Effect of defatting on the biomechanics of cortical bone

Aijun HUANG; Jianqiang PENG; Qi ZHANG; Weidong ZHAO

ABSTRACT

BACKGROUND:

Defatting is to reduce the special cell surface antigens by clearing fat and lipoprotein, so as to decrease immunological rejection, improve the biocompatibility of allograft bone, and increase osteogenic potential. However, the effect of defatting on biomechanical performance of bone remains controversial.

OBJECTIVE:

To explore the influence of defatting on the biomechanics of bovine cortical bone samples.DESIGN, TIME AND

SETTING:

Randomized, self-controlled observation was performed in Futian People's Hospital of Guangdong Medical College between 2006 and 2008.MATERIALS Eight pairs of healthy adult bovine femora were used. Bone blocks, 50 mm long and 10 mm wide, were selected from each pair of femora, and burnished into 24 pairs of 7 mm×7 mm×40 mm rectangular bovine cortical bone samples.

METHODS:

The 24 pairs of cortical bone samples were randomly divided into two groups (n=12). One of each pair was selected as test group sample, and the other as control group sample. The samples of test group were defatted In 500 mL chloroform and methanol mixture (11) for 24 hours, while control samples were immerged in deionized water for 24 hours. Six samples from each group were selected for axial compressive test and three-point bending test.MAIN OUTCOME

MEASURES:

Load and deflection of every sample.

RESULTS:

Axial compressive test showed that the maximum load and the maximum strain of defatted samples were significantly decreased compared with control group, but the fragility and elastic modulus were increased (P < 0.05). In three-point bending test, the maximum load and the maximum stress of defatted sampled were significantly decreased, the maximum deflection was decreased, and the elastic modulus was increased (P < 0.05).

CONCLUSION:

The mechanical strength of cortical bone decreased but the fragility increased after defatting.