title: Ligamentum flavum hypertrophy in asymptomatic and chronic low back pain subjects.
abstract: OBJECTIVE
  To examine ligamentum flavum thickness using magnetic resonance (MR) images to evaluate its association with low back pain symptoms, age, gender, lumbar level, and disc characteristics.
  
  
  METHODS
  Sixty-three individuals were part of this IRB-approved study: twenty-seven with chronic low back pain, and thirty-six as asymptomatic. All patients underwent MR imaging and computed tomography (CT) of the lumbar spine. The MR images at the mid-disc level were captured and enlarged 800% using a bilinear interpolation size conversion algorithm that allowed for enhanced image quality. Ligamentum flavum thickness was assessed using bilateral medial and lateral measurements. Disc height at each level was measured by the least-distance measurement method in three-dimensional models created by CT images taken of the same subject. Analysis of variance and t-tests were carried out to evaluate the relationship between ligamentum flavum thickness and patient variables.
  
  
  RESULTS
  Ligamentum flavum thickness was found to significantly increase with older age, lower lumbar level, and chronic low back pain (p < 0.03). No difference in ligamentum flavum thickness was observed between right and left sided measurements, or between male and female subjects. Disc height and both ligamentum flavum thickness measurements showed low to moderate correlations that reached significance (p < 0.01). Additionally, a moderate and significant correlation between disc degeneration grade and ligamentum flavum thickness does exist (p <0.001).
  
  
  CONCLUSIONS
  By measuring ligamentum flavum thickness on MR images at two different sites and comparing degrees of disc degeneration, we found that ligamentum flavum thickness may be closely related to the pathogenesis of pain processes in the spine.
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, United States of America.
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Munns
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, United States of America.
authors.forename: Joe Y B
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, United States of America.
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Espinoza Orías
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, United States of America.
authors.forename: Ryota
authors.initials: R
authors.lastname: Takatori
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, United States of America.
authors.forename: Gunnar B J
authors.initials: GB
authors.lastname: Andersson
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, United States of America.
authors.forename: Howard S
authors.initials: HS
authors.lastname: An
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, United States of America.
authors.forename: Nozomu
authors.initials: N
authors.lastname: Inoue
mesh_terms: D000328:Adult; D000367:Age Factors; D000465:Algorithms; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D055959:Intervertebral Disc Degeneration / Q000473:pathology*; D017843:Ligamentum Flavum / Q000473:pathology*; D017116:Low Back Pain / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods