title: The molecular composition of the extracellular matrix of the human iliolumbar ligament.
abstract: BACKGROUND
  The human iliolumbar ligament connects the transverse process of L5 to the iliac crest and contributes to lumbosacral stability and has been associated with low back pain. However, different opinions exist regarding the functional relevance of the ligament.
  
  
  OBJECTIVE
  In the present study, we analyze the regional molecular composition of the ligament extracellular matrix.
  
  
  METHODS
  Special attention is given to the attachment sites, to determine whether the ligament is subjected to a certain mechanical environment.
  
  
  METHODS
  Iliolumbar ligament samples, extending from one enthesis to the other, were removed from 11 cadavers and fixed in methanol. Cryosections were immunolabeled with a panel of antibodies directed against collagens, glycosaminoglycans, proteoglycans, matrix proteins, and neurofilament.
  
  
  RESULTS
  The mid-substance of the ligament labeled for all the molecules normally found in dense fibrous connective tissue including types I, III, and VI collagen, versican, dermatan -, chondroitin 4 -, and keratan sulfate. However, both entheses were fibrocartilaginous and labeled for type II collagen, aggrecan, and chondroitin 6- sulfate. A common feature was fat between the fiber bundles near the entheses. Occasionally this fat contained nerve fibers.
  
  
  CONCLUSIONS
  The existence of fibrocartilaginous entheses suggests that the insertion sites of the ligament are subject to both tensile and compressive loading-probably because of insertional angle changes between ligament and bone during loading. Our findings support the suggestion that the iliolumbar ligament might play an important role in the stabilization of the lumbosacral junction.
authors.affiliation: AO Research Institute, AO Foundation, Clavadelerstrasse 8, CH-7270 Davos, Switzerland.
authors.forename: Arnd F
authors.initials: AF
authors.lastname: Viehöfer
authors.affiliation: AO Research Institute, AO Foundation, Clavadelerstrasse 8, CH-7270 Davos, Switzerland; Department of Orthopaedic Surgery, Nara Medical University, 840 Shijo-cho, Kashihara-shi, Nara, 634-8522, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shinohara
authors.affiliation: AO Research Institute, AO Foundation, Clavadelerstrasse 8, CH-7270 Davos, Switzerland.
authors.forename: Christoph M
authors.initials: CM
authors.lastname: Sprecher
authors.affiliation: The Centre for Spinal Studies and Surgery, Queen's Medical Centre Campus, Derby Rd, West Block D Floor, Nottingham University Hospitals NHS Trust, Nottingham, NG7 2UH, United Kingdom.
authors.forename: Bronek M
authors.initials: BM
authors.lastname: Boszczyk
authors.affiliation: Institute of Legal Medicine, University of Rostock, St.-Georg-Straße 108, DE-18055 Rostock, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Buettner
authors.affiliation: Cardiff School of Biosciences, Museum Ave, Cardiff, CF10 3AX, United Kingdom.
authors.forename: Mike
authors.initials: M
authors.lastname: Benjamin
authors.affiliation: AO Research Institute, AO Foundation, Clavadelerstrasse 8, CH-7270 Davos, Switzerland; Anatomische Anstalt, Ludwig-Maximilians-University, Pettenkoferstr. 11, DE-80336 Munich, Germany. Electronic address: stefan.milz@med.uni-muenchen.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Milz
mesh_terms: D000293:Adolescent; D000328:Adult; D053674:Aggrecans / Q000378:metabolism; D002809:Chondroitin Sulfates; D003094:Collagen / Q000378:metabolism*; D024043:Collagen Type II / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008023:Ligaments, Articular / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011509:Proteoglycans / Q000378:metabolism*; D055815:Young Adult
chemical_list: D053674:Aggrecans; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D006025:Glycosaminoglycans; D011509:Proteoglycans; D002809:Chondroitin Sulfates; D003094:Collagen
keywords: Attachment; Enthesis; Insertion; Lumbosacral junction; Type II collagen