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Tissue expansion offers the reconstructive surgeon a better option than the conventional methods of skin grafts or the transfer for non-hair-bearing, regional or microsurgical flaps for reconstructing large defects that cannot be repaired with adjacent hair-bearing flaps. Aspects of preoperative planning and technical factors of scalp expansion are presented to assist the clinician in managing these difficult reconstructive challenges.
OBJECTIVE: Elevated levels of tumor necrosis factor-alpha (TNF-alpha) protein and mRNA have been reported in adipose tissue from obese humans and rodents. However, TNF-alpha has catabolic and antiadipogenic effects on adipocytes. Addressing this paradox, we tested the hypothesis that paracrine levels of TNF-alpha, alone or together with insulin-like growth factor-I (IGF-I), support preadipocyte development. RESEARCH METHODS AND PROCEDURES: Cultured stromal-vascular cells from rat inguinal fat depots were exposed to serum-free media containing insulin and 0.2 nM TNF-alpha, 2.0 nM TNF-alpha, or 0.2 nM TNF-alpha + 1.0 nM IGF-I at different times during 7 days of culture. RESULTS: TNF-alpha inhibited adipocyte differentiation as indicated by a reduction in both immunocytochemical reactivity for the preadipocyte-specific antigen (AD3; early differentiation marker) and glycerol-3-phosphate dehydrogenase activity (late differentiation marker). Early exposure (Days 1 through 3 of culture) to 0.2 nM TNF-alpha did not have a long term effect on inhibiting differentiation. Continuous exposure to 0.2 nM TNF-alpha from Days 1 through 7 of culture resulted in a 75% increase in cell number from control. There was a synergistic effect of 0.2 nM TNF-alpha + 1 nM IGF-I on increasing cell number by Day 7 of culture to levels greater than those observed with either treatment applied alone. DISCUSSION: These data suggest that paracrine levels (0.2 nM) of TNF-alpha alone or in combination with IGF-I may support adipose tissue development by increasing the total number of stromal-vascular and/or uncommitted cells within the tissue. These cells may then be recruited to become preadipocytes or may alternatively serve as infrastructure to support adipose tissue growth.
A case is presented in which an extensive area of traumatically denuded skull bone was successfully closed using a tissue expanded, hair-bearing scalp rotation flap, following expander insertion on the third day after injury. No split skin grafting was required and, in view of the high quality of cosmesis achieved, it is recommended that the technique be considered for other cases of acute traumatic soft tissue loss.
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The structural and circulatory dynamics of expanded skin in connection with expander fillings were assessed in pigs following 7, 14, and 21 days of expansion by measuring the pressure of te fluid in the expander (Pexp) and the dermal blood flow. The results differed consistently on thoracic and abdominal sites. It was suggested that the stimulus to expansion be defined as the relative increase in extensible surface area of the expander. When plotting this value against Pexp, as measured at the end of injection, there was a good fit to an exponential curve. The area/Pexp relation was used to assess the connective tissue reaction around the expander; the reaction was most pronounced at 21 days. The decrease in Pexp after injection of fluid to 100 mm Hg showed that the tissue adapted rapidly during the first hour. Blood flow in the skin covering the expander was lower than on adjacent normal skin, and there was no increase during the three weeks of expansion. The decreases in blood flow were moderate even after injection of fluid until Pexp reached 100 mm Hg. It was suggested that the connective tissue capsule might protect the dermis from flow decrease.
OBJECTIVE: Unidirectional conduction block in the heart can occur at a site where the impulse is transmitted from a small to a large tissue volume. The aim of this study was to evaluate the occurrence of conduction block in a 2-dimensional and 3-dimensional computer model of cardiac tissue consisting of a narrow strand abruptly emerging into a large area. In this structure, the strand diameter critical for the occurrence of block, hc, was evaluated as a function of changes in the active and passive electrical properties of both the strand and the large medium. METHODS: The effects of changes in the following parameters on hc were analysed: (1) maximum sodium conductance (gNamax), (2) longitudinal (Rx) and transverse (Ry) intracellular resistivities, and (3) inhomogeneities in gNamax and Rx and Ry between the strand and the large area. Three ionic models for cardiac excitation described by Beeler-Reuter, Ebihara-Johnson, and Luo-Rudy ionic current kinetics were compared. RESULTS: In the 2-dimensional simulations, hc was 175 microns in Ebihara-Johnson and Beeler-Reuter models and 200 microns in the Luo-Rudy model. At the critical strand diameter, the site of conduction block was located beyond the transition, i.e. a small circular area was activated in the large medium, whereas with narrower strands conduction block occurred within the strands. The decrease of gNamax resulted in a large increase of hc. This increase was mainly due to the change of gNamax in the large area, while hc was almost independent of gNamax in the strand. Changing Rx had no effect on hc, whereas the increase of Ry decreased hc and reversed conduction block. Inhomogeneous changes of Rx and Ry in the strand versus the large medium had opposite effects on hc. When the resistivities of the strand alone were increased, hc also increased. In contrast, the increase of the resistivities in the large area reduced hc. In the 3-dimensional model, hc was 2.7 times larger than the corresponding 2-dimensional values at the various levels of gNamax and resistivity. CONCLUSIONS: (1) At physiological values for active and passive electrical properties, hc in the 2D simulations is close to 200 microns in all three ionic models. In the 3-dimensional simulations, hc is 2.7 larger than in the 2-dimensional models. (2) The excitable properties of the large area but not of the strand modify hc. The decrease of intercellular coupling in the large medium facilitates impulse conduction and reduces hc, while the same change in the strand increases hc. (3) Occurrence of conduction block at an abrupt geometrical transition can be explained by both the impedance mismatch at the transition site and the critical curvature beyond the transition.
A traditional custom has been employed in a design of a new technique to expand a rudimentary auricle. The technique involves a full thickness incision of the blob of tissue and positioning of a spacer which is gradually expanded by means of a conical obturator. The technique provides a large amount of local tissue that can be used in helix and ear lobe reconstruction. An illustrative case is reported.
A 22-year-old musician requested the correction of his digital syndactyly deformity without the use of skin grafts. Failure of the original correction to heal primarily resulted in the formation of dense scar tissue. A small, custom-designed tissue expander was inserted within the web space and was slowly expanded. The additional expanded tissue permitted reconstruction of the web space and the sides of the fingers without the use of skin grafts.
The effect of controlled skin expansion in blood flow was investigated using the dermofluorometer. Twenty-eight subcutaneous pockets in seven pigs were divided into three groups. Group 1: subcutaneous pockets with a gradually inflated 200-cc tissue expander over 12 days, then deflated and observed for 6 days. Group 2: subcutaneous pockets with a noninflated 200-cc tissue expander. Group 3: subcutaneous pockets elevated without placement of a tissue expander. Measurements taken 30 to 45 minutes after partial inflation of the tissue expander showed a decrease in blood flow while blood flow was increased 30 to 45 minutes after deflation of the tissue expander. The increase in blood flow, however, was not evident 6 days after the expander in group 1 was deflated.
A two-stage method suitable for reconstructing the lower part of the auricle and using an advancement-rotation flap of expanded cervical and postauricular skin is described. Expander shape and capacity should be selected after careful consideration of available donor sites and the amount of additional tissue required for reconstruction.
A contracted empty scrotum in a young man will not accept an artificial testis satisfactorily using any of the standard techniques. Previous operative scars, as from a failed orchiopexy, have often added to the difficulties. Greatly enlarging the scrotum by gradual distention of a tissue expander implanted in the contracted side has been successful in overcoming this problem, both cosmetically and functionally.
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Treatment of giant facial congenital melanocytic nevi (CMN) is recommended due to the potential for malignant degeneration, although therapy may be complicated because of cosmetic and functional considerations and the results problematic. We present the case of a 2-year-old child with a giant CMN of the scalp, excision of which was facilitated by the use of a tissue expander. This technique allows the creation of skin similar in appearance and type to that immediately adjacent to the defect. The giant CMN, which covered approximately one third of the scalp, was excised and simultaneously resurfaced with the remaining expanded normal scalp.
This article discusses the use of a permanent saline-filled expander for breast reconstruction incorporating on the anterior surface a filler valve that can be located by nonoperative means. The self-sealing filler valve has a well-marked design that is particularly amenable to ultrasound detection. This results in the capacity to inflate or deflate the prosthesis at will. Sixty patients were operated on and 123 submuscular custom-made prosthetic expanders were implanted. Seventy-four percutaneous volumetric changes were performed without significant complications. Follow-up studies for more than 6 years are presented. The primary advantage of this prosthesis is its capability for percutaneous access under local anesthetic to produce volumetric changes. The prosthesis is permanent and does not have to be replaced as normal tissue expanders do. Only 1 operation is necessary. In addition, capsule contracture and spontaneous deflation rates are within an acceptable range.
Inflammatory myopathies (IMs) are relatively common in dogs, and canine IMs have many similarities to human IMs. The aim of this work was to analyze aspects of the pathogenesis of canine IM with an ultimate goal of establishing canine IM as a model for human IM. Muscle biopsies from 16 dogs with a histological diagnosis of IM were analyzed to determine degree of muscle regeneration, presence of eosinophils, expression of selected cytokines and chemokines, and extent of fibrosis. Regeneration, as shown by staining for developmental myosin heavy chain, was more extensive than evidenced with hematoxylin-eosin staining in most cases of canine IM. Expression of mRNA encoding transforming growth factor-beta (TGF-beta) and eotaxin 3 was upregulated in all cases evaluated. Eosinophils were abundant in most cases, and the connective tissue was variably expanded, as demonstrated by the distribution of the ubiquitous extracellular matrix proteins collagen VI and fibrillin. The extensive regeneration demonstrates that muscle may survive this adverse environment if inflammation and fibrosis can be stopped or reduced.
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A speedy and simple technique of wound closure for use with multiple casualties is described. K wires are passed through the skin on either side of the wound and these are connected across the wound by silver wire. Daily twisting of the silver wire slowly approximates the wound edges to healing.
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