Experimental Study On Prevention Adhesion After Orbital Blowout Fracture Repaired By Man-made Plates Of Amniotic Membrane

Objective: To approach the effect of preventing adhesion after the orbital blowout fracture on the orbit tissue by the amniotic membrane , and observe whether the amniotic membrane had impact on the optic nerve.Methods: Twenty six mature New Zealand white rabbits, of which 10 were divided into one week group after the surgery, and another 10 were divided into one month group after surgery. Own control method was used , left eye in the experimental group and right eye in the control group. The remaining 6 were for the blank control group. Through breaking the lacrimal bone of rabbits in the top of the orbit and caused the 1.2cm×1.2cm-sized bone defect, at the same time, its corresponding orbital soft tissue should be damaged, then the animal models of the orbital fracture were established and postoperative results could be evaluated by CT imaging. The experimental group by implanting plates of the amniotic membrane were repaird, and the control group were directly implanted HA plates to repair, no treatment for the blank group. The animals were killed after one week and one month, through observation of eye-adhesion, pathology score, components of collagen fibers by polarized light, immunohistochemical staining of transforming growth factor (TGF-β), and methods of image analysis of the average optical density, light area, integral optical density, we analyzed the statistical differences among these three groups, and ultimately evaluated this method. We judged the adhesion score and the grade of inflammatory response by the number of samples non-parametric rank sum test (Kruskal-Wallis Test). For immunohistochemical analysis of the images we used single-factor analysis of variance and SNK-q test. We thought it meant significantly when P <0.05.Results: 1 General Observation 1.1 One week after the implanting, the classification score of degree of adhesion results in the control group four point there were five, three had three point, two point there were two ;in experimental group four point there were three, four had three point, there were three 2-point ; in blank group four points there was only one, one had three point, there were four 2-point,and only one eye was one point. Statistics showed that the difference of adhesion grade between the experimental group and the control group was not significant (p> 0.05). The difference of classification adhesion between the blank group and the experimental group and the control group was significance (p <0.05).1.2 One month after implanting, the classification score of degree of adhesion results in the control group four point there were three, five had three point, two point there were two ;in experimental group four point there was one, three had three point, there were four 2-point ,and two 1-point; in blank group two had three point, there were three 2-point,and only one eye was one point. Statistics showed that the difference of classification adhesion between the blank group and the experimental group was significance (p <0.05). The difference of adhesion grade between the experimental group and the blank group was not significant (p> 0.05).2 Histopathological Examination:2.1 One week after the implanting, the results of inflammation score in the control group there were five eyes of three point, four of two point, one of one point; in the experimental group there were four eyes of three point, three of two point, two of one point; in the blank group there were one eye of three point, two of two point, two of one point. Statistics showed that the difference fo inflammatory response between experimental group and control group was not significant (p> 0.05),and the difference between the blank group and the experimental group and the control group was significant (p <0.05).2.2 One month after implanting, the results of inflammation score in the control group there were three eyes of three point, four of two point, three of one point; in the experimental group there were two of two point, four of one point,three of zero point; in the blank group there were two of two point, three of one point, one of zero point. Statistics showed that the difference of inflammatory response between the blank group and the experimental group and the control group was significant (p <0.05),and the difference between the blank group and the experimental group and the control group was not significant (p> 0.05).3 Collagen Assessment3.1 One week after the implanting, fibers hyperplasied irregularly around plates of three groups, most of those were composed of the yellow and red typeⅠcollagen fiber which had high refractive index, and distributed widely, typeⅢcollagen fiber that had green fine fiber of weak refraction was part of the mixture, yellow fiber spreaded closely around periosteal areas, there was no significant difference between the experimental group and the control group.3.2 One month after implanting, hyperplasia fiber around the bone ruled in the experimental group, from the polarizing microscope we could see that the yellow typeⅠcollagen fiber with strong refractive index distributed, during which the green typeⅢcollagen fiber with weak refractive index had the distribution of a wide range. There were more typeⅠcollagen fiber in control group than in experimental group , and less typeⅢcollagen fiber,but more coarse.4 Immunohistochemistry Results4.1 One week after the implanting, in the experimental group and control group very strong positive brown particles, and deep-colored, widely distributed in the hyperplasia soft tissue. In blank group there were fewer brown positive particles, and light-colored. 4.2 One month after implanting, in experimental group and blank group there were very few brown positive particles, which distributed among the outer membrane of the fibrous tissue; in control group, brown positive particles were medium density and deep colored , which distributed in the fibronectin regional of inflammatory response.5 Image Analysis Results5.1 One week after the implanting, there were slightly higher positive particles in experimental group than in control group about the surface density, integral optical density and the positive rate, and there was not a significant difference (p> 0.05). That in the control group compared with the above-mentioned two groups was significant difference (p <0.05).5.2 One month after implanting, in control group positive particles of the surface density , integral optical density and the positive area rate was higher than that in experimental group and the control group. There was a significant difference (p <0.01) .6 Pathological Observation of Optic NerveIn three groups the soft tissue around the optic nerve were rules, and there were no obvious lesions;no obvious fibrous tissue and inflammatory cell infiltration surrounded optic nerve sheath; arachnoid lacunar was visible and no cells increased obviously ; fiber optic travelled in rules, and there were no conspicuously degeneration and glial cell proliferation.Conclusion: 1 Through breaking the lacrimal bone of rabbits in the top of the orbit ,we caused the bone defect, soft tissue injuries, and simulated the model of orbital blowout fracture to some extent. The model is ideal, and the surgery is simple, economical and practical. 2 The HA plates wrapped by amniotic membrane repair orbital fracture, in the postoperative early time(one week) there is no obvious anti-inflammatory effect, but in the repair of chronic phase (one month)it can be observed to have significant anti-inflammatory and anti- adhesion effect. 3 It is safe and effective to repair orbital fracture by using the HA plates wrapped by amniotic membrane. 4 We could consider to make use of HA plates wrapped by amniotic membrane to repair these injuries, such as orbital fracture of the larger, heavier adhesion, or old fractures like those patients needing the second surgery.