Determination of cortical bone porosity and pore size distribution using a low field pulsed NMR approach

Authors

  • Xiaodu Wang,

    Corresponding author
    1. Department of Mechanical Engineering and Biomechanics, College of Engineering, University of Texas at San Antonio, 6900 North Loop, 1604 West, San Antonio, TX 78249, USA
    2. Department of Orthopaedics, University of Texas Health Science, Center at San Antonio, San Antonio, TX 78229, USA
    • Department of Mechanical Engineering and Biomechanics, Engineering Division, University of Texas at San Antonio, 6900 North Loop, 1604 West, San Antonio, TX 78249, USA. Tel.: +1-210-458-5565; fax: +1-210-458-5589
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  • Qingwen Ni

    1. Southwest Research Institute, San Antonio, TX 78228, USA
    Current affiliation:
    1. Department of Physics, Texas A&M International University, 5201 University Boulevard, Laredo, TX 78041, USA
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Abstract

The objective of this study was first to prove the concept of a low field pulsed nuclear magnetic resonance (NMR) process for assessing the cortical porosity and pore size distribution of human bone in vitro, and then to apply the technique to detect age-related changes of bone in these parameters. The Carr-Purcell-Meiboom-Gill NMR spin echo train method is used to determine the porosity, and an inversion NMR spin-spin relaxation (T2) spectrum is used to assess the pore size distribution in cortical bone. Using these techniques, cortical porosity and pore size distribution of 19 specimens of human cadaveric bone, ranging from 16 to 89 years of age, were assessed. The NMR results were compared with the histomorphometric data of the same bone samples to verify the efficacy of the NMR approach. Moreover, a coefficient (surface relaxivity) relating the pore size to the T2 relaxation time was determined empirically for the Haversian canals and the osteocytic lacunae. The results of this study demonstrate that the in vitro NMR approach using T2 relaxation techniques can directly assess the porosity and pore size distribution (Haversian canals and osteocytic lacunae) in human cortical bone. In addition, this study indicates that the age-related changes in cortical porosity relate predominantly to Haversian canals, whereas the porosity of osteocytic lacunae appears to be independent of age.

© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

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