title: Assessment of articular cartilage repair tissue after matrix-associated autologous chondrocyte transplantation or the microfracture technique in the ankle joint using diffusion-weighted imaging at 3 Tesla.
abstract: OBJECTIVE
  The objective was to compare patients after matrix-associated autologous chondrocyte transplantation (MACT) and microfracture therapy (MFX) of the talus using diffusion-weighted imaging (DWI), with morphological and clinical scoring.
  
  
  METHODS
  Twenty patients treated with MACT or MFX (10 per group) were examined using 3 T magnetic resonance imaging (MRI) at 48 ± 21.5 and 59.6 ± 23 months after surgery, respectively. For comparability, patients from each group were matched by age, body mass index, and follow-up. American Orthopaedic Foot and Ankle Society (AOFAS) score served as clinical assessment tool pre- and postoperatively. DWI was obtained using a partially balanced, steady-state gradient echo pulse sequence, as well as the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score, based on a 2D proton density-weighted turbo spin-echo sequence and a 3D isotropic true fast imaging with steady-state precession sequence. Semi-quantitative diffusion quotients were calculated after region of interest analysis of repair tissue (RT) and healthy control cartilage, and compared among both groups.
  
  
  RESULTS
  The mean AOFAS score improved significantly (P = 0.001) for both groups (MACT: 48.8 ± 20.4-83.6 ± 9.7; MFX: 44.3 ± 16.5-77.6 ± 13.2). No differences in the AOFAS (P = 0.327) and MOCART (P = 0.720) score were observed between MACT and MFX postoperatively. DWI distinguished between healthy cartilage and cartilage RT in the MFX group (P = 0.016), but not after MACT treatment (P = 0.105). Significant correlations were found between MOCART score and DWI index after MFX (Pearson: -0.648; P = 0.043), and between the diffusivity and longer follow-up interval in MACT group (Pearson: -0.647, P = 0.043).
  
  
  CONCLUSIONS
  Whereas conventional scores reveal a similar outcome after MACT or MFX treatment in the ankle joint, DWI was able to distinguish between different RT qualities, as reported histologically for these diverse surgical procedures.
authors.affiliation: MR Centre of Excellence, Department of Radiology, Medical University of Vienna, Austria. sebastian.apprich@meduniwien.ac.at
authors.forename: S
authors.initials: S
authors.lastname: Apprich
authors.forename: S
authors.initials: S
authors.lastname: Trattnig
authors.forename: G H
authors.initials: GH
authors.lastname: Welsch
authors.forename: I M
authors.initials: IM
authors.lastname: Noebauer-Huhmann
authors.forename: M
authors.initials: M
authors.lastname: Sokolowski
authors.forename: M
authors.initials: M
authors.lastname: Sokolwski
authors.forename: C
authors.initials: C
authors.lastname: Hirschfeld
authors.forename: D
authors.initials: D
authors.lastname: Stelzeneder
authors.forename: S
authors.initials: S
authors.lastname: Domayer
mesh_terms: D000328:Adult; D016512:Ankle Injuries / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D000843:Ankle Joint / Q000473:pathology / Q000502:physiology / Q000601:surgery*; D054544:Arthroplasty, Subchondral; D002358:Cartilage, Articular / Q000473:pathology / Q000502:physiology / Q000601:surgery*; D019902:Chondrocytes / Q000637:transplantation*; D003430:Cross-Sectional Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D010008:Osteochondritis Dissecans / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014945:Wound Healing / Q000502:physiology; D055815:Young Adult