 50°. Surgical correction of curve deformity reduces trunk mobility and range of motion. However, conflicting findings from previous studies investigating the impact of different LIV levels on the reduction in trunk mobility after surgery have been reported.
  
  
  METHODS
  The study was designed as a prospective study with 47 patients (7 males and 40 females) with AIS who underwent posterior spinal fusion. Patients were classified into 5 groups based on their surgical LIV level (ie, T12, L1, L2, L3, and L4). Trunk flexion-extension (sagittal plane), lateral bending (coronal plane), and axial rotation (transverse plane) kinematics were assessed during preoperative, 1 year postoperative, and 2 years postoperative evaluation visits.
  
  
  RESULTS
  There were postoperative reductions of 41%, 51%, and 59% in trunk range of motion in the sagittal, coronal, and transverse planes, respectively (p < .0001). A trend toward greater postoperative reductions in peak forward flexion at more distal LIVs was observed (p = .04).
  
  
  CONCLUSIONS
  Fusion reduces trunk mobility in the sagittal, coronal, and transverse planes. More distal LIV fusions limit peak forward flexion to a greater extent which is considered clinically significant. After fusion, the reductions seen in axial rotation, lateral bending, and backward extension do not differ significantly at more distal LIVs.
authors.affiliation: College of Engineering, Marquette University, Milwaukee, WI, USA.
authors.forename: Ubong I
authors.initials: UI
authors.lastname: Udoekwere
authors.affiliation: Motion Analysis Laboratory, Shriners Hospitals for Children, Chicago, IL, USA; College of Health Sciences, Physical Therapy Program, Midwestern University, Downers Grove, IL, USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Krzak
authors.affiliation: Motion Analysis Laboratory, Shriners Hospitals for Children, Chicago, IL, USA. Electronic address: agraf@shrinenet.org.
authors.forename: Adam
authors.initials: A
authors.lastname: Graf
authors.affiliation: Motion Analysis Laboratory, Shriners Hospitals for Children, Chicago, IL, USA.
authors.forename: Sahar
authors.initials: S
authors.lastname: Hassani
authors.affiliation: Division of Biostatistics, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Sergey
authors.initials: S
authors.lastname: Tarima
authors.affiliation: Motion Analysis Laboratory, Shriners Hospitals for Children, Chicago, IL, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Riordan
authors.affiliation: Division of Orthopaedic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Sturm
authors.affiliation: Motion Analysis Laboratory, Shriners Hospitals for Children, Chicago, IL, USA.
authors.forename: Kim W
authors.initials: KW
authors.lastname: Hammerberg
authors.affiliation: Motion Analysis Laboratory, Shriners Hospitals for Children, Chicago, IL, USA.
authors.forename: Purnendu
authors.initials: P
authors.lastname: Gupta
authors.affiliation: College of Osteopathic Medicine, Midwestern University, Downers Grove, IL, USA.
authors.forename: Alireza K
authors.initials: AK
authors.lastname: Anissipour
authors.affiliation: College of Engineering, Marquette University, Milwaukee, WI, USA; Motion Analysis Laboratory, Shriners Hospitals for Children, Chicago, IL, USA; Division of Biostatistics, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Harris
keywords: Adolescent idiopathic scoliosis; Lowest instrumented vertebra; Posterior spinal fusion; Range of motion; Trunk mobility