title: Gait stability improvement after fusion surgery for adolescent idiopathic scoliosis is influenced by corrective measures in coronal and sagittal planes.
abstract: To achieve optimal results after fusion for adolescent idiopathic scoliosis (AIS), radiographic parameters must be aligned with motion and performance. The effects of fusion on balance are poorly understood. Center of mass (COM) excursion and instantaneous interaction with center of pressure (COP) provides information about patients' balancing ability during gait. This study investigates the interaction between COM and COP (COM-COP) in AIS patients before and one year after spine fusion and determines what radiographic goals predict restoration of harmonious COM-COP. This was a prospective study that investigated sixteen adolescents with AIS curvature >30˚ requiring surgical correction. Clinical outcomes measures, X-rays, and 3D motion-capture gait analysis were collected. Sagittal and coronal COM and COP offsets and inclination angles were calculated from positional data. COM excursion was calculated as peak COM displacement based on mediolateral and vertical deviation from a line fitted to the patient's path. Radiographic parameters were measured to determine variables predictive of change in COM excursion. Post-operatively, average COM peak displacement decreased (42.6 to 13.1 mm, p=0.001) and COM peak vertical displacement remained unchanged (17.0 to 16.3 mm, p=0.472). COM-COP inclination angles reduced in the coronal, but not sagittal plane. Coronal lower extremity peak inclination angles reduced (8.8˚ to 7.5˚, p=0.025), correlating with C7 plumb-line offset (R=0.581, p=0.018). Thoracic Cobb, thoracic kyphosis, and C7 plumb-line were predictors of change in COM excursion. Mediolateral COM excursion post-surgery may reflect an attempt to reduce kinetic demands with improved spinal alignment. Although AIS correction has historically focused on the coronal plane, sagittal parameters may be more important for motion than previously theorized.
authors.affiliation: Orthopaedic Surgery, NYU Hospital for Joint Diseases, 306 East 15th Street, NY 10003 United States. Electronic address: justin.paul@nyumc.org.
authors.forename: Justin C
authors.initials: JC
authors.lastname: Paul
authors.affiliation: Orthopaedic Surgery, SUNY Downstate Medical Center,Brooklyn, NY, United States.
authors.forename: Ashish
authors.initials: A
authors.lastname: Patel
authors.affiliation: Orthopaedic Surgery, NYU Hospital for Joint Diseases, 306 East 15th Street, NY 10003 United States.
authors.forename: Kristina
authors.initials: K
authors.lastname: Bianco
authors.affiliation: Orthopaedic Surgery, SUNY Downstate Medical Center,Brooklyn, NY, United States.
authors.forename: Ellen
authors.initials: E
authors.lastname: Godwin
authors.affiliation: Orthopaedic Surgery, SUNY Downstate Medical Center,Brooklyn, NY, United States.
authors.forename: Qais
authors.initials: Q
authors.lastname: Naziri
authors.affiliation: Orthopaedic Surgery, NYU Hospital for Joint Diseases, 306 East 15th Street, NY 10003 United States.
authors.forename: Stephen
authors.initials: S
authors.lastname: Maier
authors.affiliation: Orthopaedic Surgery, NYU Hospital for Joint Diseases, 306 East 15th Street, NY 10003 United States.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
authors.affiliation: Orthopaedic Surgery, SUNY Downstate Medical Center,Brooklyn, NY, United States.
authors.forename: Carl
authors.initials: C
authors.lastname: Paulino
authors.affiliation: Orthopaedic Surgery, NYU Hospital for Joint Diseases, 306 East 15th Street, NY 10003 United States.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Errico
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007700:Kinetics; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D011312:Pressure; 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
keywords: Adolescent idiopathic scoliosis; Fusion; Gait; Kinematics; Spinal alignment