title: Light and electron microscopy of hydroxyapatite depositions in the ligamentum flavum.
abstract: METHODS
  Ligamenta flava obtained from 24 patients who had undergone surgery for degenerative spinal diseases were investigated regarding the histopathology of hydroxyapatite crystal depositions.
  
  
  OBJECTIVE
  Light and electron microscopy and energy dispersive x-ray microanalysis were done to clarify the cause and process of hydroxyapatite crystal depositions in the ligament.
  
  
  BACKGROUND
  No reports have been made regarding the cause of calcification in the ligamenta flava induced by hydroxyapatite crystal depositions.
  
  
  METHODS
  Samples were fixed in 10% formalin and 2.5% glutaraldehyde for light and electron microscopy. Energy dispersive x-ray microanalysis was done to detect calcium and phosphate hydroxyapatite crystal deposition areas.
  
  
  RESULTS
  Hydroxyapatite crystals, which occasionally formed clusters, existed in the connective tissue of the dural side around abundant profiles of growing capillaries. Hydroxyapatite crystals showed needle shaped figures, and the x-ray microanalysis revealed that the ratio of calcium to phosphate was about 1.66:1. A decrease or loss of collagenous and elastic fibers was prominent in these hydroxyapatite deposition areas.
  
  
  CONCLUSIONS
  Hydroxyapatite crystal depositions occur around the growing capillaries in the dural side of the ligamenta flava.
authors.affiliation: Department of Orthopedic Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Hijioka
authors.forename: K
authors.initials: K
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Yokoyama
authors.forename: Y
authors.initials: Y
authors.lastname: Kanazawa
mesh_terms: D000328:Adult; D000368:Aged; D002196:Capillaries / Q000473:pathology; D017886:Durapatite / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D005260:Female; D006801:Humans; D017843:Ligamentum Flavum / Q000737:chemistry* / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged
chemical_list: D017886:Durapatite