① The diameter of the injection pot is about 1~2cm. There is a metal plate at the bottom of the injection tank to prevent the puncture from being too deep or worn. There is a special one-way or two-way valve in the kettle, which can automatically close after liquid is injected to avoid overflowing from the pinhole.
② The connecting catheter is about 3mm in diameter and 5~ 15cm in length.
③ The expansion sac is the main body of the dilator, which can be divided into round, oval, kidney-shaped, half-moon, rectangular and cylindrical shapes, and its size can range from 10ml to 800ml. Expander-How does skin and soft tissue expand?
Skin and soft tissue expansion is generally divided into two stages.
The first stage of the operation is to embed the dilator under the skin or muscle of the site to be expanded. Before the operation, the size and shape of the dilator should be selected according to the position, shape, lesion range and the size and shape of the expanded normal skin, and its quality should be carefully checked before cleaning and disinfection. One operation can implant one or more dilators, and the second operation is to use new skin tissue to make the necessary repairs.
The second operation is to repair the skin defect with new skin tissue through skin flap transfer. ① The biological growth caused by the proliferation of skin cells on the surface of the dilator can still be retained after the dilator is taken out;
(2) The skin on the surface of the dilator expands elastically, and the dilator will partially retract elastically after being taken out;
③ The skin around the dilator moves towards the dilator, which is similar to the effect of large area subcutaneous peeling.
The proportion of skin and soft tissue from different sources in the total tissue produced by expansion is related to the expansion speed. Within a certain range, the faster the liquid injection rate, the smaller the proportion of biological growth. After the dilator is taken out, the tissue retraction ratio caused by expansion is not only related to the difference of expansion speed and individual skin elasticity, but also related to the expansion site. The parts with high retraction rate from high to low are: neck, face, trunk, limbs and scalp. The time to complete the injection is related to the expanded site, the size of the dilator and the area to be repaired. In most cases, it takes 1 to 3 months. The injection tank can be built-in or external.
When the pot is built in, the skin needs to be punctured every time the liquid is injected, and it is sometimes difficult to find the pot in the later stage of expansion or it is inconvenient to handle if the pot is leaked; Putting the kettle outside can avoid puncturing the skin when injecting liquid, but it will cause infection, so strengthen nursing when expanding. The expansion bag has good expansibility and can be over-inflated beyond its volume. After the expansion amount is enough, the expansion can be maintained for 1 ~ 2 weeks, so that the skin and soft tissue can be fully expanded and the skin retraction can be reduced. After the completion of the whole expansion process, the second operation can be performed, and the expander is taken out to form an expanded flap, and the tissue generated by expansion is used to repair the defect area, while retaining enough tissue to cover the donor area. If one expansion is not enough to repair all the diseased areas, the expander can be buried under the expanded flap again in the second stage of operation for "relay" expansion; You can also bury an expander under the expanded flap and perform relay expansion after the wound heals for half a year.
After the wound healed in the second stage operation, measures should be taken to prevent scar hyperplasia, expand and resist skin flap contracture, such as elastic sleeve, neck brace and bracket. The expanded flap became hard in the early postoperative period and tended to retract. Generally, it can soften and restore natural elasticity 6 months after operation. The indications of skin and soft tissue expansion are very wide, and the parts of body surface defects that need additional skin repair can be used.
Scalp is the best place for dilator application. As long as the bald area does not exceed 2/3 of the whole scalp, there is hope to cover the whole scalp after expanding the remaining normal scalp. After scalp expansion, although the area has increased, the total number of hair has not increased, but the hair spacing has increased, which is actually the redistribution of hair. Postoperative hair is slightly thinner than normal, but it is generally not visible after long hair. All kinds of scars, whether located in the head, face or trunk and limbs, can be repaired by skin and soft tissue expansion as long as the scar area is small and normal skin is available for expansion.
At present, all kinds of scars, especially those after burns, are the most common diseases of skin and soft tissue expansion. Skin and soft tissue expansion is also the first choice for the treatment of many deformities after burn. For patients with large area burn deformity and insufficient donor site, skin and soft tissue expansion can be used to pre-expand the donor site, which can not only increase the amount of donor skin, but also directly suture the donor site. The expanded skin can be transplanted with full-thickness and medium-thickness skin grafts, and the survival quality is better than that of ordinary skin grafts. The application of dilation before otorhinoplasty has a very good effect. Breast is one of the common parts of expansion, which can be used to implant breast prosthesis in prefabricated space. Skin and soft tissue expansion can also be combined with traditional skin flap transplantation and skin tube transfer technology to increase the donor area and reduce donor deformity, thus improving the treatment effect.
The disadvantages of skin and soft tissue expansion are that the operation needs to be carried out in stages, the treatment time is long, the cost is high, the swelling of the expansion site during expansion hinders the appearance, and there are some complications after operation. Complications of skin and soft tissue expansion include hematoma, infection, expander exposure, expander failure, pain, numbness and expanded skin necrosis, all of which need timely and correct treatment. Some patients need another operation to remove hematoma or replace dilator, while others are forced to stop dilatation and have a second operation in advance. The incidence of complications in different parts varies greatly, which is related to local anatomical characteristics. Generally, the incidence of facial and neck complications is the highest, the scalp is the lowest, and the trunk and limbs are in the middle. With the progress of technology, the accumulation of experience and the improvement of expander quality, the incidence of complications of skin and soft tissue expansion is gradually decreasing.
Although skin and soft tissue expansion has some shortcomings, it is welcomed by patients and doctors because of its superior therapeutic effect and incomparable advantages of traditional methods. At present, this technology is quite mature, widely used in many fields of plastic surgery, and has become one of the most basic and commonly used treatment methods in plastic surgery.