title: Immunohistochemical composition of the human lunotriquetral interosseous ligament.
abstract: OBJECTIVE
  The human lunotriquetral ligament (LTL) is a functionally important intrinsic hand ligament, which is assumedly subjected to insertion angle changes at the entheses during movement. To clarify whether the current model of the ligament's mechanical environment is reflected in its structural composition, we determined the regional distribution of extracellular matrix-related antigens.
  
  
  METHODS
  The extracellular matrix was immunohistochemically investigated in 12 LTLs from both wrists of 6 human donors (Mean age: 60 y).
  
  
  RESULTS
  The dorsal, proximal, and volar portions of the ligament immunolabeled for type I, III collagen and versican. Both entheses labeled strongly for type II collagen, aggrecan, and link protein and were distinctly cartilaginous. The ligament midsubstance was positive for collagen II in 30%, for aggrecan in 40%, and for keratocan and lumican in 100% of specimens. In contrast, keratocan and lumican were absent from the fibrocartilaginous entheses and the articular cartilage. Ligament insertion at a carpal bone occurs either directly through fibrocartilage or indirectly through a bilayered configuration of fibrocartilage and hyaline-like cartilage. The hyaline-like cartilage is continuous with the neighboring articular cartilage.
  
  
  CONCLUSIONS
  The LTL has an extracellular matrix comparable with that of ligaments experiencing a combination of tensile and shear/compressive load at the attachment sites. All regions of the LTL exhibit fibrocartilaginous entheses; purely fibrous attachment sites are rare. The ligament midsubstance shows a more fibrous phenotype than the entheses and expresses keratocan and lumican, which previously have not been recorded in any human hand ligament.
authors.affiliation: AO Foundation, AO Research Institute, Davos, Switzerland.
authors.forename: Piyawan
authors.initials: P
authors.lastname: Chatuparisute
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shinohara
authors.forename: Chlodwig
authors.initials: C
authors.lastname: Kirchhoff
authors.forename: Florian
authors.initials: F
authors.lastname: Fischer
authors.forename: Stefan
authors.initials: S
authors.lastname: Milz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D053674:Aggrecans / Q000378:metabolism*; D001344:Autopsy; D015415:Biomarkers / Q000378:metabolism; D002356:Cartilage / Q000033:anatomy & histology / Q000378:metabolism; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism*; D003094:Collagen / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007632:Keratan Sulfate / Q000378:metabolism*; D008023:Ligaments, Articular / Q000033:anatomy & histology / Q000378:metabolism*; D000071234:Lumican; D008297:Male; D008875:Middle Aged; D020033:Protein Isoforms / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism*; D053675:Versicans / Q000378:metabolism*
chemical_list: D053674:Aggrecans; D015415:Biomarkers; D011508:Chondroitin Sulfate Proteoglycans; C490948:KERA protein, human; C000604306:LUM protein, human; D000071234:Lumican; D020033:Protein Isoforms; D011509:Proteoglycans; D053675:Versicans; D003094:Collagen; D007632:Keratan Sulfate