title: Partial removal of pore and loosely bound water by low-energy drying decreases cortical bone toughness in young and old donors.
abstract: With an ability to quantify matrix-bound and pore water in bone, (1)H nuclear magnetic resonance (NMR) relaxometry can potentially be implemented in clinical imaging to assess the fracture resistance of bone in a way that is independent of current X-ray techniques, which assess bone mineral density as a correlate of bone strength. Working towards that goal, we quantified the effect of partial dehydration in air on the mechanical and NMR properties of human cortical bone in order to understand whether NMR is sensitive to water-bone interactions at low energy and whether such interactions contribute to the age-related difference in the toughness of bone. Cadaveric femurs were collected from male and female donors falling into two age groups: 21-60 years of age (young) and 74-99 years of age (old). After extracting two samples from the medial cortex of the mid-shaft, tensile tests were conducted on Wet specimens and paired, Partially Dry (PtlD) specimens (prepared by low-energy drying in air to remove ∼3% of original mass before testing). Prior analysis by micro-computed tomography found that there were no differences in intra-cortical porosity between the Wet and PtlD specimens nor did an age-related difference in porosity exist. PtlD specimens from young and old donors had significantly less toughness than Wet specimens, primarily due to a dehydration-related decrease in post-yield strain. The low-energy drying protocol did not affect the modulus and yield strength of bone. Subsequent dehydration of the PtlD specimens in a vacuum oven at 62°C and then 103°C, with quantification of water loss at each temperature, revealed an age-related shift from more loosely bound water to more tightly bound water. NMR detected a change in both bound and pore water pools with low-energy air-drying, and both pools were effectively removed when bone was oven-dried at 62°C, irrespective of donor age. Although not strictly significant due to variability in the drying and testing conditions, the absolute difference in toughness between Wet and PtlD tended to be greater for the younger donors that had higher bone toughness and more bound water for the wet condition than did the older donors. With sensitivity to low-energy bone-water interactions, NMR, which underpins magnetic resonance imaging, has potential to assess fracture resistance of bone as it relates to bone toughness.
authors: Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN 27212, USA. jeffry.s.nyman@vanderbilt.edu
authors: Jeffry S
authors: JS
authors: Nyman
authors: Lacey E
authors: LE
authors: Gorochow
authors: R
authors: R
authors: Adam Horch
authors: Sasidhar
authors: S
authors: Uppuganti
authors: Ahbid
authors: A
authors: Zein-Sabatto
authors: Mary Katherine
authors: MK
authors: Manhard
authors: Mark D
authors: MD
authors: Does
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001696:Biomechanical Phenomena; D002102:Cadaver; D003890:Desiccation; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000502:physiology*; D050723:Fractures, Bone / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D008297:Male; D055595:Mechanical Phenomena; D008875:Middle Aged; D016062:Porosity; D013696:Temperature; D013718:Tensile Strength; D014867:Water / Q000737:chemistry; D055114:X-Ray Microtomography; D055815:Young Adult
chemical_list: D014867:Water
references: PLoS One. 2011 Jan 21;6(1):e16359
references: 21283693
references: Calcif Tissue Res. 1977 May 31;23(1):1-5
references: 890540
references: Magn Reson Med. 2012 Dec;68(6):1774-84
references: 22294340
references: Connect Tissue Res. 1987;16(4):281-303
references: 3451846
references: Ann Rheum Dis. 2005 Feb;64(2):222-5
references: 15647430
references: Calcif Tissue Int. 1986 Oct;39(4):291-2
references: 3098392
references: Magn Reson Med. 2010 Dec;64(6):1652-7
references: 20665825
references: Structure. 1995 Sep 15;3(9):893-906
references: 8535783
references: J Bone Miner Res. 2005 Apr;20(4):625-34
references: 15765182
references: J Biomech Eng. 1993 Nov;115(4A):447-9
references: 8309241
references: Connect Tissue Res. 1996;33(4):275-82
references: 8834445
references: Calcif Tissue Res. 1978 Dec 8;26(2):111-8
references: 737557
references: Biopolymers. 1978 Dec;17(12):2799-2815
references: 728548
references: Acta Orthop Scand. 1966;37(1):29-48
references: 5940056
references: Magn Reson Med. 2010 Sep;64(3):680-7
references: 20806375
references: J Mol Biol. 1985 Jan 20;181(2):265-70
references: 3981637
references: Calcif Tissue Int. 2004 Oct;75(4):321-8
references: 15549647
references: J Orthop Res. 2003 Mar;21(2):312-9
references: 12568964
references: J Biomech. 2006;39(5):931-8
references: 16488231
references: Biophys J. 2006 May 15;90(10):3722-31
references: 16500963
references: J Biomech. 2003 Feb;36(2):229-37
references: 12547360
references: Arch Orthop Trauma Surg. 1985;104(2):89-93
references: 4051703
references: J Biomech. 2008;41(9):1929-36
references: 18502430
references: Connect Tissue Res. 1992;28(4):263-87
references: 1304442
references: Biopolymers. 1992 Feb;32(2):189-95
references: 1637993
references: Bone. 2010 Dec;47(6):1048-53
references: 20736094
references: J Am Chem Soc. 2009 Dec 2;131(47):17064-5
references: 19894735
references: J Gen Physiol. 1925 Sep 20;9(1):63-71
references: 19872232
references: Bone. 2002 Jul;31(1):1-7
references: 12110404
references: J Mol Biol. 2005 Feb 18;346(2):551-6
references: 15670603
references: Matrix. 1989;9(6):443-50
references: 2635757
references: Bone. 2010 May;46(5):1391-9
references: 20096815
references: Am J Anat. 1952 Nov;91(3):331-62
references: 12996443
references: J Comput Chem. 2010 Mar;31(4):764-77
references: 19569200
references: J Bone Joint Surg Am. 1993 Aug;75(8):1193-205
references: 8354678
references: J Biomed Mater Res. 2002;63(1):31-6
references: 11787026
references: Colloids Surf B Biointerfaces. 2006 Mar 15;48(2):167-75
references: 16531020
references: J Bone Miner Res. 2012 Apr;27(4):848-57
references: 22190232
references: Biopolymers. 1974 Dec;13(12):2489-2503
references: 4441607
references: Clin Orthop Relat Res. 1975 Oct;(112):263-315
references: 1192643
references: J Appl Physiol. 1951 Mar;3(9):563-72
references: 14824039
references: J Bone Miner Res. 2010 May;25(5):983-93
references: 19888900
references: Biopolymers. 1977 Feb;16(2):231-46
references: 831859
references: J Orthop Res. 2007 May;25(5):646-55
references: 17266142
references: J Bone Joint Surg Am. 1966 Jan;48(1):140-8
references: 5902798
references: Bone. 2008 Jan;42(1):193-9
references: 17964874