title: Matrix-based autologous chondrocyte implantation for cartilage repair: noninvasive monitoring by high-resolution magnetic resonance imaging.
abstract: OBJECTIVE
  Monitoring of articular cartilage repair after matrix-associated autologous chondrocyte implantation (MACI) by a new grading and point-scale system based on noninvasive cartilage-specific magnetic resonance imaging (MRI) protocol.
  
  
  METHODS
  In 20 patients, postoperative high-resolution MRI follow-up examinations at 4, 12, 24 and 52 weeks after matrix-based ACI for cartilage repair were initiated. The repair tissue was described with separate variables: degree of defect repair in width and length, surface, structure and signal intensity of the repair tissue, and status of the subchondral lamina and bone. For these variables, a grading system with point-scale evaluation was applied, and the mean average values were calculated for every follow-up MR exam of each patient.
  
  
  RESULTS
  In 10 patients, an incomplete filling of the defect improved to complete filling (6 patients) or less incomplete (4 patients) filling of the defect. Three cases of implant hypertrophy returned to normal within 1 year. Complete filling of the defect by repair tissue was found in 2 patients from the beginning. Integration was complete in 10 cases. Improvement of incomplete to complete integration was found in 3 patients. The signal intensity of the implant developed to native cartilage signal in 13 patients. The mean average values increased from the 4th to the 52 nd week in 17 of 20 patients and decreased in 3 of 20 patients.
  
  
  CONCLUSIONS
  High-resolution MRI provides a noninvasive tool for monitoring the development of cartilage repair tissue in MACI over time and helps to differentiate abnormal repair tissue from a normal maturation process.
authors.affiliation: Department of Radiology, University Hospital of Vienna, Medical University of Vienna, A-1090 Vienna, Austria. siegfried.trattnig@meduniwein.ac.at
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ba-Ssalamah
authors.forename: Katja
authors.initials: K
authors.lastname: Pinker
authors.forename: Christina
authors.initials: C
authors.lastname: Plank
authors.forename: Vilmos
authors.initials: V
authors.lastname: Vecsei
authors.forename: Stefan
authors.initials: S
authors.lastname: Marlovits
mesh_terms: D000328:Adult; D002357:Cartilage Diseases / Q000628:therapy*; D002358:Cartilage, Articular; D019902:Chondrocytes / Q000637:transplantation*; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000628:therapy*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D014182:Transplantation, Autologous; D016896:Treatment Outcome