title: Simulation of water content distributions in degenerated human intervertebral discs.
abstract: The objective of this study was to investigate the spatial and temporal variations of water content in intervertebral discs during degeneration and repair processes. We hypothesized that the patterns of water content distribution in the discs are related to the intensity patterns observed in T2-weighted MRI images. Water content distributions in the mildly (e.g., 80% viable cells in the disc, 2.3% decrease in disc height) and moderately (e.g., 40% viable cells in the disc, 9.3% decrease in disc height) degenerated discs were predicted using a finite element model. The variation of water content in the degenerated discs treated with three biological therapies (i.e., increasing the cell density in the nucleus pulposus [Case I], increasing glycosaminoglycan synthesis rate in the nucleus pulposus [Case II], and decreasing glycosaminoglycan degradation rate in the nucleus pulposus [Case III]) were also predicted. It was found that two patterns of water content distributions, a horizontal region with lower water content at the mid-axial plane of nucleus pulposus and a spot with higher water content at the posterior region, were shown during the degeneration progress for the disc simulated in this study. These two patterns disappeared after treatment in Case I, but in Case II and Case III. The implication of these patterns for the horizontal gray band and high intensity zone in T2-weighted MRI images was discussed. This study provided new guidance to develop a novel method for diagnosing disc degeneration and assessing outcomes of biological therapies with MRI techniques. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:147-153, 2017.
authors.affiliation: Department of Biomedical Engineering, University of Miami, 1251 Memorial Drive, MEB206, Coral Gables, 33124-0624 Miami, Florida.
authors.forename: Qiaoqiao
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Miami, Miami, Florida.
authors.forename: Xin
authors.initials: X
authors.lastname: Gao
authors.affiliation: Department of Orthopaedics, University of Miami, Miami, Florida.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Brown
authors.affiliation: Department of Orthopaedic Surgery, NOVA Southeastern University, Fort Lauderdale, Florida.
authors.forename: H Thomas
authors.initials: HT
authors.lastname: Temple
authors.affiliation: Department of Biomedical Engineering, University of Miami, 1251 Memorial Drive, MEB206, Coral Gables, 33124-0624 Miami, Florida.|Department of Mechanical and Aerospace Engineering, University of Miami, Miami, Florida.
authors.forename: Weiyong
authors.initials: W
authors.lastname: Gu
mesh_terms: D018450:Disease Progression; D020342:Finite Element Analysis; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000628:therapy; D008279:Magnetic Resonance Imaging; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water
keywords: biological therapy; disc repair; finite element model; gray band; high intensity zone