The effects of embalming using a 4% formalin solution on the compressive mechanical properties of human cortical bone

Abstract

Background. The use of formalin fixed bone tissue is often avoided because of its assumed influence on the mechanical properties of bone. Fixed bone tissue would minimise biological risks and eliminate preservation issues for long duration experimental tests. This study aimed to determine the short-and long-term effects of embalming, using a solution with 4% formalin concentration, on the mechanical properties of human cortical bone.Methods. Three-millimetre cylindrical specimens of human cortical bone were extracted from two femoral diaphyses and divided in four groups. The first group was used as control, the remaining three groups were left in the embalming solution for 48 h, 4 week, and 8 week, respectively. Compressive mechanical properties, hardness and ash density were assessed. The last was used to check the homogeneity among the four groups.Findings. No significant differences were found among the four groups in yield stress, ultimate stress and hardness. The specimens stored for 8 week in the embalming solution had significant lower Young's modulus (À24%), higher yield strain (+20%) and ultimate strain (+53%) compared to the other groups.Interpretation. On a short-term perspective, embalming did not affect the compressive mechanical properties, nor hardness of human cortical bone, whereas a long-term preservation (8 week) did significantly affect Young's modulus, yield strain and ultimate strain in compression. Preserving bone segments for up to 4 week in an embalming solution with low formalin concentration seems to be an interesting alternative when collecting and/or managing fresh or fresh-frozen bone segments for biomechanical experiments is not possible.

Development and experimental validation of a finite element model of total ankle replacement

“…The main limitation of the model was the use of non-fresh cadaveric bone, which were perfused and conserved 4 years in a formaldehyde solution. This may explain the correlation slope below 1 (Ohman et al, 2008). The validation process was performed only on the anterior side of the tibial surface.…”

Trabecular Fracture Zone Might Not Be the Higher Strain Region of the Trabecular Framework

“…Four femora and four tibiae were obtained from two female cadavers (72 and 78 years old) without skeletal disorders by means of a donor program during the LHDL European project. The samples had been embalmed using the modified Dankmeyer's method (Van Sint Jan and Rooze, 1992;Ohman et al, 2008). Tibiae and femora were cut into slices perpendicular to the longitudinal axis of the bone.…”

Effect of different conservation methods on some mechanical properties of swine bone

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“…van Haaren et al [12] found that the Young's modulus of large bones extracted from goats changes significantly only after one year of storage in formaldehyde. Measurements by Öhman et al [13] show that 8 weeks of storage in formaldehyde does not change the hardness and compressive strength of human cortical bones, but it decreases the Young's modulus measured by compression. Unger et al [9] found that following 6 months of storage of cortical bones removed from human tibia and bovine femur in formaldehyde, the Young's modulus, the flexural strength, and the energy absorption do not change, but the plastic energy absorption is significantly decreased.…”