.1 Shorten The Injection Of The Experimental Study And Clinical Application Of Skin And Soft Tissue Expansion. Excessive Expansion Of The Skin Microcirculation And Microvascular Structural Changes And Security

Skin and soft tissue expansion has been a basic technique commonly used by plastic surgeons. Its main drawback is a long expansion period, which can be divided as injection (expansion) period and maintenance (Repose) period. Lots of methods have been proposed by scholars. They do animal experiments and use those methods clinically to prove their feasibility. However, the effect and mechanisms of maintain period still require further study. Skin expansion technique gets "extra" skin by the biomechanics property of the skin. Using biomechnical methods, through the study of the influence of different injection and maintain period on the expansion efficacy and shrinkage rate of skin, a rapid expansion method with relatively big expansion area is proposed in this article.Dogs were set up as animal models. Six areas, 5x8cm each, were symmetrically designed on dogs, marked by a machine for painting eyebrow. Expanders of 240 ml were implanted in every area. Four groups were divided: A. Injection of 2 weeks. B. Injection of 6 weeks. C. Sham-operation group. D. Blank control group. The first two groups were subdivided into three groups respectively according to maintain time: one week, two weeks and three weeks. Group A were injected every other day. Group B was injected once every week. The following index was measured on the second stage surgery: 1. The area of expanded skin. 2. Tension of skin in vivo. 3. Immediate retraction rate of skin. 4. Biomechnic properties of the skin, including: Tensil Strength and stiffness, stress-strain, stress-relaxation and creep . 5. Histology examination. 6. The collagen content of skin.Experimental results are as following:(l)The increase of central skin area of two week maintenance group and four week group is 91-94%and 99-100% respectively, which are significantly bigger than one-week maintenance group's 77-80%. Although the four-week maintenance group had bigger central area than the two-week group, it is not very significant. These indicate that: A. Maintenance of one week would obviously decrease the efficient expansion area; whereas maintenance of two weeks seems basically effective. B. Maintenance period is important both for increasing of expansion area and for reducing of immediate retraction rate.(2)Expanded skin has more tension than normal skin. The expanded flap reposed for 1 week has notable difference from other groups. When maintenance time increases, in vivo tension significantly decreases. Given the same maintenance time, there are no differences between rapid expansion and routine expansion. After the capusle of the expanded skin flap was removed, the in Vivo tension of skin rapidly reduced.(3)The immediate retraction rate of expanded flap is bigger than the blank control group and the sham-operation group. The expanded flap reposed for 1 week has notable difference from other groups. As the increasing of maintenance time, the...