title: Factors associated with the thickness of the ligamentum flavum: is ligamentum flavum thickening due to hypertrophy or buckling?
abstract: METHODS
  Ligamentum flavum (LF) thickness was measured by using lumbar magnetic resonance imaging in patients with low back or leg pain.
  
  
  OBJECTIVE
  This study investigated whether LF thickening is due to hypertrophy or buckling related to disc degeneration and examined the correlations between the thickness of the LF and age, sex, body mass index (BMI), degree of pain, lumbar spinal stenosis (LSS), and disc herniation.
  
  
  BACKGROUND
  "LF thickness" and "LF hypertrophy" are used interchangeably in the literature, although they are not necessarily the same thing. Thickness may increase by buckling without a change in the mass of the LF, and whether LF thickening is due to tissue hypertrophy or buckling remains controversial.
  
  
  METHODS
  The thickness of 896 LFs at the L2-L3, L3-L4, L4-L5, and L5-S1 levels of 224 (mean age, 47.8 ± 16.7 yrs) patients was measured prospectively on axial T1-weighed magnetic resonance images, obtained at the facet joint level. The presence of disc degeneration, spinal stenosis, and disc herniation was evaluated.
  
  
  RESULTS
  At all of the levels investigated, LF thickness was significantly greater in patients with grades IV to V degeneration compared with the patients with grades I to III degeneration (P < 0.05). LF thickness at all levels increased significantly with age (P < 0.05). Sex and the degree of pain were not correlated with the thickness of the LF. Patients with a BMI of 25 kg/m or greater had the thickest LF at the L3-L4 level (P < 0.01). LF thickness was significantly greater at the L2-L3, L3-L4, and L4-L5 levels in subjects with LSS and significantly greater at all levels in subjects with disc herniation (P < 0.05).
  
  
  CONCLUSIONS
  Thickening of the LF is correlated with disc degeneration, aging, BMI, LSS, spinal level, and disc herniation. The authors concluded that thickening of the LF is due to buckling of the LF into the spinal canal secondary to disc degeneration more than to LF hypertrophy. Sex and the degree of pain were not correlated with the thickness of the LF.
authors.affiliation: Department of Radiology, Baskent University Medical School, Adana, Turkey. naimeto@yahoo.com
authors.forename: Naime
authors.initials: N
authors.lastname: Altinkaya
authors.forename: Tulin
authors.initials: T
authors.lastname: Yildirim
authors.forename: Senay
authors.initials: S
authors.lastname: Demir
authors.forename: Ozlem
authors.initials: O
authors.lastname: Alkan
authors.forename: Feyzi Birol
authors.initials: FB
authors.lastname: Sarica
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001416:Back Pain / Q000150:complications; D015992:Body Mass Index; D005260:Female; D006801:Humans; D006984:Hypertrophy / Q000209:etiology / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000473:pathology*; D007405:Intervertebral Disc Displacement / Q000150:complications / Q000473:pathology; D007866:Leg / Q000503:physiopathology; D017843:Ligamentum Flavum / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000503:physiopathology; D010147:Pain Measurement; D011859:Radiography; D012307:Risk Factors; D012447:Sacrum / Q000000981:diagnostic imaging / Q000473:pathology; D012720:Severity of Illness Index; D013130:Spinal Stenosis / Q000150:complications / Q000473:pathology; D055815:Young Adult