| Objective On the basis of scientific experimental data obtained, we evaluate the physical characteristic of the bone cement, Prolene net with bone cement "sandwich" artificial composite materials. We also evaluate adjacent tissue thermal damage of bone cement induced by the exothermic reaction in the process of repair and reconstruction of the chest wall, and actively explore the prevention from the thermal damage.Methods 1. The compressive strength test: According to the clinical application of artificial materials, the experiment was divided into three groups, namely pig biological rib group, bone cement rib group, prolene net with bone cement “sandwich” composite rib group. The groups were subjected to compressive strength tests. 2. To evaluate exothermic reaction damage of the bone cement for the tissue of experimental animal, and evaluate the effect of hypothermic normal saline perfusion on preventing thermal injury. According to the experimental purpose, 4 mongrel dogs were randomly divided into thermal injury group and perfusion thermal injury protection group, after thoracotomy. In the chest wall and bilateral ribs of the dogs, a artificial large chest wall defect model at the size of 12cm×6cm was made. Two pieces of 15cm×15cm prolene nets with 60 g bone cement in the "sandwich" method was used for the repair and reconstruction for the chest wall defect of experimental dogs. The thickness of bone cement prosthesis chest wall was 10 mm. In the thermal injury group, the dogs didn’t not accept any heat injury prevention measures To prevent the thermal damageof adjacent tissues induced by exothermic reaction in the process of moulding one cement, we constructed normal saline perfusion circulation system, in which we utilized 25℃ normal saline continuous perfusion circulation at a speed of 500 ml per minute to match the cooling effect. Finally, muscle tissue samples of the thermal damage group and thermal damage protection group were stained with HE and phosphotungstic acid haematoxylin. The heat shock protein 70 was also detected by immunohistochemistry and transmission electron microscopic. 3. Statistical analysis. The data were analyzed by SPSS 18.0 statistical software. The measurement data in the experiment was expressed with Mean± SD( sx ±). And the results between the experimental groups were compared using student’s t test. α=0.05(two-tailed) as inspection standard, P < 0.05 was considered statistically significant.Results 1. The comparation of main physics characteristic of biological rib, bone cement rib andprolene net with bone cement “sandwich” composite rib We accurately determinated the compressive strength of the three kinds of materials, and found that average compressive strength of biological rib was 429.06N(429.06±55.58N), bone cement rib was 543.91N(543.91±174.06N), and prolene net with bone cement “sandwich” composite rib was 522.81N(522.81±129.87N). The flexility of biological rib was better than bone cement rib and prolene net with bone cement “sandwich” composite rib. The compressive strength of bone cement rib was the highest among three materials, the prolene net with bone cement “sandwich” composite rib was second, and biological rib was the last(P<0.05). However, we found that there was no notable difference between bone cement rib and the prolene net with bone cement “sandwich” composite rib.2.Pathological change of adjacent tissue induced by exothermic reaction of the bone cement in experimental dogs in vivo and the effect of perfusion of hypothermia saline on the prevention of thermal damage The maximum temperature induced by chemical exothermic reaction of bone cement sternal prosthesis in the thermal damage group during the process of animal experiments was 89℃, and the temperature above 45℃ was sustained for 12 minutes; However, the temperature at the junction of bone cement sternal prosthesis and adjacent tissues and organs was kept between 23~36℃ in the perfusion of hypothermia normal saline thermal damage protection group, and the effect of cooling measure was satisfied. We compared the muscle tissue samples of the thermal damage group and thermal damage protection group through HE staining, phosphotungstic acid haematoxylin staining, heat shock protein 70 immunohistochemical examination and transmission electron microscopic observation. The results showed that tissues adjacent to bone cement suffered severe thermal damage and histopathologic and microstructure changed obviously in the thermal damage group, while tissues in the thermal damage protection group did not.Conclusion 1.The compressive strength of bone cement rib and prolene net with bone cement “sandwich” composite rib was much more higher than that of biological rib, and bone cement was an excellent artificial material for repairing and reconstructiing large chest wall defect. 2.The flexility of biological rib was better than bone cement rib and prolene net with bone cement “sandwich” composite rib. 3.There was no statistical significance compared prolene net with bone cement “sandwich” composite rib and bone cement at the compressive strength, but the physical property of the former was better than the latter. So we proposed to use prolene net with bone cement “sandwich”composite rib for clinical repair and reconstruction of large chest wall defect. 4.The exothermic reaction of bone cement was swift and violent in the process of moulding bone cement. The maximum temperature was 89℃, and the temperature above 45 ℃ would last for 12 minutes, and the higher temperature could cause pathological thermal damage to adjacent tissues. 5.The continuous perfusion circulation of 25℃ hypothermia normal saline at a speed of 500 ml per minute could ensure that the temperature at the junction of bone cement sternal prosthesis and adjacent tissues or/and organs was maintained between 23-36℃. Although it was slightly higher than the ideal safe temperature, the effect of cooling measure was satisfied, which couldn’t lead to pathological thermal damage of adjacent tissues caused by exothermic reaction of bone cement in vivo. |
PDF Full Text Request