| The tendon defect remains a big challenge which inhibits the development of hand surgery. Great progress achieved in recent years, though, there have been no satisfying treatment. As one of the common methods, tendon transplantation has many clinical limitations. The tissue engineering, which is being attached much importance, still matured not enough for the task due to the unqualified tissue material and the unsatisfying biomechanical properties of the reconstructed tendons.The technique of limbs elongation threw light upon our probe of tendon defect treatment. The presumption was made of the broken tendons, which are cut in vivo, may be elongated by the efforts of both the tendon crust formed by the repaired paratendon membrane and the slow strain stress. The probe of the elongated area of the tendon were made to evaluate the possible application in tendon defect treatment.The model of rabbit archtendons with slow stress strain were firstly constructed in this experiment to investigate the associated tendon changes after the operations. The self-designed tendon elongators were used to strain slowly the tendon crust formed between the cut ends of archtendons. Forty-eight Japanese big-ear rabbits were used and divided randomly into two groups: the control group A and the compare group B. The right archtendons were studied in the third, sixth, ninth and twelfth weeks respectively with twelve rabbits for each week. A steel ruler was used to measure the length of the right archtendons of all the rabbits. The paratendon tissue was cut transversely and stitched with 8-0 wires under a microscope. The broken ends of tendons were marked with steel wires. The elongators were set in the right limbs of rabbits. To avoid the over seperattion of the broken ends, the 1# wire were used to stitch the skin and the tendons crossly before the close of the skin. The stitch wire would be removed on the seventh day after the operation.The tendon elongation for the control group were to begin on the seventh post-operation day and lasted three weeks with a certain ratio of 1mm/day. The total elongated length was expected to be 2cm. There was no elongation for the compare group.The changes of the length, diameter and color of tendons were observed visually in the different weeks respectively. The steel wire marks were x-rayed to show the length elongated. Under a microscope were detected of the blood circulation on the surface of paratendon membrane and the adhesion between tendons and surrounding tissue. The paratendon membrane thickness were measured with Germen Leica Q500 imagine-analysis system. The light microscope and the electronic microscope were also used to observe the histological changes of the elongated area after the continuous strain. At last, all the tendons were tested of their biomechanics with the REGER Mechanical Testing Instrument.The results showed: 1.The tendons could be elongated under the slow strain stress.2. As the strain lasted, the paratendon membrane of the elongated area turned to be thinner and the adhesion with the surrounding tissue were lessen.3.The vessels in the paratendon membrane of the elongated area became fewer with the strain stress 4. In the third week, there was no degeneration and necrosis of the elongated tissue of the control group. The tissue were mainly composed of many cells and a few collagen fibers and rich capillaries. The cells included inflammation cells, lymph cells, plasma cells, fibroblast cells. The collagen fibers inside were arranged out of order. The electronic microscope showed fibroblast cells had regular pattern.There are rich plasmosome and endoplasmic reticulum.There was no statistical difference to that of the compare group. In the sixth week, the inside cells and capillaries became fewer while the fibroblast cells turned to be matured. And the collagen fibers were more. The cell number of the compare group remained as before but the collagen fibers were more than that in the third week. The capillaries of the compare group were as many as before. In... |
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