title: In vivo dynamic changes of dimensions in the lumbar intervertebral foramen.
abstract: BACKGROUND
  Previous studies have reported position-dependent changes of the lumbar intervertebral foramen (LIVF) dimensions at different static flexion-extension postures. However, the changes of the LIVF dimensions during dynamic body motion have not been reported.
  
  
  OBJECTIVE
  The objective of this study was to investigate the in vivo dimensions of the LIVF during a dynamic weight-lifting activity.
  
  
  METHODS
  This was a retrospective study.
  
  
  METHODS
  Ten asymptomatic subjects were recruited for this study. Three-dimensional (3D) vertebral models of the lumbar segments from L2 to S1 were constructed for each subject using magnetic resonance images. The lumbar spine was then imaged using a dual fluoroscopic imaging system as the subject performed a dynamic weight-lifting activity from an upper body position of 45° to a maximal extension position. The in vivo positions of the vertebrae along the motion path were reproduced using the 3D vertebral models and the fluoroscopic images. The minimal area, height, and width of each LIVF during the dynamic body motion were analyzed.
  
  
  RESULTS
  The LIVF area and width monotonically decreased with lumbar extension at all levels except L5-S1 (p<.05). On average, the LIVF area decreased by 7.4±6.7%, 10.8±7.7%, and 10.0±8.0% at the L2-L3, L3-L4, and L4-L5 levels, respectively, from the flexion to the upright standing position, and by 6.4±5.0%, 7.7±7.4%, and 5.1±5.1%, respectively, from the upright standing to the extension position. The LIVF height remained relatively constant at all segments during the dynamic activity. The foramen area, height, and width of the L5-S1 remained relatively constant throughout the activity.
  
  
  CONCLUSIONS
  Human lumbar foramen dimensions show segment-dependent characteristics during the dynamic weight-lifting activity.
authors: Bioengineering Laboratory, Department of Orthopaedic Surgery, Harvard Medical School/Massachusetts General Hospital, 55 Fruit St, GRJ 1215, Boston, MA 02114, USA; Department of Spinal Surgery, Second Xiangya Hospital and Central South University, 139 Middle of Renmin Road, Changsha, Hunan, 410011, P.R. China.
authors: Weiye
authors: W
authors: Zhong
authors: Bioengineering Laboratory, Department of Orthopaedic Surgery, Harvard Medical School/Massachusetts General Hospital, 55 Fruit St, GRJ 1215, Boston, MA 02114, USA.
authors: Sean J
authors: SJ
authors: Driscoll
authors: Bioengineering Laboratory, Department of Orthopaedic Surgery, Harvard Medical School/Massachusetts General Hospital, 55 Fruit St, GRJ 1215, Boston, MA 02114, USA.
authors: Tsung-Yuan
authors: TY
authors: Tsai
authors: Bioengineering Laboratory, Department of Orthopaedic Surgery, Harvard Medical School/Massachusetts General Hospital, 55 Fruit St, GRJ 1215, Boston, MA 02114, USA.
authors: Shaobai
authors: S
authors: Wang
authors: Bioengineering Laboratory, Department of Orthopaedic Surgery, Harvard Medical School/Massachusetts General Hospital, 55 Fruit St, GRJ 1215, Boston, MA 02114, USA; Department of Orthopedic Surgery, the First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, Jiangsu, 215006, China.
authors: Haiqing
authors: H
authors: Mao
authors: Bioengineering Laboratory, Department of Orthopaedic Surgery, Harvard Medical School/Massachusetts General Hospital, 55 Fruit St, GRJ 1215, Boston, MA 02114, USA.
authors: Thomas D
authors: TD
authors: Cha
authors: Bioengineering Laboratory, Department of Orthopaedic Surgery, Harvard Medical School/Massachusetts General Hospital, 55 Fruit St, GRJ 1215, Boston, MA 02114, USA.
authors: Kirkham B
authors: KB
authors: Wood
authors: Bioengineering Laboratory, Department of Orthopaedic Surgery, Harvard Medical School/Massachusetts General Hospital, 55 Fruit St, GRJ 1215, Boston, MA 02114, USA. Electronic address: gli1@partners.org.
authors: Guoan
authors: G
authors: Li
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology*; D008161:Lumbosacral Region / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011187:Posture; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012399:Rotation; D013314:Stress, Mechanical; D014891:Weight Lifting / Q000502:physiology*
keywords: Dual-fluoroscopy; Foramen area; In-vivo; Lumbar intervertebral foramen; Lumbar kinematics; Lumbar stenosis; Weight-lifting activity