title: Evaluation of reparative cartilage after autologous chondrocyte implantation for osteochondritis dissecans: histology, biochemistry, and MR imaging.
abstract: BACKGROUND
  The aim of this study was to investigate the biochemical properties, histological and immunohistochemical appearance, and magnetic resonance (MR) imaging findings of reparative cartilage after autologous chondrocyte implantation (ACI) for osteochondritis dissecans (OCD).
  
  
  METHODS
  Six patients (mean age 20.2 +/- 8.8 years; 13-35 years) who underwent ACI for full-thickness cartilage defects of the femoral condyle were studied. One year after the procedure, a second-look arthroscopic operation was performed with biopsy of reparative tissue. The International Cartilage Repair Society (ICRS) visual histological assessment scale was used for histological assessment. Biopsied tissue was immunohistochemically analyzed with the use of monoclonal antihuman collagen type I and monoclonal antihuman collagen type II primary antibodies. Glycosaminoglycan (GAG) concentrations in biopsied reparative cartilage samples were measured by high performance liquid chromatography (HPLC). MR imaging was performed with T1- and T2-weighted imaging and three-dimensional spoiled gradient-recalled (3D-SPGR) MR imaging.
  
  
  RESULTS
  Four tissue samples were graded as having a mixed morphology of hyaline and fibrocartilage while the other two were graded as fibrocartilage. Average ICRS scores for each criterion were (I) 1.0 +/- 1.5; (II) 1.7 +/- 0.5; (III) 0.6 +/- 1.0; (IV) 3.0 +/- 0.0; (V) 1.8 +/- 1.5; and (VI) 2.5 +/- 1.2. Average total score was 10.7 +/- 2.8. On immunohistochemical analysis, the matrix from deep and middle layers of reparative cartilage stained positive for type II collagen; however, the surface layer did not stain well. The average GAG concentration in reparative cartilage was 76.6 +/- 4.2 microg/mg whereas that in normal cartilage was 108 +/- 11.2 microg/mg. Common complications observed on 3D-SPGR MR imaging were hypertrophy of grafted periosteum, edema-like signal in bone marrow, and incomplete repair of subchondral bone at the surgical site. Clinically, patients had significant improvements in Lysholm scores.
  
  
  CONCLUSIONS
  In spite of a good clinical course, reparative cartilage after ACI had less GAG concentration and was inferior to healthy hyaline cartilage in histological and immunohistochemical appearance and on MRI findings.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chiba 260-8677, Japan.
authors.forename: Takuro
authors.initials: T
authors.lastname: Moriya
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Wada
authors.forename: Atsuya
authors.initials: A
authors.lastname: Watanabe
authors.forename: Takahisa
authors.initials: T
authors.lastname: Sasho
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Pierre
authors.initials: P
authors.lastname: Mainil-Varlet
authors.forename: Hideshige
authors.initials: H
authors.lastname: Moriya
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D002358:Cartilage, Articular / Q000502:physiology*; D019902:Chondrocytes / Q000637:transplantation*; D002851:Chromatography, High Pressure Liquid; D024042:Collagen Type I / Q000276:immunology / Q000378:metabolism*; D024043:Collagen Type II / Q000276:immunology / Q000378:metabolism*; D005500:Follow-Up Studies; D006025:Glycosaminoglycans / Q000378:metabolism*; D006621:Hip Joint; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D010008:Osteochondritis Dissecans / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D020127:Recovery of Function; D014182:Transplantation, Autologous; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D024043:Collagen Type II; D006025:Glycosaminoglycans