| BackgroudRotator cuff injury is a common disease in orthopedic clinical practice.In recent years,with the improvement of national life and developing national sports extensively,such kind of injury incidence is rising trend year by year which seriously affect the patient's quality of life.Bone-Tonden Junction(BTJ)was thought to be key parts in the process of rotator cuff injury healing.Clinical data shows that,the rotator cuff heals in the form of scar to restore by surgical repair,this form of early callus biomechanical strength was far below the normal level,it is easy to tear again,causing surgery failure.It has become the focus of the surgeon to promote the normal healing of rotator cuff.And in this regard animal experiments and research is involved,which makes building a rotator cuff BTJ injury-healing animal models particularly important.On this basis,this study intends to construct the SD rat supraspinatus and Achilles tendon BTJ damage repair models,comparing the operation difficulty of the two models,researching the postoperative BTJ biomechanical strength and histoembryology in the purpose of exploring a more scientific and effective experimental method for the further research.ObjectiveIn this study,we are to build the SD rats unilateral supraspinatus and Achilles tendon damage/repair model and to Observe the healing process,comparing operation difficulty,the BTJ biomechanical strength and histoembryology in the different period of the healing process between the two models.Our purpose is to test whether this two models can replace each other in the experiment.Methods1.Experimental design96 male SD rats(weighed 150-200 g on average)were chosen for this experiment randomly provided by the Second Military Medical University Animal Center.64 of them(randomly chosen)underwent the RC(32 rats,group NO.(2))and Achilles tendon(32 rats,group NO.(3))injury/repair simulated operation leaving another 32 SD rats untreated as the blank control group(group No.(1)).All the animals were fed in thesame environment and then 8 rats each time from each group were sacrificed at a time point after surgery(7d,14 d,21d,28d).The specimen which contains the whole shoulder(or ankle)joint was taken accordingly and sent to undergo the biomechanical,histological test in order to estimate the efficacy of the BTJ healing,comparing the similar degree between the process of two models BTJ healing.2.Surgical methodThe rat was anesthetized using 10% chloral hydrate saline solution by abdominal injection(0.4ml/100 g in weight).Then the rat is fixed on a customized board in prone position with its four limbs tied on the board rim.After skin preparation,disinfection and draping was completed,we made a transverse incision(approximately 3-4cm long)along the lower edge of the shoulder blade,separated the supraspinatus tendon gradually,and then we stripped the supraspinatus tendon from the great tuberosity with blunt avulsion.Next we used a towel clamp to make a oblique bone channel on the great tuberosity,then stiched the supraspinatus on its original location on the great tuberosity using transosseous knot-tying fixation.Finally we closed the wound carefully after fully flush of Physiological saline.We used the similar operation method as the RC group to create the Achilles tendon damage/repair simulated operation model,choosing rat's left posterior limb as operation target zone.3.Specimen harvesting and making8 rats were sacrificed in each group for specimen harvesting at 4 different time point(say 7d,14 d,21d,28 d after surgery).We took the whole shoulder blades and the humerus linked to it from operation side as specimens in RC group,and took tibia and its linked heel bone as specimens in Achilles tendon group.The same part was taken as well in the blank control group.Then specimens were sent to take undergo the biomechanical,histological test to estimate the efficacy of the BTJ healing.4.Observation method and results evaluationLiving condition:We compared their survival condition at different time point before the rats were sacrificed for specimen collection.The Incision healing(infection case happens or not)and range of motion was observed as well.HE staining observation:After the specimens of the BTJ were sent to do the fixation,decalcification,dehydration,washing,embedding,slicing and staining,we could observe their histologic characteristics.Masson staining observation : We observed the organization of collagen and the distribution of the muscle cells of the specimens of the BTJ in each time point.5.Statistical analysisStudent-Newman-Keuls test(SNK-q test)was applied when we tested the biomechanical data at different time point in order to make clear whether there is a difference in the two operation models.Results1.The overall resultsThe rats' activity declined as well as the range of motion of the joint post-operation after surgery.Rats in surgical group suffered walking gait abnormality(claudication).We found some of the surgical incisions dehiscenced,suppurative infection phenomenon was observed as well(about 15%).There was no obvious change in rats' diet condition.2.Specimen staining resultsWe found the BTJ specimens eventually had formed cicatricial tissue healing.No difference between the two groups' local cicatricial tissue generation in macroscopic observation.3.Biomechanical Test resultsThe overall trends of the surgical site BTJ healing showed gradually enhanced stretching resistance over time parts applied.At the same time point,the stretching resistance of specimens in surgery groups was significantly weaker than the control group,however.Statistical analysis used the SNK-q test method and showed that there was no significant difference between the RC group and Achilles tendon group(P>0.05),according to the ?= 0.05 level.ConclusionUnilateral SD rat Achilles tendon damage/repair model has a prospective result inthe features of simple operation,high success rate of surgery,fine postoperative survival rate and convenient sampling.The BTJ of Achilles tendon has no significant difference in biomechanical change and organizational form characters in the process of healing,compared with the BTJ of rotator cuff.On this occasion,we may establish animal model using the Achilles tendon damage/repair model for replacement in the future study of rotator cuff injury. |
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