title: Analysis of the Relationship between Hypertrophy of the Ligamentum Flavum and Lumbar Segmental Motion with Aging Process.
abstract: METHODS
  Retrospective cross-sectional study.
  
  
  OBJECTIVE
  To investigate the relationship between ligamentum flavum (LF) hypertrophy and lumbar segmental motion.
  
  
  BACKGROUND
  The pathogenesis of LF thickening is unclear and whether the thickening results from tissue hypertrophy or buckling remains controversial.
  
  
  METHODS
  296 consecutive patients underwent assessment of the lumbar spine by radiographic and magnetic resonance imaging (MRI). Of these patients, 39 with normal L4-L5 disc height were selected to exclude LF buckling as one component of LF hypertrophy. The study group included 27 men and 12 women, with an average age of 61.2 years (range, 23-81 years). Disc degeneration and LF thickness were quantified on MRI. Lumbar segmental spine instability and presence of a vacuum phenomenon were identified on radiographic images.
  
  
  RESULTS
  The distribution of disc degeneration and LF thickness included grade II degeneration in 4 patients, with a mean LF thickness of 2.43±0.20 mm; grade III in 10 patients, 3.01±0.41 mm; and grade IV in 25 patients, 4.16±1.12 mm. LF thickness significantly increased with grade of disc degeneration and was significantly correlated with age (r=0.55, p<0.01). Logistic regression analysis identified predictive effects of segmental angulation (odds ratio [OR]=1.55, p=0.014) and age (OR=1.16, p=0.008).
  
  
  CONCLUSIONS
  Age-related increases in disc degeneration, combined with continuous lumbar segmental flexion-extension motion, leads to the development of LF hypertrophy.
authors.affiliation: Department of Orthopaedic Surgery, Oita University Faculty of Medicine, Yufu, Japan.
authors.forename: Toyomi
authors.initials: T
authors.lastname: Yoshiiwa
authors.affiliation: Department of Orthopaedic Surgery, Oita University Faculty of Medicine, Yufu, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
authors.affiliation: Department of Orthopaedic Surgery, Oita University Faculty of Medicine, Yufu, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Kawano
authors.affiliation: Department of Orthopaedic Surgery, Oita University Faculty of Medicine, Yufu, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Ikeda
authors.affiliation: Department of Orthopaedic Surgery, Oita University Faculty of Medicine, Yufu, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsumura
keywords: Disc degeneration; Ligamentum flavum; Lumbar spine; Spinal canal stenosis