Intra-abdominal Deep Inferior Epigastric Vessel Course Does Not Preclude Successful DIEP Flap Breast Reconstruction.

We present 2 patients in whom the course of the deep inferior epigastric vessels was intra-abdominal during deep inferior epigastric perforator (DIEP) flap breast reconstruction. Preoperative computed tomography angiography gave no indication of an unusual pedicle location. In both cases, pedicle dissection was completed safely without bowel injury, and reconstruction was completed successfully. Reconstructive surgeons need not abandon DIEP flap reconstruction upon discovering that the deep inferior epigastric vessels are intra-abdominal. Unfortunately, computed tomography angiography imaging does not identify this variant preoperatively. The risk of postoperative ileus after intra-abdominal pedicle dissection may be higher than the risk after dissection of retrorectus deep inferior epigastric pedicles, and thus it is reasonable to consider the use of prophylactic mesh in these cases.

Extended V-Y Advancement Flap Reconstruction of a Large Posterior Upper Midline Trunk Defect.

Large posterior upper trunk defects can be challenging to reconstruct. Trapezius or latissimus dorsi myocutaneous flaps are principally utilized for reconstruction; however, some defects may not be amenable to this standard approach. Here, we describe a patient with a full-thickness skin and subcutaneous tissue loss of the upper back and inferior cervical region after dermatofibrosarcoma protuberans resection. A large, extended V-Y flap was used for closure of this wound secondary to its location, size, and orientation. This approach preserves shoulder function, allows for readvancement of the flap as needed, and is a reconstructive option for patients with large upper back defects.

SPLIT rectus abdominis myocutaneous double free flap for extremity reconstruction.

A Mathes and Nahai type III muscle, such as the rectus abdominis muscle, can be utilized to cover two separate wounds simultaneously utilizing its dual blood supply thereby minimizing donor site morbidity and operative time. We report a case for treatment of bilateral Gustillo type IIIB lower extremity injuries treated with a single rectus abdominis muscle split into two free flaps, with one based on the deep inferior epigastric vessels and one on the superior epigastric vessels to cover the contralateral wound. In our patient, both lower extremity wounds were covered with muscle flaps from the same donor site in a single operation, salvaging both limbs with progression to unassisted ambulatory status. We show in this case report that the utilization of the vascular anatomy of the rectus muscle allows for division of the flap into two flaps, permitting preservation of the contralateral abdominal wall integrity and coverage of two wounds with a single muscle.

Foam pore size is a critical interface parameter of suction-based wound healing devices.

BACKGROUND: Suction-based wound healing devices with open-pore foam interfaces are widely used to treat complex tissue defects. The impact of changes in physicochemical parameters of the wound interfaces has not been investigated. METHODS: Full-thickness wounds in diabetic mice were treated with occlusive dressing or a suction device with a polyurethane foam interface varying in mean pore size diameter. Wound surface deformation on day 2 was measured on fixed tissues. Histologic cross-sections were analyzed for granulation tissue thickness (hematoxylin and eosin), myofibroblast density (α-smooth muscle actin), blood vessel density (platelet endothelial cell adhesion molecule-1), and cell proliferation (Ki67) on day 7. RESULTS: Polyurethane foam-induced wound surface deformation increased with polyurethane foam pore diameter: 15 percent (small pore size), 60 percent (medium pore size), and 150 percent (large pore size). The extent of wound strain correlated with granulation tissue thickness that increased 1.7-fold in small pore size foam-treated wounds, 2.5-fold in medium pore size foam-treated wounds, and 4.9-fold in large pore size foam-treated wounds (p < 0.05) compared with wounds treated with an occlusive dressing. All polyurethane foams increased the number of myofibroblasts over occlusive dressing, with maximal presence in large pore size foam-treated wounds compared with all other groups (p < 0.05). CONCLUSIONS: The pore size of the interface material of suction devices has a significant impact on the wound healing response. Larger pores increased wound surface strain, tissue growth, and transformation of contractile cells. Modification of the pore size is a powerful approach for meeting biological needs of specific wounds.

Waveform modulation of negative-pressure wound therapy in the murine model.

BACKGROUND: Negative-pressure wound therapy applied with a porous foam interface has been shown to accelerate granulation-tissue formation when a cyclic application mode of suction is applied, but the optimal waveform has not been determined. The authors hypothesized that changes in the suction waveform applied to wounds would modulate the biological response of granulation tissue formation. METHODS: A vacuum-assisted closure device (Kinetic Concepts, Inc., San Antonio, Texas) was applied to full-thickness wounds in 48 male diabetic mice (C57BL/KsJ-Lepr db), which were treated with six different waveforms: square waveforms of 125 mmHg of suction for 2 minutes, alternating with 50 mmHg of suction for 2 minutes, 5 minutes, or 10 minutes; triangular waveform with a 7-minute period oscillating between 50 and 125 mmHg; and static suction at 125 mmHg or static suction at 0 mmHg (occlusive dressing). Wounds were quantitatively evaluated for granulation tissue thickness as well as the number of proliferating cells and the number of blood vessels of the newly formed granulation tissue. RESULTS: At 7 days, the continuous and triangular waveforms induced the thickest granulation tissue, with high rates of cellular proliferation and blood vessel counts compared with square wave and occlusive dressing control wounds. Decreasing square waveform frequency significantly increased granulation tissue thickness, cellular proliferation, and blood vessel counts. CONCLUSIONS: Waveform modulation has a significant effect on granulation tissue formation, angiogenesis, and cellular proliferation in excisional wounds in diabetic mice. The rapid change in pressure seen in our square wave model may be detrimental to granulation tissue formation.

Microdeformation of three-dimensional cultured fibroblasts induces gene expression and morphological changes.

BACKGROUND: Vacuum-assisted closure induces microdeformations of the wound surface and accelerates healing of complex wounds; however, a thorough understanding of the biology of cellular mechanotransduction is lacking. We hypothesized that fibroblast shape and function can be altered in an in vitro vacuum-assisted closure device. METHODS: A 3-dimensional fibrin matrix with cultured murine fibroblasts and an intervening polyurethane foam was exposed to 125 mm Hg suction and compared with similar wells without suction. We measured fibroblast proliferation and morphology using fluorescence microscopy and gene expression change using real-time reverse-transcriptase polymerase chain reaction at 24, 48, and 72 hours. RESULTS: Wells exposed to suction induced significant proliferation of fibroblasts and morphologic changes visible by larger, rounder, and notable dendrite-like branching and process extensions. Type 1 collagen alpha 1 (COL1A1), fibroblast growth factor 2 (FGF2, bFGF), and transforming growth factor beta 1 (TGFß1) were all up-regulated after 48 hours of exposure to suction. Smooth muscle actin alpha 2 (Acta2, α-SMA) was up-regulated after 72 hours. CONCLUSIONS: Microdeformations produced by the combination of polyurethane foam and suction are associated with increased fibroblast proliferation and up-regulation of gene expressions in fibroblasts.

Analysis of neuropeptides in stretched skin.

BACKGROUND: Mechanical forces modulate wound healing and scar formation through mechanotransduction. In response to mechanical stimulation, neuropeptides are released from peripheral terminals of primary afferent sensory neurons, influencing skin and immune cell functions and increasing vascular permeability, causing neurogenic inflammation. METHODS: A computer-controlled device was used to stretch murine skin. C57Bl6 mice (n = 26) were assigned to a cyclical square-wave tensile stimulation for 4 hours or continuous stimulation for 4 hours. Stretched skin was analyzed for expression of the neuropeptides, substance P and calcitonin gene-related peptide, their receptors (NK1R and calcitonin gene-related peptide receptor component protein), and growth factors (nerve growth factor, transforming growth factor beta1, vascular endothelial growth factor, and epidermal growth factor) using immunohistochemistry and real-time reverse-transcriptase polymerase chain reaction. RESULTS: Cyclical stimulation resulted in a significant increase in expression of neuropeptides and growth factors, whereas the corresponding peptide receptors were down-regulated. Transcription of neuropeptide mRNA was elevated in stretched skin, which proves that neuropeptides are released from not only peripheral terminals of nerve fibers but also resident skin cells. CONCLUSIONS: The authors' results suggest that skin stretching may alter cell physiology by stimulating neuropeptide expression, and that cyclical mechanical force may be more effectively stimulating mechanosensitive nociceptors or mechanoreceptors (mechanosensors) on cells.