title: Cartilage repair of the ankle: first results of T2 mapping at 7.0 T after microfracture and matrix associated autologous cartilage transplantation.
abstract: BACKGROUND
  Both microfracture (MFX) and matrix associated autologous cartilage transplantation (MACT) are currently used to treat cartilage defects of the talus. T2 mapping of the ankle at 7 T has the potential to assess the collagen fibril network organization of the native hyaline cartilage and of the repair tissue (RT). This study provides first results regarding the properties of cartilage RT after MFX (mean follow-up: 113.8 months) and MACT (65.4 months).
  
  
  METHODS
  A multi-echo spin-echo sequence was used at 7 T to assess T2 maps in 10 volunteer cases, and in 10 cases after MFX and MACT each. Proton weighted morphological images and clinical data were used to ensure comparable baseline criteria.
  
  
  RESULTS
  A significant zonal variation of T2 was found in the volunteers. T2 of the superficial and the deep layer was 39.3 ± 5.9 ms and 21.1 ± 3.1 ms (zonal T2 index calculated by superficial T2/deep T2: 1.87 ± 0.2, P < 0.001). In MFX, T2 of the reference cartilage was 37.4 ± 5.0 ms and 25.3 ± 3.5 ms (1.51 ± 0.3, P < 0.001). In the RT, T2 was 43.4 ± 10.5 ms and 36.3 ± 7.7 ms (1.20 ± 0.2, P = 0.009). In MACT, T2 of the reference cartilage was 39.0 ± 9.1 ms and 27.1 ± 6.6 ms (1.45 ± 0.2, P < 0.001). In the RT, T2 was 44.6 ± 10.4 ms and 38.6 ± 7.3 ms (1.15 ± 0.1, P = 0.003). The zonal RT T2 variation differed significantly from the reference cartilage in both techniques (MFX: P = 0.004, MACT: P = 0.001).
  
  
  CONCLUSIONS
  T2 mapping at 7 T allows for the quantitative assessment of the collagen network organization of the talus. MACT and MFX yielded RT with comparable T2 properties.
authors.affiliation: Department of Orthopedics, Medical University of Vienna, Austria. stephan.domayer@meduniwien.ac.at
authors.forename: S E
authors.initials: SE
authors.lastname: Domayer
authors.forename: S
authors.initials: S
authors.lastname: Apprich
authors.forename: D
authors.initials: D
authors.lastname: Stelzeneder
authors.forename: C
authors.initials: C
authors.lastname: Hirschfeld
authors.forename: M
authors.initials: M
authors.lastname: Sokolowski
authors.forename: C
authors.initials: C
authors.lastname: Kronnerwetter
authors.forename: C
authors.initials: C
authors.lastname: Chiari
authors.forename: R
authors.initials: R
authors.lastname: Windhager
authors.forename: S
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000601:surgery*; D054544:Arthroplasty, Subchondral; D002357:Cartilage Diseases / Q000628:therapy; D002358:Cartilage, Articular / Q000473:pathology*; D019902:Chondrocytes / Q000637:transplantation*; D005260:Female; D024022:Fibrillar Collagens / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D013628:Talus / Q000473:pathology*; D014182:Transplantation, Autologous; D016896:Treatment Outcome; D014945:Wound Healing; D055815:Young Adult
chemical_list: D024022:Fibrillar Collagens