title: Fibrocartilage in various regions of the human glenoid labrum. An immunohistochemical study on human cadavers.
abstract: OBJECTIVE
  The nature and the distribution of fibrocartilage at the human glenoid labrum are unclear, and a better understanding may help to restore its function in open and arthroscopic Bankart repair. Aim of this study was to describe the fibrocartilage extent within the labrum at clinically relevant sites of the glenoid in order to relate the molecular composition of the labrum to its mechanical environment.
  
  
  METHODS
  Twelve fresh frozen human cadaveric shoulders (mean age 38 years) were obtained, and sections perpendicular to the glenoid rim at the 12, 2, 3, 4, 6 and 9 o' clock position were labelled with antibodies against collagen I and II, aggrecan and link protein.
  
  
  RESULTS
  A fibrocartilaginous transition zone with a characteristic collagen fibre orientation was found in 81% of cases, evenly distributed (83-92%) around the glenoid rim. The percentage of labrum cross-sectional area comprised of fibrocartilage averaged 28% and ranged from 26% at 12 o'clock on the glenoid clock face to 30% at 3 o'clock. The highest amount of fibrocartilage (82%) was found in the region neighbouring the hyaline articular cartilage. In the region beyond the bony edge of the glenoid, fibrocartilage cross-sectional area did not exceed 12-17%.
  
  
  CONCLUSIONS
  Fibrocartilage is present at all examined positions around the glenoid rim and constitutes up to 1/3 of the cross-sectional area of the labrum. In turn, the percentage of fibrocartilage in different regions of its cross-section varies considerably. The findings suggest that the penetration of fibrocartilaginous tissue may be reduced by avoiding the highly fibrocartilage transition zone during restoration of labral detachment.
authors.affiliation: AO Research Institute Davos, AO Foundation, Davos, Switzerland. ben.ockert@med.uni-muenchen.de
authors.forename: Ben
authors.initials: B
authors.lastname: Ockert
authors.forename: Volker
authors.initials: V
authors.lastname: Braunstein
authors.forename: Christoph M
authors.initials: CM
authors.lastname: Sprecher
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shinohara
authors.forename: Stefan
authors.initials: S
authors.lastname: Milz
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D051445:Fibrocartilage / Q000033:anatomy & histology* / Q000378:metabolism; D061165:Glenoid Cavity; D006801:Humans; D007150:Immunohistochemistry; D011509:Proteoglycans / Q000378:metabolism; D012785:Shoulder Joint / Q000033:anatomy & histology* / Q000378:metabolism; D000099249:Proteoglycan Link Protein
chemical_list: D053674:Aggrecans; D015415:Biomarkers; D024042:Collagen Type I; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D000099249:Proteoglycan Link Protein