title: Treatment of cartilage defects by subchondral drilling combined with covering with atelocollagen membrane induces osteogenesis in a rat model.
abstract: BACKGROUND
  The coverage of the atelocollagen membrane at the chondral defect after subchondral drilling might improve the beneficial effects for cartilage repair because of the prevention of scattering and accumulation of cells and growth factors from bone marrow within the chondral defect. On the other hand, it might block cells and factors derived from the synovium or cause high pressure in the chondral defect, resulting in prevention of cells and growth factors gushing out from the bone marrow, which leads to disadvantages for cartilage repair.
  
  
  METHODS
  We tested this hypothesis in a 2-mm-diameter chondral defect created in the articular cartilage of the patellar groove in a rat models. Defects were left untreated, or were drilled or drilled and covered with an atelocollagen membrane; healing was evaluated by histology and gene expression analysis using real-time polymerase chain reaction and immunohistochemistry.
  
  
  RESULTS
  Membrane coverage induced bone tissue ingrowth into the punched chondral defect. At 1 week, expression of TGFβ, Sox9, Runx2, osteocalcin, Col1a1, and Col2a1 in the drilling group was significantly higher than in the covering group. At 4 weeks, expressions of TGFβ, Runx2, and Col1a1 were all significantly higher in the drilling group, while Sox9, osteocalcin, and Col2a1 were significantly higher in the covering group. Immunohistochemistry demonstrated Sox9, osteocalcin, and type II collagen on the bony reparative tissue in the covering group.
  
  
  CONCLUSIONS
  These results suggest that the atelocollagen membrane coverage resulted in inhibition of cartilage repair.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. michiosprinter@yahoo.co.jp
authors.forename: Michio
authors.initials: M
authors.lastname: Hamanishi
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nakasa
authors.forename: Naosuke
authors.initials: N
authors.lastname: Kamei
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kazusa
authors.forename: Goki
authors.initials: G
authors.lastname: Kamei
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Ochi
mesh_terms: D000818:Animals; D054544:Arthroplasty, Subchondral; D002356:Cartilage / Q000187:drug effects / Q000502:physiology; D002357:Cartilage Diseases / Q000628:therapy*; D003094:Collagen / Q000494:pharmacology / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D008297:Male; D010012:Osteogenesis / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012038:Regeneration / Q000187:drug effects
chemical_list: C059821:atelocollagen; D003094:Collagen
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