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Objective: Successful foot and ankle soft tissue reconstruction is dependent on a clear understanding of the vascular supply to the foot. The aim of this study was to identify risk factors for reconstructive failure following foot and ankle free tissue transfer. Methods: The authors retrospectively reviewed their 17-year institutional experience with 231 foot and ankle free flaps performed in 225 patients to determine predictors of postoperative foot ischemia and flap failure. Postoperative foot ischemia was defined as ischemia resulting in tissue necrosis, separate from the reconstruction site. Results: Six (3%) patients developed postoperative foot ischemia, and 28 (12%) patients experienced flap failure. Chronic ulceration (P 50.02) and an elevated preoperative platelet count (P 50.04) were independent predictors of foot ischemia. The presence of diabetes was predictive of flap failure (P 50.05). Flap failure rates were higher in the setting of an abnormal preoperative angiogram (P 50.04), although the type and number of occluded arteries did not influence outcome. Foot ischemia was more frequent following surgical revascularization in conjunction with free tissue transfer and the use of the distal arterial bypass graft for flap anastomosis (P

Acellular dermal matrices (ADM) are commonly used in reconstructive procedures and rely on host cell invasion to become incorporated into host tissues. We investigated different approaches to adipose-derived stem cells (ASCs) engraftment into ADM to enhance this process. Lewis rat adipose-derived stem cells were isolated and grafted (3.0 × 105 cells) to porcine ADM disks (1.5 mm thick × 6 mm diameter) using either passive onlay or interstitial injection seeding techniques. Following incubation, seeding efficiency and seeded cell viability were measured in vitro. In addition, Eighteen Lewis rats underwent subcutaneous placement of ADM disk either as control or seeded with PKH67 labeled ASCs. ADM disks were seeded with ASCs using either onlay or injection techniques. On day 7 and or 14, ADM disks were harvested and analyzed for host cell infiltration. Onlay and injection techniques resulted in unique seeding patterns; however cell seeding efficiency and cell viability were similar. In-vivo studies showed significantly increased host cell infiltration towards the ASCs foci following injection seeding in comparison to control group (p < 0.05). Moreover, regional endothelial cell invasion was significantly greater in ASCs injected grafts in comparison to onlay seeding (p < 0.05). ADM can successfully be engrafted with ASCs. Interstitial engraftment of ASCs into ADM via injection enhances regional infiltration of host cells and angiogenesis, whereas onlay seeding showed relatively broad and superficial cell infiltration. These findings may be applied to improve the incorporation of avascular engineered constructs. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A:2939–2947, 2013.

Adipose-derived stem cells (ASCs) have the ability to release multiple growth factors in response to hypoxia. In this study, we investigated the potential of ASCs to prevent tissue ischemia. We found conditioned media from hypoxic ASCs had increased levels of vascular endothelial growth factor (VEGF) and enhanced endothelial cell tubule formation. To investigate the effect of injecting rat ASCs into ischemic flaps, 21 Lewis rats were divided into three groups: control, normal oxygen ASCs (10(6) cells), and hypoxic preconditioned ASCs (10(6) cells). At the time of flap elevation, the distal third of the flap was injected with the treatment group. At 7 days post flap elevation, flap viability was significantly improved with injection of hypoxic preconditioned ASCs. Cluster of differentiation-31-positive cells were more abundant along the margins of flaps injected with ASCs. Fluorescent labeled ASCs localized aside blood vessels or throughout the tissue, dependent on oxygen preconditioning status. Next, we evaluated the effect of hypoxic preconditioning on ASC migration and chemotaxis. Hypoxia did not affect ASC migration on scratch assay or chemotaxis to collagen and laminin. Thus, hypoxic preconditioning of injected ASCs improves flap viability likely through the effects of VEGF release. These effects are modest and represent the limitations of cellular and growth factor-induced angiogenesis in the acute setting of ischemia.

Large osseous defects of the upper extremity can be a challenging problem for the reconstructive surgeon. There are numerous treatment options reported in the literature with variable results. We review our experience with the vascularized-fibular osteocutaneous graft for these complex defects with a focus on surgical techniques and outcomes. © 2009 Wiley-Liss, Inc. Microsurgery, 2011.