title: MRI T1ρ and T2 mapping for the assessment of articular cartilage changes in patients with medial knee osteoarthritis after hemicallotasis osteotomy.
abstract: OBJECTIVE
  The purpose of this study was to clarify the appearance of the reparative tissue on the articular surface and to analyse the properties of the reparative tissue after hemicallotasis osteotomy (HCO) using MRI T1ρ and T2 mapping.
  
  
  METHODS
  Coronal T1ρ and T2 mapping and three-dimensional gradient-echo images were obtained from 20 subjects with medial knee osteoarthritis. We set the regions of interest (ROIs) on the full-thickness cartilage of the medial femoral condyle (MFC) and medial tibial plateau (MTP) of the knee and measured the cartilage thickness (mm) and T1ρ and T2 relaxation times (ms). Statistical analysis of time-dependent changes in the cartilage thickness and the T1ρ and T2 relaxation times was performed using one-way analysis of variance, and Scheffe's test was employed for post hoc multiple comparison.
  
  
  RESULTS
  The cartilage-like repair tissue appeared on the cartilage surface of the medial compartment post-operatively, and the cartilage thickness showed a significant increase between the pre-operative and one-year post-operative time points (MFC; p = 0.003, MTP; p < 0.001). The T1ρ values of the cartilage-like repair tissue showed no difference over time, however, the T2 values showed a significant decrease between the pre-operative and one-year post-operative time points (MFC; p = 0.004, MTP; p = 0.040).
  
  
  CONCLUSIONS
  This study clarified that the fibrocartilage-like repair tissue appeared on the articular surface of the medial compartment after HCO as evidenced by MRI T1ρ and T2 mapping.Cite this article: H. Nishioka, E. Nakamura, J. Hirose, N. Okamoto, S. Yamabe, H. Mizuta. MRI T1ρ and T2 mapping for the assessment of articular cartilage changes in patients with medial knee osteoarthritis after hemicallotasis osteotomy. Bone Joint Res 2016;5:294-300. DOI: 10.1302/2046-3758.57.BJR-2016-0057.R1.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan kinuhnishiok@gmail.com.
authors.forename: H
authors.initials: H
authors.lastname: Nishioka
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Nakamura
authors.affiliation: Department of Medical Information Science and Administration Planning, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Hirose
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Okamoto
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yamabe
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Mizuta
keywords: Cartilage; Hemicallotasis osteotomy; T1ρ mapping; T2 mapping