title: An immunohistochemical study of the dorsal capsule of the lumbar and thoracic facet joints.
abstract: METHODS
  The molecular composition of the extracellular matrix in the dorsal capsules of lumbar and thoracic facet joints was analyzed immunohistochemically.
  
  
  OBJECTIVE
  To determine whether the immunohistochemical profile of the lumbar joint capsule suggests a role of the capsule in limiting axial rotation of the lumbar motion segment.
  
  
  BACKGROUND
  During axial rotation of the lumbar vertebrae, the axis of rotation shifts toward the facet joints in the direction of rotation. Thus, the capsule of the opposing joint should become tensed and wrap around the inferior articular process. Previous studies suggest that wrap-around ligaments are fibrocartilaginous. However, thoracic joint capsules are largely shielded from such loading and should be purely fibrous.
  
  
  METHODS
  Dorsal capsules were removed from lumbar and thoracic facet joints of six adult cadavers. Specimens were immunolabeled with monoclonal antibodies for collagens, chondroitin, dermatan and keratan sulfates, versican, tenascin, aggrecan and link protein. Antibody binding was detected using the Vectastain ABC 'Elite' peroxidase kit (Vector Laboratories, Inc., Burlingame, CA).
  
  
  RESULTS
  Both lumbar and thoracic joint capsules immunolabelled for most glycosaminoglycans and for Type I, III and VI collagens. However, labeling for Type II collagen, chondroitin-6-sulfate, aggrecan, and link protein was restricted to lumbar capsules. Such labeling was constantly seen at entheses and occasionally in the midsubstance.
  
  
  CONCLUSIONS
  The molecular composition of the lumbar joint capsule suggests that it acts as a fibrocartilaginous, 'wrap-around' ligament that withstands compression in addition to tension during torsional movements of the lumbar spine. It wraps around the inferior articular process as rotation occurs and limits further movement.
authors.affiliation: Neurochirurgische AbteilungBerufsgenossenschaftliche Unfallklinik MurnauProfessor-Küntscher-Strass 8D-82418 Murnau, Germany.B.Boszczyk@GMX.net
authors.forename: B M
authors.initials: BM
authors.lastname: Boszczyk
authors.forename: A A
authors.initials: AA
authors.lastname: Boszczyk
authors.forename: R
authors.initials: R
authors.lastname: Putz
authors.forename: A
authors.initials: A
authors.lastname: Büttner
authors.forename: M
authors.initials: M
authors.lastname: Benjamin
authors.forename: S
authors.initials: S
authors.lastname: Milz
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis*; D002102:Cadaver; D003094:Collagen / Q000032:analysis; D005109:Extracellular Matrix / Q000737:chemistry*; D005260:Female; D006025:Glycosaminoglycans / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D017746:Joint Capsule / Q000033:anatomy & histology / Q000737:chemistry*; D008159:Lumbar Vertebrae / Q000033:anatomy & histology / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D013904:Thoracic Vertebrae / Q000033:anatomy & histology / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D006025:Glycosaminoglycans; D003094:Collagen