| Objective: The bone formation is a complicated process with many kinds of cells and mutiple factor participating. The osteoblasts recruit and duplicate, and get deeply differentiated which rusults in the new bone formation through the accumulation and mineralization of the extracellular matrix. This process is influenced by many factors. In China, the population aging has been become a social ploblem. For old men, the osteoporosis inducing fractures would be increased. How to prevent and cure osteoporosis and promote bone formation is a ploblem to be solved which possesses big clinical significance. It is known that bone marrow plays an important role in the process of bone formation. It's helpful in evaluating in vivo bone formation and resorption in a relatively short time span. Some reseachers have reported the osteogenesis is enhanced following marrow ablation. According to this theory, we designed this experiment to observe and approach the bone generation changing preliminarily after marrow ablation through observing of X-ray mean gray values and biomechanics parameters. The objective of our study is to forsee the operation method for curing and preventing osteoporosis. Methods: We empolyed thirty-six famale Sprague Dawley rats, each weighing approximately 300g. They were divided into two groups of eighteen each in random. The two groups are normal saline irigating group(NS group) and VitD3 irigating group(VD group). Animals were anesthetized with ketamine(100mg/kg) by intraperitoneal injection. A 1.0cm incision was made over the knee joint and the intracondylar notch was exposed under sterile operation. The intracondylar notch was opened by drilling following the marrow cavity in use of 1.0mm diameter Kirschner wire. The left lower extremity of NS group animals is experimental group side(EG side) and subjected to bone marrow ablation by normal saline flushing. The opposite side is sham experimental group side(sham side) in which an access hole was drilled in the femoral intracondylar contex without removal of the bone marrow. Then the incision was closed in full-thickness. The left lower extremity of VD group animals is experimental group side(EG side), in which the marrow cavity is flushed by VitD3. The marrow ablation of the right side is in use of the normal saline and indicated as control group side(CG side). The eighteen animals of group then divided into three subgroups in random, six each. The animals of these subgroups were sacrificed on sequential week 1, 2 and 3, and then subjected to the same experimental methods as follow. The X-ray images were shot in the same condition setting. Get the MGVs data after analyzing the images in use of Photoshop7.0(ADOBE Inc., USA). Because of the unavoidable error, we correct the MGVs according to the gray values of the letter on the X-ray image. After the radiography experiment, the whole femoral from the rats were surgically removed and soft tissue was dissected free from the hard tissue. And then divided into two group (three each) subjected to the torsion test and three-point bending test on the mechanics testing apparatus. The maximum torque and bending load were recorded. The statistical analysis was performed using SPSS 13.0 and the conclusion was made.Results: All the animals got normal treatment after being conscious from anaesthesia. All thirty six rats lived to the expected time. The results of the MGVs datum showed that at week one, the EG side of the NS group rats had significant difference from the Sham side(P<0.05). At week two, there was no statistical difference(P>0.05). At week four after operation, the datum were 128.31+2.70, 137.72+3.06 respectively. After calculating , the value of P is 0.007, there is a statistical difference; The EG side of the VD group rats compared to the CG sides at week one, two and three, there was no significant statistical difference.We performed biomechanics test on the subgrouped rats and the statistical analysis was made. The results of the three-point bending test showed that at week one and two, there was no statistical difference between the maximum load of the EG side and Sham side(P>0.05). At week three, the datum was 110.49+1.01, 93.26+3.78, and the value of P is 0.038. There was a statistical difference(P<0.05); In the intortion test, there was no difference among the maximum torque at week one, two, three. In VD group the values of P are 0.886, 0.343, 0.098 respectively. There were no statistical difference(P>0.05); In the intortion test, there was no significant difference between NS group and VD group after statitical analysis.Conclusion: Marrow ablation has positive effects on bone formation, and enhancing the osteogenesis. So we can foresee the clinical meaning of marrow ablation, providing the theory evidence of osteoporosis treatment and prevention by operating method; Compared to the ablation by normal saline, VitD3 irigating presented no significant difference. The choice of the irrigating drugs for further promoting bone formation needs to be researced.. |
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