Vet Comp Orthop Traumatol 2000; 13(02): 59-64 DOI: 10.1055/s-0038-1632632
Original Research
Schattauer GmbH
The Effect of Repeated Freeze-thaw Cycles on the Biomechanical Properties of Canine Cortical Bone
C. P. Boutros
2
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
,
D. R. Trout
2
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
,
M. Kasra
1
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
,
M. D. Grynpas
1
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
› InstitutsangabenThis study was supported by grants from Pet Trust, Ontario Veterinary College, University of Guelph. The authors thank Ms. Anne Valliant for assistance with statistical analysis.
As orthopaedic investigations have become more intricate, bone specimens have sometimes undergone multiple freeze-thaw cycles prior to biomechanical testing. The purpose of this study was to determine if repeated freezing and thawing affected the mechanical properties of canine cortical bone. Six pairs of third-metacarpal bones were tested in three-point bending and six pairs of femurs were tested in torsion. At the time of collection, one member of each pair was tested destructively. The other member was tested nondestructively at the time of collection and after each of five freeze-thaw cycles, followed by destructive testing after the fifth cycle. For destructive tests, the material properties (modulus, maximum stress, maximum strain and absorbed energy) of a specimen at the time of collection were compared to those of the corresponding contralateral specimen that had undergone five freeze-thaw cycles. For repeated nondestructive tests, the modulus of a specimen at the time of collection was compared to modulus of the same specimen at each of the five thaw intervals. During destructive testing, there was a significant (p = 0.02) decrease (20%) in maximum torsional strain. Other changes in bending and torsional destructive properties were not statistically significant. During repeated nondestructive testing, there were solitary significant (p < 0.05) increases (8% and 9%, respectively) in both bending and torsional modulus. However, these isolated changes were not correlated to the number of freeze-thaw cycles. The pattern of alterations in destructive and non-destructive biomechanical properties was most consistent with varying specimen dehydration at each thaw interval. Despite using accepted methods to maintain specimen hydration, repeated freezing, thawing, handling and testing of cortical bone increased the risk of moisture loss. Unless stringent efforts are made to ensure proper hydration, the mechanical properties of canine cortical bone will be altered by repeated freezing and thawing, affecting the results of studies utilizing this technique.
The effect of five freeze-thaw cycles on paired canine cortical bone specimens was evaluated using destructive and repeated non-destructive three-point bending and torsion tests. A significant decrease in destructive torsional strain and isolated significant increases in nondestructive bending and torsional modulus were most consistent with varying specimen dehydration at each thaw interval.
Keywords
Biomechanical testing -
cortical bone -
repeated freezing -
dog
REFERENCES
1
An YH,
Kang Q,
Friedman RJ.
Mechanical symmetry of rabbit bones studied by bending and indentation testing. Am J Vet Res 1996; 57: 1786-9.
2
Borchers RE,
Gibson LJ,
Burchardt H.
et al. Effects of selected thermal variables on the mechanical properties of trabecular bone. Biomaterials (England) 1995; 16: 545-51.
6
Griffon DJ,
Wallace LJ,
Bechtold JE.
Biomechanical properties of canine corticocancellous bone frozen in normal saline solution. Am J Vet Res 1995; 56: 822-5.
7
Hus BT,
Anderson MA,
Wagner-Mann CC.
et al. Effects of temperature and storage time on pin pull-out testing in harvested canine femurs. Am J Vet Res 1995; 56: 715-9.
8
Johnson AL,
Moutray M,
Hoffman WE.
Effect of ethylene oxide sterilization and storage conditions on canine cortical bone harvested for banking. Vet Surg 1987; 16: 418-22.
9
Kang Q,
An YH,
Friedman RJ.
Effect of multiple freezing-thawing cycles on the ultimate indentation load and stiffness of bovine cancellous bone. Am J Vet Res 1997; 58: 1171-3.
14
McCalden RW,
McGeough JA,
Court-Brown CM.
Age-related changes in the compressive strength of cancellous bone. The relative importance of changes in density and trabecular architecture. J Bone Joint Surg 1997; 79A: 421-7.
17
Pelker RR,
Friedlaender GE,
Markham TC.
et al. Effects of freezing and freeze-drying on the biomechanical properties of rat bone. J Orthop Res 1984; 01: 405-11.
18
Roe SC,
Pijanowski GJ,
Johnson AL.
Biomechanical properties of canine cortical bone allografts: effects of preparation and storage. Am J Vet Res 1988; 49: 873-7.
19
Schulz KS,
Waldron DR,
Grant JW.
et al. Biomechanics of the thoracolumbar vertebral column of dogs during lateral bending. Am J Vet Res 1996; 57: 1228-32.
21
Steel RGD,
Torrie JH.
Comparisons involving two sample means. In: Principles and Proced u res of Statistics. A Biomedical Approach. 2nd ed. Toronto: McGraw-Hill Book Co; 1980: 86-121.
25
Trostle SS,
Wilson DG,
Dueland RT.
et al. In vitro biomechanical comparison of solid and tubular interlocking nails in neonatal bovine femurs. Vet Surg 1995; 24: 235-43.
26
Tshamala M,
van Bree H,
Mattheeuws D.
Biomechanical properties of ethylene oxide sterilized and cryopreserved cortical bone allografts. Vet Comp Orthop Traumatol 1994; 07: 25-30.
