The Study Of Repairing Bone Defect By Combining Use Of Tissue Engineering Technique And Distraction Osteogenesis

Background:The distraction osteogenesis (DO) technique has been widely applied in the managements of bone defects, limb deformities and fracture non-unions, and has cured many difficult cases. However, the long duration associated with DO treatment and the bone consolidation phase can cause considerable morbidity for the patients, such as pinhole infection, long treatment time, re-fracture, slow consolidation, etc. So many scholars have studied the consolidation phase of distraction osteogenesis, and they have proposed some methods to promote bone consolidation. But these treatments are not always successful and require higher cost and additional procedures/ facilities/equipment, which may not readily available. We proposed a novel method to repair bone defect by combining use of tissue engineering technique and distraction osteogenesis. Through our research, we can investigate the effect of tissue engineering technique on bone consolidation during distraction osteogenesis, and test if combining use of tissue engineering technique and distraction osteogenesis can effectively repair bone defect.Objective:1. Investigate if local injection of platelet-rich plasma can enhance bone consolidation effectively during distraction osteogenesis.2. Test if decalcified bone matrix can promote bone consolidation during distraction osteogenesis.3. Check if decalcified bone matrix combined with platelet-rich plasma can accelerate bone consolidation effectively during distraction osteogenesis.4. Compare the treatment effect of above-mentioned three methods, and discuss which one is more effective. Methods:1. Preparation for the platelet-rich plasma by Landesberg's method with centrifuging two times. Buy DBM.2. Animal model: Osteotomy is made in the middle of left tibia, and 1cm tibia shaft is removed. Fixed with Orthfix unilateral lengthener with 4 pins (2.5cm self-tapping pins). Lengthening begin at day 7 post-operation, at a rate of 1 mm/day, in two steps, for 5 or 10 days. Then the regenerate is allowed to consolidate for further 20 or 25 days. All the animals will be terminated at day 37 following initial surgery.3. Experimental groups: Group A (blanked group): shorten for 1cm and fixation by unilateral lengthener. Group B (DBM group): fill the bone defect with 0.5cm decalcified bone matrix and shorten for 0.5cm. Group C (PRP group): shorten for 1cm and fixation by unilateral lengthener. 500ul platelet-rich plasma are locally injected into distraction gap in day 17 and 27 post-operation. Group D (DBM+PRP group): fill the bone defect with 0.5cm decalcified bone matrix and 1ml platelet-rich plasma and shorten 0.5cm.4. Observation methods: Serial radiographs will be taken at the day of surgery, 5 days during lengthening, end of lengthening, 10 days and 20 days (termination point) post-lengthening, using a C-arm radiography system. The excised bone specimens were scanned by Micro-CT, and then mechanical test.Results:1. Blood platelets count of PRP prepared by Landesberg's method was 876.84±35.26×10~9/L.2. X-ray: The X-ray image of post-op day 37 showed that the regenerate of DBM group and PRP group were significantly better than the blanked group and DBM+PRP group.3. Micro-CT examination: the bone mineral density of DBM group and PRP group are significantly higher than that of the blanked group and DBM+PRP group, especially the PRP group (P<0.05). The statistical difference was not found between the blank group and the DBM+PRP treated group (P >0.05) .4. Mechanical analysis: The maximum torque and torsion stiffness of DBM treated group and PRP treated group were significantly higher than the blank group, especially the PRP treated group (P<0.05). The statistical difference was not found between the blank group and the DBM+PRP group (P >0.05) .Conclusions:1. Blood platelets count of platelet-rich plasma prepared by Landesberg's method was five times of the whole blood group's.2. In the rabbit bone defect/lengthening model, local injection of platelet-rich plasma could enhance bone consolidation effectively during distraction osteogenesis.3. In the normal distraction rate, decalcified bone matrix could promote bone consolidation during distraction osteogenesis compared with blank group.4. Decalcified bone matrix combined with platelet-rich plasma could not promote bone consolidation during distraction osteogenesis compared with blank group.5. According the different effect of the three methods, we could demonstrate that local injection of platelet-rich plasma was more effective to promote bone consolidation during distraction osteogenesis.