Cycle Load Lead To Patellar Tendon Bone Tendon Junction Injury Animal Model

Bone tendon junction (BTJ) injuries is a common clinical problem in athletes and normal people, it is also one of the difficult issues for research. In order to reveal the histopathological changes and the factors that delayed BTJ injury healing, it is necessary that eatablish an BTJ injury model. In this study, the Nakama's cycle load model was modified in stimulation intensity and period in cycle load group, and injury follow by cyclic load group. Establish a BTJ injury models is the major purpose of thhis study, the model should be efficient, repeatable and mimic the clinician.16 matual ( 18 weeks) female New Zealand rabbits, were randomly divided into Cycle Load group (CL, n = 8), Injuried Cycle Load (ICL, n = 8). Left hind limbs for experimental, and the contra-lateral hind limbs of the CL group as Control group (CON, n = 8). CL group performed a training program, it trained 3 times per week, 2 hours per time in 4 weeks, The stimulation load intensity was 7.06 N/S. ICL group' patella-patellar BTJ was puncture and injected 0.2 ml rabbits' self blood into the injuried area, followed by cyclic load after 48 hours. Specimens were harvested in week 4, and fixed in formalin, decalcified in ethylenediaminetetraacetic, then were dehydrated and embedded in paraffin. The samples were sectioned in the sagittal plane, H&E stained and deseribed by fibra alignment, cell intensity, average width of fibrocartilage zone and new bone area.Results: compared with CON group, the CL group's histology showed significantly tendon hyaline changed, fibral alignment was poorer, and CL gropup's tendon cell intensity and average width of fibrocartilage were also significantly higer or thicker. The tidemark profile of BTJ showed typical " flow form change " or disappeared, or calcificated. The fibrocartilage zone showed significantly thicker hyaline changed, calification or hyperosteogency, and chondroid. The results of ICL group sectionds showed similar change of CL group, but the arrange of fibers and cells were more disorder, tidemark disappeared completely, but no significantly bone hyperplasia compared to CL group.Conclusions:â‘ It was confirmed that the injuries in BTJ existed in histiology at week 4 by the morphologic changes in BTJ in CL group and ICL group.â‘¡The fibrocartilage thickness and cell density in CL group and ICL group also revealed the successful establishment of the modified cyclic load injury model and injury followed by cyclic load model.â‘¢These two BTJ injuried model were difficult to say which one was better than the other one.