Most surgeons fill the expanders intraoperatively with sufficient saline to eliminate dead space and tamponade raw surfaces to help prevent postoperative bleeding. There's, nevertheless, an alternative to traditional prolonged expansion. Immediate intraoperative expansion combined with broad undermining of the defect can help decrease the tension that occurs on the distal parts of a local flap.
In rapid expansion, the skin initially expands because of its elasticity and also the displacement of interstitial fluid. Within minutes, the alignment of the collagen fibers changes due to the stretch. This process yields up to 20% more tissue for flap coverage. Intraoperative expansion is indicated for relatively small defects, such as in coverage of defects of the ear.
Although tissue expansion does not increase the number of hair follicles, the size of the hair-bearing region can be doubled with out a noticeable decrease in hair density. As such, tissue expansion might be used a means of treating male pattern baldness in addition to reconstructing the scalp. Expanders are most commonly placed in the occipital or posterior parietal regions. They should be placed under the galea, superficial to the periosteum.
It generally requires 6-8 weeks to complete the expansion in adults, and up to 12 weeks in kids. Radial scoring of the galea at the time of surgery can speed the procedure. Once the expansion is complete, flaps are advanced or transposed, ideally based on named arteries of the scalp. It is important to orient flaps so that the correct direction of hair growth is maintained. Even though galeal scoring or capuslotomy incisions can be useful, wide undermining is really a safer technique of recruiting tissue.
The brow position is probably the most important structure to preserve during forehead expansion. When possible, two or more expanders are used with incisions hidden within the hairline. For mid-forehead lesions, bilateral, temporal expanders are utilized, and also the skin is advanced medially based on the superficial temporal arteries. Expanders should be placed deep to the frontalis muscle. Expansion can usually begin 7-10 days postoperatively. When a large forehead flap is needed for nasal reconstruction, the forehead skin may be pre-expanded prior to flap transfer.
The skin of the neck and face is fairly thin. As a result, multiple expanders with smaller volumes are preferable to a single large expander. In general, however, a single larger expander is preferable to several smaller expanders. Careful planning is essential in determining where to location the expanders, and where incisions should be located. Considerations like preserving aesthetic units, matching skin color, avoiding distortion of the eyelids and oral commissure, and facial symmetry are all important. The expander is generally placed above the platysma muscle in order to steer clear of risk of facial nerve injury and to keep the flap from being excessively bulky.
The expanded flaps may be advanced, rotated, or transposed. Incisions should be placed in skin creases like the nasolabial fold. Expanding the hairless skin adjacent to the mastoid region can increase the available tissue for reconstructive procedures of the ear. The skin above the clavicle may be expanded to provide full-thickness skin grafts to the face.
Unlike the head and neck, you will find very few critical landmarks on the trunk that must be preserved. Aside from the breast and nipple-areola complex, distortion of the skin and soft tissues of the trunk is well-tolerated. For defects requiring excision, multiple expanders surrounding the defect are often employed. Many myocutaneous flaps of the trunk, like the latissimus dorsi, TRAM and pectoralis flaps, can be pre-expanded in order to increase their size and facilitate donor website closure. Expanders may also be utilized to expand the skin of the abdomen for use as a donor website of full-thickness skin grafts.
Tissue expansion in the extremities has been reported to have a higher complication rate in comparison to other regions and therefore ought to not be a first option among the reconstructive options. The blood supply and drainage of the extremities is inferior to that of the trunk and head. This predisposes limbs, especially below the knee, to an increased rate of infection and wound complications. Several expanders are generally needed in the extremites.
Correct placement and filling of tissue expanders has a steep learning curve. With expertise, the complication rate drops dramatically. Among all patients, the major complication rate is about 10% and includes implant exposure, deflation, and wound dehiscence. Minor complications also occur in about 10% of patients. These include filling port problems, seroma, hematoma, infection and delayed healing.
Patients under the age of 7 have the highest risk of complications. One explanation for this is that young kids are more prone to expander rupture due to external pressure on the expanded skin. Expansion in the extremities caries twice the risk of complication compared to other regions. The use of tissue expansion in burn reconstruction and soft tissue loss has a 15-20% major complication rate, whereas for congenital nevi it's 5-7%. Finally, tissue that has undergone serial expansion (two or more prior expansions) is at a higher risk for a main complication.
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