Study On Repair Of Tendon-bone After Reconstruction For Acute Ruptured Rabbit Rotator Cuff Under Stress

Rotator cuff is a sleeve-like structure, also known as tendon sleeves which is consist of the tendon fibers the supraspinatus muscles, infraspinatus muscles, subscapularis, and teres minor muscles that are attached to the humeral head from anterior, superior and posterior surfaces.Now, injuries of rotator cuff are the most common clinical diseases of the musculoskeletal systems, which is about 17-41 persons per 100 patients of shoulder, and they have been the the main causes of pain of shoulder jiont which are impacting on the lives and work of the patients. In the injureis of these tendon fibers, the injury of supraspinatus tendon is the most common, the site where is often only about lcm nera insertion. So,the difficultis lie in the reconstruction of insertion and the repair of postoperative tendon-bone. At present, some documentation has confirmed that the appropriate stress stimulation can promote the repair of postoperative tendon-bone,but the mechanisms are not unknown.Viewd from physical perspective the tendon-bone insertion is a mechanical weak point. In the normal state,tendon-bone insertion has good tensile strength, the stress can gradually transfer from tendon to bone or from bone to tendon, so that it can avoid stress-concentration at some point, thus it prevents tendon-bone from rupturing at the site of insertion. Therefore, when the tendon-bone is broken, the goal of reconstruction should be to restore the normal compound structure of tendon-bone.Some studies on histologis of animal and human found that perfectly restoring the normoal compound structure of tendon-bone was very difficult, although the surgical techniques were very good use reconstructing the insertion of tendon- bone,yet the postoperative tendon and bone could not composite greatly, but in terms of early or late repairing period.Until now, the current technology can still not guarantee the successful reconstruction for tendon-bone structure and completely avoid the occurrence of avulsion again. Therefore, the postoperative functional recovery has become very important, and the most captical thing is to restore the normal mechanical properties of the postoperative tendon-bone,so that it can recover the normal physiological functions as the whole body.In the clinical treatment for the injuries of tendon-bone, some people have already found that moderate exercises can promote the repairs of the injuried soft tissues such as muscles, ligaments,tendons, and so on. However,according to current principles of restoration and rehabilitation, the effect is often less than the expected and may lead to recurrence of re-injury and secondary instability. Of course, these can not deny the advance of the methods and the enhancement of the effect of the current clinical treatment on injuries of tendon-bone. As for the treatment is good or no,it lies in many reasons.First, the mechanisms of injuries and repairs of the tendon-bone are still unclear;Second, the methods of treatment and diagnosis on injuries of tendon-bone remain to continue to be explored and researched, as possible as early to judge accurately the site and the extent of injuris,in order to we take appropriate methods treatment on them; Finally, the opportunities of functional recovery and exercises are still not enough timely to be grasped, and the measures of rehabilitation and the degree of exercises are still not clearly standarded。So, often things go athwart, we can not achieve the expected results, and even add a new injury.In summary, the repair mechanisms of postoperative tendon-bone of rotator cuff after injury has not been yet entirely clear, the biomechanical properties of tendon-bone structure of rotator cuff, are still furtherly needed to research, new diagnostic and treatment methods are still furtherly needed to explore.On the basis of the above, this topic mainly study on the repair of tendon-bone after reconstruction for acute ruptured rabbit rotator cuff under stress,and which were divided in four parts:The first part:The construction of animal model of rabbits with postoperatibe acute ruptured rotator cuff tendon-bone and the evaluation of iconography in repairing under stress. Objective:Set up animal model of rabbits with postoperatibe acute ruptured rotator cuff tendon-bone under stress, and evaluate the iconography in repairing under stress. Methods:28 adult male New Zealand white rabbits (2.0-2.5kg) were randomly selected to be use seting up animal models in the experiment. Before operation,2 rabbits were randomly selected to conduct scans iof X ray, MRI and ultrasound examination, then they were sacrificed in order to know about the normal anatomy. Remained 26 rabbits underwent bilateral amputation of supraspinatus tendon and parallel reconstruction for supraspinatus tendon, successfully construct the animal models of post-reconstructive acute ruptured rabbit rotator cuff. After operation, they were imbolized with plaster for 1 week, and then removed the plaster.2 rabbits were randomly selected for conducting the examination of X ray, MRI and ultrasound. Remained 24 rabbits were randomly divided into 2 groups:stress group and non-stress group,12 in each group. Non-stress group, caging, free; stress group will begain to be trained with bilateral shoulder after removal of plaster, so completely set up animal models of rabbits with postoperatibe acute ruptured rotator cuff tendon-bone in repairing under stress. Specific training programs as follows:2ed week after operation, trained 1 time every other day and 5min per time; 3rd to 4th weeks after operation, trained 1 time every day and 15min per time; 5th to 6th weeks after operation, trained twice every day and 10min per time; 7th to 8th weeks after operation, trained twice every day and 20min per time. Respectively the 1 fianl day of 2,4,6,8 weeks after operation, randomly selected 3 rabbits in each group and conducted examination of X ray, MRI and ultrasound.Results:(1) X-ray test results:2 weeks after operation, at the site of the rabbit supraspinatus tendon-bone little callus appeared, the line of combined bone and tendon was fuzzier than before.4 weeks after operation, the callus at the site of tendon-bone surface in the strss group were plump and dense than in non-stress group,then tendinous structure of the two groups showed no specificity.6 weeks after operation, the strcture of combined the bone and tendon was along the longitudinal axis of supraspinatus tendon with a clearer direction, the line of combined bone and tendon was more vague than before.8 weeks after operation, at the site of the rabbit supraspinatus tendon-bone the combined tissues was more compact than before, tendinous structure did not change significantly. The line of combined bone and tendon was more vague. (2) MRI test results:2 weeks after operation, T2WI shows that the crack was evident at the site of the rabbit supraspinatus tendon-bone and it run through the full thickness of tendon. The hematoma appeared at one side of the shoulder of one rabbit in stress group which showed like liquid signal.4weeks after operation, T2WI shows that the areas of the low signals of the tissues connected tendon and bone were slightly larger and the signals of synovial fluid reduced more visible in stress group than in non-stress group.6 weeks after operation, T2WI shows that the areas of the signals of the tissues combined tendon and bone were larger than before in stress group than in non-stress group. And the high signals surrounded by synovial fluid decreased significantly in stress group, but it was no significant difference between the two groups.8 weeks after operation, T2WI shows that the high signals of the crack still appeared,but they significantly reduced. The medium signals of the tissues combined tendon and bone were more chaotic and rougher than normal state, Between the two groups, the areas of the healed tendinous structure were slightly larger in stress group, but the signals of synovial fluid were no significant difference. (3) Ultrasound examination results:2 weeks after operation, the echoes at the site of the rabbit supraspinatus tendon-bone were still discontinuous and the signals of inflammatory exudation appeared more evidently than before in stress group.4 weeks after operation, the linear continuous echoes appeared at the site of the rabbit supraspinatus tendon-bone in 2 groups, which showed more obvious in stress group than in non-stress group, and low echoes of synovial fluid decreased significantly in 2 groups.6 weeks after operation, the echoes at the site of the rabbit supraspinatus tendon-bone were still discontinuous in 2 groups, the area s of discontinuous echoes in stress group tendon significantly reduced.8 weeks after operation, the echoes at the site of the rabbit supraspinatus tendon-bone were still discontinuous in 2 groups, the area s of echoes of the tissues combined tendon and bone is more spacious than before, but the echoes of scar tissues was more apparent in stress group than in non-stress group. Conclusion:Relatively successfully set up animal models of rabbits with postoperatibe acute ruptured rotator cuff tendon-bone in repairing under stress, and the diagnosises of MRI, ultrasound on ruptured rotator cuff and the monitoring for the repairing process of tendon-bone are highly sensitive relatively.And a certain degree of stress stimulation plays an active role in the repairing of postoperative actue ruptured rabbit rotator cuff tendon-bone.The sencond part:The study of repair mechanisms of tendon-bone in rabbits with postoperative acute ruptured rotator cuff under stress. Objective:In order to know about the repair mechanisms of tendon-bone in rabbits with postoperative acute ruptured rotator cuff deeply under stress by analysis of the histology and expressions ofⅠ,Ⅲcollagen in repairing of tendon-bone. Methods:28 adult male New Zealand white rabbits (2.0-2.5kg) were randomly selected to be use seting up animal models in the experiment. Before operation,2 rabbits were randomly selected to conduct the assais of histoloy and expressions ofⅠ,Ⅲcollagen, then they were sacrificed. Remained 26 rabbits underwent bilateral amputation of supraspinatus tendon and parallel reconstruction for supraspinatus tendon, successfully construct the animal models of post-reconstructive acute ruptured rabbit rotator cuff. After operation, they were imbolized with plaster for 1 week, and then removed the plaster. 2 rabbits were randomly selected for conducting the assais of histoloy and expressions ofⅠ,Ⅲcollagen. Remained 24 rabbits were randomly divided into 2 groups:stress group and non-stress group,12 in each group. Non-stress group, caging, free; stress group will begain to be trained with bilateral shoulder after removal of plaster, so completely set up animal models of rabbits with postoperatibe acute ruptured rotator cuff tendon-bone in repairing under stress. Specific training programs as follows:2ed week after operation, trained 1 time every other day and 5min per time; 3rd to 4th weeks after operation, trained 1 time every day and 15min per time; 5th to 6th weeks after operation, trained twice every day and 10min per time; 7th to 8th weeks after operation, trained twice every day and 20min per time. Respectively the 1 fianl day of 2,4,6,8 weeks after operation, randomly selected 3 rabbits in each group and conducted the assais of histoloy and expressions ofⅠ,Ⅲ collagen. Results:(1)General observations:2 weeks after operation, the crack was evident at the site of the rabbit supraspinatus tendon-bone in 2 groups, but the suturation is good, no tears.4 weeks after operation, the inflammatory responsing significantly reduced in 2 groups, there were membranaceous things covering the outer tendon-bone, these phenomena was more evident in stress group than in non-stress group.6 weeks after operation, the crack rduced and the sutures were absorped partly, the membranous materials of tendon-bone outer layer were more tenacious than before, these phenomena was more obvious relatively in stress group. 8 weeks after operation, the crack rduced and the sutures were absorped more signicantly than before, and the membranous materials of tendon-bone outer layer were more tenacious than before, these phenomena was more obvious relatively in stress group. (2)The histology:2 weeks after operation,compared with the non-stress group, the stress group presented serious inflammatory response, which was obviously decreased at 4 weeks after operation.6 weeks after operation, the number of fibroblasts of the stress group was increased compared with the non-stress group.8 weeks after operation, the organizational structure study showed that fibroblasts in the stress were greater than that of the non-stress group, with orderly shape and arrangements.(3)The expressions ofⅠ,Ⅲcollagen:2 weeks after operation, collagen expressions of two groups all stained color, but they are no significant difference.4 weeks after operation, collagen expression of two groups also stained color, color in stress group was deeper than that in non-stress group, especially forⅢcollagen.6 weeks after operation, the areas of theⅠ,Ⅲcollagen expressions were wider than before.Collagen fibers were more orderly relatively in stress group than in non-stress group.8 weeks after operation, collagen fibers in stress group arranged more orderly relatively than in non-stress group,and I collagen stained more even than that of the III collagen which decreased significantly. Conclusion:The results demonstrated that a certain degree of stress stimulation can contribute to the repair of hitology of rabbit supraspinatus tendon-bone,and it can enhance the expressions ofⅠ,Ⅲcollagen of tendon-bone in repairing, so as to it can promote the whole repair of tendon-bone of rabbit postoperative acute rupteured ratator cuff.The third part:The study of expressions of BMP-2,b-FGF at the site of tendon-bone surface in rabbits with postoperative acute ruptured rotator cuff under stress. Objective:In order to know about the repair mechanisms of tendon-bone in rabbits with postoperative acute ruptured rotator cuff deeply under stress by analysis of the expressions of BMP-2,b-FGF in repairing of tendon-bone. Methods:28 adult male New Zealand white rabbits (2.0-2.5kg) were randomly selected to be use seting up animal models in the experiment. Before operation,2 rabbits were randomly selected to conduct the assais of expressions of BMP-2,b-FGF, then they were sacrificed. Remained 26 rabbits underwent bilateral amputation of supraspinatus tendon and parallel reconstruction for supraspinatus tendon, successfully construct the animal models of post-reconstructive acute ruptured rabbit rotator cuff. After operation, they were imbolized with plaster for 1 week, and then removed the plaster. 2 rabbits were randomly selected for conducting the assais of expressions ofBMP-2,b-FGF. Remained 24 rabbits were randomly divided into 2 groups:stress group and non-stress group,12 in each group. Non-stress group, caging, free; stress group will begain to be trained with bilateral shoulder after removal of plaster, so completely set up animal models of rabbits with postoperatibe acute ruptured rotator cuff tendon-bone in repairing under stress. Specific training programs as follows:2ed week after operation, trained 1 time every other day and 5min per time; 3rd to 4th weeks after operation, trained 1 time every day and 15min per time; 5th to 6th weeks after operation, trained twice every day and 10min per time; 7th to 8th weeks after operation, trained twice every day and 20min per time. Respectively the 1 fianl day of 2,4,6,8 weeks after operation, randomly selected 3 rabbits in each group and conducted the assais of histoloy and expressions ofBMP-2,b-FGF.Results:(1)The expression of BMP-2:2 weeks after operation, BMP-2 expression of two groups all stained color, but they are no significant difference.4 weeks after operation, BMP-2 expression of two groups also stained color, color in stress group was slightly even.6 weeks after operation, BMP-2 stained wider in 2 groups than before,and it was more even and ordered relatively in stress group than in non-stres group.8 weeks after operation,BMP-2 staining is orderer than before in stress group than in non-stress group. And between the site of closing to the bone and to the tendon, the difference of expressions of BMP-2 also decreased than before.(2) The expression of b-FGF:2 weeks after operation, b-FGF expressions of two groups also stained color, and the color with an area somewhat wider in stress group was slightly darker than thant in non-stress group.4 weeks after operation, Stress group staining was significantly deeper than non-stress group, the area of color was also obviously wider than non-stress group. A large number of fibroblasts with positive expression arranged parallelly along the long axis of tendon-bone in stress group.6 weeks after operation, two groups all stained color,the color in stress group was no significant changed than before, then it in non-stress group somewhat lighter.8 weeks after operation, two groups still stained positive, color was lighter than before in two groups, the phenomenon in non-stress group was more apparent.Conclusion:These findings showed that a certain degree of stress stimulation can enhance the expressions of BMP-2,b-FGF of tendon-bone in repairing, so as to it can promote the whole repair of tendon-bone of rabbit postoperative acute rupteured ratator cuff.The fourth part:the study of biomechanical properties of tendon-bone in rabbits with postoperative acute ruptured rotator cuff under stress. Objective In order to know about the biomechanical properties of tendon-bone in rabbits with postoperative acute ruptured rotator cuff deeply under stress.Methods:45 adult male New Zealand white rabbits (2.0-2.5kg) were randomly selected to be use seting up animal models in the experiment. Before operation,5 rabbits were randomly selected to conduct the assais of biomechanical properties, then they were sacrificed. Remained 40 rabbits underwent bilateral amputation of supraspinatus tendon and parallel reconstruction for supraspinatus tendon, successfully construct the animal models of post-reconstructive acute ruptured rabbit rotator cuff. After operation, they were imbolized with plaster for 1 week, and then removed the plaster.They were randomly divided into 2 groups:stress group and non-stress group,20 in each group. Non-stress group, caging, free; stress group will begain to be trained with bilateral shoulder after removal of plaster, so completely set up animal models of rabbits with postoperatibe acute ruptured rotator cuff tendon-bone in repairing under stress. Specific training programs as follows:2ed week after operation, trained 1 time every other day and 5min per time; 3rd to 4th weeks after operation, trained 1 time every day and 15min per time; 5th to 6th weeks after operation, trained twice every day and 10min per time; 7th to 8th weeks after operation, trained twice every day and 20min per time. Respectively the 1 fianl day of 2,4,6,8 weeks after operation, randomly selected 5 rabbits in each group and conducted the assais of biomechanical properties. All the biomechanical test results were descripted in the form of x±s, and they were analyzed by SPSS 13.0 statistical software. Such as initial length, cross-sectional area, maximum load, maximum strength and stiffness were first conducted the test K-S, if the results met with normal distribution or homogeneity of variance, the experimental data were analyzed by one-factor analysis of variance,and the results were tested by LSD,P<0.05 (α=0.05) was statistically significant. If the results did not meet with normal distribution or homogeneity of variance, the results would be tested by Welch and the final results were analyzed by DunnetT3, P<0.05 (α=0.05) was statistically significant. Result:Maximum intensity values in stress group were higher than that in non-stres group respectively at 2,4,6 weeks after operation(P=0.002 and P=0.000 and P=0.009).And the Maximum load values in stress group were higher than that in non-stres group respectively at 2,4,6 weeks after operation (P=0.001 and P=0.000 and P=0.000). The Stiffness values in stress group were higher than that in non-stres group respectively at 6,8 weeks after operation (P=0.000 and P=0.000).Conclusion:The results showed that a certain degree of stress stimulation can enhance the repair of biomechanical properties of tendon-bone in rabbits with postoperative acute ruptured rotator cuf, so as to it can promote the whole repair of tendon-bone of rabbit postoperative acute rupteured ratator cuff.