THE EFFECTS OF EMBALMING ON THE COMPRESSIVE MECHANICAL PROPERTIES OF HUMAN CORTICAL BONE.pdf

Bone and Dental

Short Talk ST-19

S337

THE EFFECTS OF EMBALMING ON THE COMPRESSIVE

MECHANICAL PROPERTIES OF HUMAN CORTICAL BONE

Caroline Öhman (1), Enrico Dall’Ara (1), Massimiliano Baleani (1),

Serge Vant Sint Jan (2), Marco Viceconti(1)

1. Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Bologna, Italy

2. Université Libre de Bruxelles, Brussels, Belgium

Introduction

The use of formalin fixed bone tissue for

experimental biomechanics would minimize

biological risks and make sample management

easier. However this fixation technique has often

been avoided because of its assumed effect on the

mechanical properties of bones. The aim of the

present study was to determine the short- and long-

term effect of a solution with a low formalin

concentration (4%) on the compressive mechanical

properties of cortical bone.

Furthermore, hardness (HV) and ash density ( )

were assessed.

An analysis of variance (ANOVA) and a post-hoc

(Scheffe’s) were used for statistical analyses.

Results

The results for the four groups are summarised in

Table 1.

A significant difference in Young’s modulus was

found between Group 1 and 4 (P<0.014), Group 2

and 4 (P<0.040), and Group 3 and 4 (P<0.045).

Whereas no significant differences in, ultimate

stress, ash density and hardness were found among

the four groups (ANOVA P=0.83, P=0.63 and

P=0.06, respectively).

Methods

64 cylindrical specimens (3 mm in diameter and 20

mm in height) of human cortical bone were

extracted from two human femoral diaphyses and

divided randomly in four groups (16

specimens/group). The first group was used as a

control group (G1), the remaining three groups

were left in an embalming solution for 48 hours

(G2), 4 weeks (G3), and 8 weeks (G4),

respectively. The embalming fluid used in this

study was the modified Dankmeyer’s method, a 4%

formalin embalming solution [Van Sint Jan, 1992].

The specimens were left in Ringer’s solution at

room temperature for 24 hours before testing to

ensure the hydration of the bone tissue.

Compressive testing (see Figure 1) of the

specimens was performed to determine the

compressive Young’s modulus (E) and ultimate

strength (US).

E(GPa) US(MPa)

(mg/mm 3 )

16±3

162±31

1.11±0.08

44±5

16 ±4

157±29

1.09±0.10

44±4

16±5

163±25

1.15±0.07

44±4

12±3

157±16

1.09±0.08

45±6

Table 1: Young’s modulus, ultimate strength, ash

density and hardness results of the four groups.

Discussion

Formalin fixation did not affect the elastic modulus,

the ultimate stress and the hardness of human

cortical bone on a short-term perspective, whereas

long-term preservation (8 weeks) did have a

significant effect on the elastic properties. A low

concentration formalin solution seems to be an

interesting method to preserve bone segment when

it is not possible to collect and/or to manage fresh

or thawed bone segment for biomechanical

experiments.

References

Van Sint Jan et al , Surg Radiol Anat, 14: 325-9,

1992.

Acknowledements

This work was partially supported by the European

Community (project number: IST-2004-026932;

project title: Living Human Digital Library;

acronym: LHDL).

Figure 1: Set-up of the mechanical test.

16th ESB Congress, Short Talks, Tuesday 8 July 2008

Journal of Biomechanics 41(S1)

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