Experimental Study On Repairing Extremities Defect With The Nano-Hydroxyapatite/Polyamide Cement

All sorts of extremities defects caused by trauma, infection orresection of a tumour is a difficult problem puzzled plastic surgeons. Itis well known that hydroxyapatite (HA) is a biocompatible material withgood osteoconductivable properties. It has been known that HA canpromote early bone ingrowth. However, this bone substitute ismechanically weak and its particles might migrate from the site of theimplant,on the other hand,the general hydroxyapatite are too brittle to trim .these shortcomings were restricted in clinical for unload-bearing bonerepair The nano-hydroya-patite and polyamide66 (n-HA/PA66) is a newtype of inorganic-organic biomimetic component. Results of the test andanalytical studies indicated that the distribution of n-HA homogeneously inpolyamide matrix, nanograde needle-shape apatite crystals of n-HA wassimilar to bone apatite. A new injectable n-HA/PA66 composite wasinvestigated. The composite has good injectable properties, and can beeasily handled as paste, injecting with a syringe and hardening in situ.. Theinjectable n-HA/PA66 composite cement has a reasonable setting time,high mechanical strength, excellent washout and blood decay resistantproperties.In this experiment,We will study the osteoconductivity ofn-HA/PA66 and the feasibility to repair condyles tibia defect of rabbit withthe n-HA/PA66 composite cement. 【OBJECTIVE】The purpose of this study was to evaluate thebiocompatibility and osteoconductivity of a new bone cement, the cementwas composed mainly of nano-hydroyapatite (n-HA) and polyamide66(PA66);study the ability of repairing condyles tibia defect of rabbit with theinjectable bioactive bone cement ;and study the feasibility use it as theinjectable bone substitute , to provided referenced data for the advanceclinical study. 【METHODS】The animal models of condyles of tibia defect createdwith surgery in the New Zealand white rabbits ,and were injectedn-HA/PA66 cement as the experimental group, injected PMMA and CPC asthe experimental control group. The effect were observed by gross andX-ray and histopathlogical examnation , histological studies wereperformed on thin un-decalcified, In the mean time , the Magneticresonance imagine(MRI) and Biomechanics of new bone were determinedat 2,4,6,8,12W after operation. 【RESULTS】Results of this study showed osteoblastic activity andnew bone formation at the interface between the condyles of tibia defectbone and the cement in the experimental group and CPC group.Nounfavorable reaction was noted in the n-HA/PA66-applied sites .Thebiocompatibility and osteoconductivable properties of n-HA/PA66 cementwere superior to CPC and PMMA, No statistically significant difference wasnoted in the experimental or control sites under the data of biomechanics(P>0.05. 【 CONCLUSIONS 】 Our results show,the nano-hydroxyapatite/Polyamide Composite cement have good biocompatibility and has goodosteoconductivity, and the injectable n-HA/PA66 cement had used torepair condyles of rabbit tibia defect successfully,showed promisingprospect for extremities defect repairing.