| The treatment of bone defection is one of the most important subjects in orthopaedics. Because traditional methods such as autografting and allografting have some shortcomings, people have been searching the bone substitutes. In this study, using rhBMP-2 as bone growth factor, the filling type of bioactive bone substitute and the large segmental bioactive bone substitute were made. And then, a series of animal experiments were done to test the bone forming activity and the bone defect repairing ability of these two types of bone substitutes, so as to provide some theoretical basis for them using in the future.I The preparation of the filling type of bioactive bone substitutesand related research1 The experimental research of rhBMP-2 in inducing ectopic bone formation Objective: To test the activity of rhBMP-2 in this study in inducing ectopic bone formation, and to understand its activity when it compounding with the carrier. Methods: Three materials were implanted into mice's thigh muscle pouches, which are gelatin, rhBMP-2 and the composite of rhBMP-2 and gelatin. The effect of ectopic bone formation was evaluated by radiography and histology in 3 days, 1week, 2 and 3 weeks after operation, and the weight of new bone inducing by a unit rhBMP-2 was calculated in 3 weeks of postoperation to compare the activity of bone formation. Results: There was new bone formed in the rhBMP-2 group and the composite group in 2-3 weeks of postoperation, but in the control group there was only inflammatory reaction. The weight of new bone induced by a unit dose of rhBMP-2 in 3 weeks of postoperation in composite group is 8.8 times of that in rhBMP-2 group. Conclusions: The rhBMP-2 has a very good activity in inducing ectopic bone formation; the gelatin as a carrier could amplify the activity about 8.8 times.2 The preparation of three filling type of bioactive bone substitutes and the experimental study using them to repair defects in long bone of the rabbitsObjective: Combining gelatin ?hydroxyapatite (Gel ?HA) with rhBMP-2, lecithin with rhBMP-2, and chitin with rhBMP-2 to prepare three filling type of bioactive bone substitutes; to observe their repairing ability to bone defect, and to compare the effect of carriers to the bone forming ability of rhBMP-2. Methods: A 1.5 cm defect was made in middle-superior segment of rabbit's radius, then the three substitutes were implanted into the defect as three experiment groups, and nothing was implanted in the fourth group which is a control group. The repairing effect was evaluated by radiograph in 4, 8 and 12 weeks of postoperation, and by histology and BMD (Bone Mineral Density) in 12 weeks of postoperation. Results: Radiographically, in the rhBMP-2/Gel ?HA and rhBMP-2/Lec groups, all defects were connected by callus in 12 weeks; in the rhBMP-2/Chi group, there formed a soft tissue mass, and the defect was not repaired; in the control group, there was no callus formation and the defect was not repaired. Histologically, in the rhBMP-2/Gel ?HA and the rhBMP-2/Lec groups, the defects were connected by callus, which was composed by outer's lamellar bone and center's myeloid tissue;the soft tissue in the defect site in rhBMP-2/Chi group was a inflammation mass wrapped by fibrous tissue; in the control group, the defect was connected by fibrous tissue. The BMD of the new callus in the rhBMP-2/Gel ?HA group and the rhBMP-2/Lec group were 55.5% and 48.1% of that of the normal radius in 12 weeks of postoperation. About degradation time, the lecithin is about 1 week, and the Gel ?HA is about 2 weeks. Conclusions: The rhBMP-2 has positive activity of inducing bone formation. Lecithin and Gel ?HA are good carriers of the rhBMP-2, and relatively, Gel ?HA has a better slowly-releasing effect. Chitin in this experiment is not suitable to be a carrier of rhBMP-2 for its foreign body reaction in the rabbit. 3 The preparation of a filling type of bioactive bone substitutes and the experimental study using them to repair defects in long bone of the dogsObjectiv...
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