Preparation and property of nano-hydroxyapatite/polyamide66 composites for ilium-grafting in bone defect following decompression

Yinyin ZHOU; Tao WANG; Jie TAO

ABSTRACT

BACKGROUND:

After excision of vertebra and cervical intervertebral disc, repairs of bone defect after reducing pressure mainly have used titanium mesh and ilium for a long time, but the effect is not perfect.

OBJECTIVE:

To prepare nano-hydroxyapatite/polyamide66 (n-HA/PA66) composites, and to test the representation and biomechanical properties. DESIGN, TIME AND

SETTING:

A repeated and comparative study was performed at Laboratory of Inorganic Material, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics from January to December 2008. MATERIALS Nano-hydroxyapatite crystal was prepared using hydrothermal reaction, and the nano-hydroxyapatite/polyamide66 of bone-grafting specimens was prepared by co-precipitation, cold-pressing and sintering.

METHODS:

Normal C_5 samples were implanted into different materials and then internal-fixed using screw to test the biomechanics. The grouping was as following normal cervical vertebra group, n-HA/PA66 ilium-grafting internal fixation group, and ilium-grafting internal fixation group. Physiological motion of cervical vertebra was simulate to human body at neutral, flexion, extension and lateral-flexion positions. MAIN OUTCOM

MEASURES:

① The phase of the composites was characterized by X-ray diffraction. ② The group of thecomposites was analyzed by infrared spectrum. ③ Scanning electron microscopy was used to analyze the scaffold of bone-grafting specimens. ④ The measurements of biomechanical properties were carried out with normal cervical specimens, bone-grafting specimens and the ilium-grafting specimens.

RESULTS:

① X-ray diffraction results revealed that the main diffraction curves of nano-hydroxyapatite and polyamide66 remained in the composites, but n-HA would widen and weaken the β crystals in polyamide66. ② Infrared spectrum results showed that nano-hydroxyapatite and polyamide66 were mainly linked by hydrogen-bonding. ③ Scanning electron microscopy examined the scaffold of bone-grafting and revealed that the composites had tight combination and good interface. ④ The measurements of biomechanical properties indicated that the bone-grafting specimens had better performances in load-strain, load-displacement and stress intensity in comparison with ilium-grafting ones, only a little bit lower than the normal cervical vertebrae.

CONCLUSION:

The bone-grafting specimens have outstanding biomechanical properties and are an ideal kind of material to instead cervical vertebrae.