title: Kinematics of the thoracic spine in trunk lateral bending: in vivo three-dimensional analysis.
abstract: BACKGROUND
  In vivo three-dimensional kinematics of the thoracic spine in trunk lateral bending with an intact rib cage and soft tissues has not been well documented. There is no quantitative data in the literature for lateral bending in consecutive thoracic spinal segments, and there has not been consensus on the patterns of coupled motion with lateral bending.
  
  
  OBJECTIVE
  To demonstrate segmental ranges of motion (ROMs) in lateral bending and coupled motions of the thoracic spine.
  
  
  METHODS
  In vivo three-dimensional biomechanics study of the thoracic spine.
  
  
  METHODS
  Fifteen healthy male volunteers.
  
  
  METHODS
  Computed analysis by using voxel-based registration.
  
  
  METHODS
  Participants underwent computed tomography of the thoracic spine in three supine positions: neutral, right maximum lateral bending, and left maximum lateral bending. The relative motions of vertebrae were calculated by automatically superimposing an image of vertebrae in a neutral position over images in bending positions, using voxel-based registration. Mean values of lateral bending were compared among the upper (T1-T2 to T3-T4), the middle-upper (T4-T5 to T6-T7), the middle-lower (T7-T8 to T9-T10), and the lower (T10-T11 to T12-L1) parts of the spine.
  
  
  RESULTS
  At lateral bending, the mean ROM (±standard deviation) of T1 with respect to L1 was 15.6°±6.3° for lateral bending and 6.2°±4.8° for coupled axial rotation in the same direction as lateral bending. The mean lateral bending of each spinal segment with respect to the inferior adjacent vertebra was 1.4°±1.3° at T1-T2, 1.3°±1.2° at T2-T3, 1.4°±1.3° at T3-T4, 0.9°±0.9° at T4-T5, 0.8°±1.0° at T5-T6, 1.1°±1.1° at T6-T7, 1.7°±1.2° at T7-T8, 1.3°±1.2° at T8-T9, 1.6°±0.7° at T9-T10, 1.8°±0.8° at T10-T11, 2.3°±1.0° at T11-T12, and 2.2°±0.8° at T12-L1. The smallest and the largest amounts of lateral bending were observed in the middle-upper and the lower parts, respectively. There was no significant difference in lateral bending between the upper and the middle-lower parts. Coupled axial rotation of each segment was generally observed in the same direction as lateral bending. However, high variability was found at the T2-T3 to T5-T6 segments. Coupled flexion was observed at the upper and middle parts, and coupled extension was observed at the lower part.
  
  
  CONCLUSIONS
  This study revealed in vivo three-dimensional motions of consecutive thoracic spinal segments in trunk lateral bending. The thoracolumbar segments significantly contributed to lateral bending. Coupled axial rotation generally occurred in the same direction with lateral bending. However, more variability was observed in the direction of coupled axial rotation at T2-T3 to T5-T6 segments in the supine position. These results are useful for understanding normal kinematics of the thoracic spine.
authors: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: takahito-f@hotmail.co.jp.
authors: Takahito
authors: T
authors: Fujimori
authors: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Motoki
authors: M
authors: Iwasaki
authors: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Yukitaka
authors: Y
authors: Nagamoto
authors: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Yohei
authors: Y
authors: Matsuo
authors: Department of Orthopedic Surgery, Kaizuka City Hospital, 3-10-20 Hori, Kaizuka, Osaka 597-0015, Japan.
authors: Takahiro
authors: T
authors: Ishii
authors: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Tsuyoshi
authors: T
authors: Sugiura
authors: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Masafumi
authors: M
authors: Kashii
authors: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Tsuyoshi
authors: T
authors: Murase
authors: Department of Orthopedic Biomaterial Science, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Kazuomi
authors: K
authors: Sugamoto
authors: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors: Hideki
authors: H
authors: Yoshikawa
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D016059:Range of Motion, Articular; D012399:Rotation; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology; D014057:Tomography, X-Ray Computed
keywords: Biomechanics; Coupled motion; In vivo three-dimensional; Lateral bending; Scoliosis; Thoracic spine