Experimental Study Of Bone Morphogenetic Protein-2 In Noncemented Fixation Of Prosthesis

Mechanical loosening has been the most critical and mostly concerned long-term complication. Non-cemented fixation has developed quickly in recent years since widely accepted of the concept of biological fixation. But the capacity of bone growing into bone-prosthesis interface still need to be improved. Because of its osteoinductivity, BMP has attracted many concerns of study. The study on the using of BMP in the interface of artificial joints is rare, and it is also not sure if BMP can improve bone-ingrowth and shear strength at the interface, we studied the method of combining BMP with porous-coated implants, and compared the histological and biomechanical results of 4 types of surface treatment methods by inserting the implants into femur of canine.PurposeHistological, histomorphological analysis and biomechanical test methods were used to analyze the bony ingrowth and shear strength conditions in theinterface of bone and implants of 4 groups. And also tried to find if BMP can enhance the fixation of the implants. We hope that the results of our research can provide the clinical using BMP to improve biological fixation of artificial joint with some theoretical and experimental data.Materials and MethodsWe have inserted 4 types of implants include porous-coated implants(PCA), PCA implants combined with BMP PCA implants coated with hydroxyapatite and HA coated implants into the femur of 12 canines. After 4, 8 and 12 weeks the femur of the canines with the implants were retrieved . Bone ingrowth and shear strength of the interface was studied and analysed by the means of X-ray, soft X-ray, fluorescence tag, non- decalcification ground section, computer-aided image analysis procedure and biomechanical test.Results1. Implants commbined with BMP was observed under stereomicroscope and cobweb-like materials deposited in the pores can be observed. There was obvious differences compared with implants which was not compounded with BMP.2.X-ray, soft X-ray, fluorescence tag, non-decalcification ground section and computer-aided imageanalysis procedure was used in histological study, it shows that the bony ingrowth into interface appeared early than the other groups, so did the maturation of newly formed bone.3. Non- decalcification ground section observation and computer aided image analysis shows the results: the new bone formation ratio of BMP group is 26. 58 ?. 56%, which is much higher than the other groups, and there is significant difference between BMP group and each of the other group statistically.4. Result of biomechanical study using push-out test shows that shear strength of each group appeare to rise with time. Shear strength of BMP group reached a high level at 4 weeks which is 18.94?. UMpa and almost twice of the other group. There is also statistical difference between BMP group and each of the other group.Conclusion1. The method we used in the experiment to combine BMP with porous-coated implants is effective and feasible.2. Porous-coated implants combined with BMP can enhance bony ingrowth at bone-implant interface.3. Porous-coated implants combined with BMP can not only shorten the time of new bone formation and bony ingrowth but also enhance shear strength of bone-implantinterface.4. HA coating is also an effective method of prosthesis surface treatment to improve bone ingrowth and enhance the interface shear strength. But the technique of HA coating is essential factor in processing the prosthesis.