Observational Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Apr 18, 2017; 8(4): 350-356
Published online Apr 18, 2017. doi: 10.5312/wjo.v8.i4.350
T1ρ/T2 mapping and histopathology of degenerative cartilage in advanced knee osteoarthritis
Benjamin S Kester, Philip M Carpenter, Hon J Yu, Taiki Nozaki, Yasuhito Kaneko, Hiroshi Yoshioka, Ran Schwarzkopf
Benjamin S Kester, Ran Schwarzkopf, Division of Adult Reconstruction, Department of Orthopaedics, NYU Langone Medical Center Hospital for Joint Diseases, New York, NY 10003, United States
Philip M Carpenter, Department of Pathology, University of California Irvine, Orange, CA 92868, United States
Hon J Yu, Taiki Nozaki, Yasuhito Kaneko, Hiroshi Yoshioka, Department of Radiological Sciences, University of California Irvine, Orange, CA 92868, United States
Author contributions: All authors participated in the interpretation of data, revision and final approval of the manuscript; Kester BS interpreted the data, drafted and completed the manuscript; Carpenter PM additionally carried out the histologic analysis; Yu HJ, Nozaki T, Kaneko Y and Yoshioka H equally participated in the study design, radiographic interpretation, and statistical analysis; Yoshioka H and Schwarzkopf R were the principle investigators, lead of study conception and guided manuscript completion.
Supported by The National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, No. UL1 TR000153. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Institutional review board statement: The study protocol was approved by the University of California Irvine institutional review board.
Informed consent statement: All subjects provided written informed consent before any study-related procedures were performed.
Conflict-of-interest statement: To the best of our knowledge, no conflict of interest exists.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Benjamin S Kester, MD, Division of Adult Reconstruction, Department of Orthopaedics, NYU Langone Medical Center Hospital for Joint Diseases, 301 E 17th St, New York, NY 10003, United States. benjamin.kester@nyumc.org
Telephone: +1-212-5986000
Received: October 10, 2016
Peer-review started: October 11, 2016
First decision: November 30, 2016
Revised: December 13, 2016
Accepted: January 2, 2017
Article in press: January 3, 2017
Published online: April 18, 2017
Abstract
AIM

To investigate whether normal thickness cartilage in osteoarthritic knees demonstrate depletion of proteoglycan or collagen content compared to healthy knees.

METHODS

Magnetic resonance (MR) images were acquired from 5 subjects scheduled for total knee arthroplasty (TKA) (mean age 70 years) and 20 young healthy control subjects without knee pain (mean age 28.9 years). MR images of T1ρ mapping, T2 mapping, and fat suppressed proton-density weighted sequences were obtained. Following TKA each condyle was divided into 4 parts (distal medial, posterior medial, distal lateral, posterior lateral) for cartilage analysis. Twenty specimens (bone and cartilage blocks) were examined. For each joint, the degree and extent of cartilage destruction was determined using the Osteoarthritis Research Society International cartilage histopathology assessment system. In magnetic resonance imaging (MRI) analysis, 2 readers performed cartilage segmentation for T1ρ/T2 values and cartilage thickness measurement.

RESULTS

Eleven areas in MRI including normal or near normal cartilage thickness were selected. The corresponding histopathological sections demonstrated mild to moderate osteoarthritis (OA). There was no significant difference in cartilage thickness in MRI between control and advanced OA samples [medial distal condyle, P = 0.461; medial posterior condyle (MPC), P = 0.352; lateral distal condyle, P = 0.654; lateral posterior condyle, P = 0.550], suggesting arthritic specimens were morphologically similar to normal or early staged degenerative cartilage. Cartilage T2 and T1ρ values from the MPC were significantly higher among the patients with advanced OA (P = 0.043). For remaining condylar samples there was no statistical difference in T2 and T1ρ values between cases and controls but there was a trend towards higher values in advanced OA patients.

CONCLUSION

Though cartilage is morphologically normal or near normal, degenerative changes exist in advanced OA patients. These changes can be detected with T2 and T1ρ MRI techniques.

Keywords: T1rho, Osteoarthritis, Magnetic resonance imaging, Cartilage, Knee

Core tip: Magnetic resonance images of eleven healthy knees and five knees with advanced osteoarthritis (OA) were studied using T1ρ and T2 mapping. Histopathologic samples were also taken from the five osteoarthritic knees following total knee arthroplasty. Our results indicate that even though cartilage is morphologically normal or near normal, cartilage degenerative changes exist in advanced OA patients. This suggests that normal thickness cartilage or mild cartilage thinning in the advanced OA knee demonstrates depletion of proteoglycan or collagen content compared with similar appearing cartilage in young healthy knees. These early changes can be detected with T2 and T1ρ MRI techniques.