Diabetic foot resurfacing using microvascular tissue transfer from lateral thoracic region.

AIMS: Diabetic foot ulcer is a major complication of diabetes mellitus and amputation is often needed. Since mortality rate after amputation is comparatively high, saving diabetic foot is required not only for preserving function and life quality, but also for decreasing mortality rate. This study was designed to analyse experience of limb salvage in patients with diabetic foot using free flaps from the lateral thoracic region over a 10-year period. MATERIALS AND METHODS: Between 2009 and 2018, 297 cases of diabetic foot underwent surgical procedures. We analysed the 83 cases who underwent free flap from lateral thoracic region. Patient data were reviewed retrospectively. RESULTS: A total of 83 patients, 56 of them males, were included in this study. Age of patients ranged from 27 to 80 years. Twenty patients underwent percutaneous transluminal angioplasty procedures. The latissimus dorsi muscle sparing technique was used in 7 cases. A thoracodorsal artery perforator flap was used in 68 cases. A thoracodorsal artery perforator chimaeric flap was performed in 8 cases. The flap survival rate was 98.8% and the limb salvage rate was 96.4%. The mean follow-up was 6.5 years. During follow-up 14 patients suffered recurrence of foot ulcers. CONCLUSIONS: Ten-year experience of using flaps from the lateral thoracic region revealed superior outcomes in terms of flap survival and limb saving compared to those in a recent meta-analysis and other reports. Long vascular pedicle technique and the chimaeric technique might be the alternative methods for multiple or vascular insufficient diabetic foot defects.

Reconstruction of diabetic lower leg and foot soft tissue defects using thoracodorsal artery perforator chimeric flaps.

BACKGROUND: Reconstruction of complicated diabetic lower leg and foot defects involving multiple tissue components remains a challenge. The purpose of this report is to introduce thoracodorsal artery perforator (TDAP) chimeric flaps for reconstructing diabetic lower leg and foot soft tissue defects. PATIENTS AND METHODS: Between April 2010 and August 2016, 17 patients with multiple diabetic lower leg and foot defects underwent reconstruction with TDAP chimeric flaps. Nine were women and the mean age of the patients was 57.7 years (range 35-73 years). One patient had 3 separate defects, 14 patients had 2 separate defects, and 2 patients had defects with dead space. The size of the defects ranged from 5 × 3 cm to 20 × 10 cm. RESULTS: Fifteen patients received TDAP chimeric flaps with two components (skin and muscle components), and two received three components (skin, latissimus dorsi (LD), and serratus anterior [SA] components). The skin paddle ranged from 10 × 3 cm to 25 × 14 cm. The LD components ranged from 3 × 5 cm to 20 × 10 cm and SA components ranged from 5 × 2 cm to 8 × 7 cm. All flaps survived except for partial loss of one muscle component. Four patients suffered postoperative complications including wound disruption and infection, all of which healed conservatively. The mean follow-up was 31.3 months (range 8-60 months). Fifteen patients were able to walk, one patient walked with walker, and one patient who had amputation due to Charcot joint infection walked with prosthesis. CONCLUSIONS: The TDAP chimeric flap may be another option for the complicated and complex wound coverage required to reconstruct diabetic lower leg and foot soft tissue defects.

Microwave sintering and in vitro study of defect-free stable porous multilayered HAp-ZrO2 artificial bone scaffold.

Continuously porous hydroxyapatite (HAp)/t-ZrO2 composites containing concentric laminated frames and microchanneled bodies were fabricated by an extrusion process. To investigate the mechanical properties of HAp/t-ZrO2 composites, the porous composites were sintered at different temperatures using a microwave furnace. The microstructure was designed to imitate that of natural bone, particularly small bone, with both cortical and spongy bone sections. Each microchannel was separated by alternating lamina of HAp, HAp-(t-ZrO2) and t-ZrO2. HAp and ZrO2 phases existed on the surface of the microchannel and the core zone to increase the biocompatibility and mechanical properties of the HAp-ZrO2 artificial bone. The sintering behavior was evaluated and the optimum sintering temperature was found to be 1400 °C, which produced a stable scaffold. The material characteristics, such as the microstructure, crystal structure and compressive strength, were evaluated in detail for different sintering temperatures. A detailed in vitro study was carried out using MTT assay, western blot analysis, gene expression by polymerase chain reaction and laser confocal image analysis of cell proliferation. The results confirmed that HAp-ZrO2 performs as an artificial bone, showing excellent cell growth, attachment and proliferation behavior using osteoblast-like MG63 cells.

Collagen and bone morphogenetic protein-2 functionalized hydroxyapatite scaffolds induce osteogenic differentiation in human adipose-derived stem cells.

Surface modification is one important way to fabricate successful biocompatible materials in bone tissue engineering. Hydroxyapatite (HAp) materials have received considerable attention as suitable bioceramics for manufacturing osseous implants because of their similarity to bone mineral in terms of chemical composition. In this study, the surface of porous HAp scaffold was modified by collagen treatment and bone morphogenetic protein-2 (BMP-2) conjugation. The surface modification did not affect the HAp scaffold's bulk properties. No significant difference in compressive strength was found among different scaffolds, with HAp, collagen modified HAp, and collagen-BMP-2-functionalized HAp having compressive strengths of 45.8 ± 3.12, 51.2 ± 4.09, and 50.7 ± 3.98 MPa, respectively. In vitro studies were performed to compare adhesion and osteogenic differentiation between human adipose-derived stem cells (hADSCs) with modified surfaces and those unmodified HAp surfaces. Collagen or BMP-2 alone was insufficient and that both collagen and BMP-2 are necessary to get the desired results. The findings suggest the possibility of using three-dimensional HAp scaffold treated with gold-standard collagen coating and highly researched BMP-2 growth factor as a platform to deliver hADSCs. Results of this study could be used to develop treatment strategy for regenerating completely transected models using more synergistic approaches.

Lower Extremity Salvage with Thoracodorsal Artery Perforator Free Flap in Condition of Symmetrical Peripheral Gangrene.

Symmetrical peripheral gangrene (SPG) is rare but devastating complication which is characterized by symmetrical ischemic change of the distal extremities. In this report, we describe our management protocol for SPG, focusing on surgical approaches. Between January 2007 and February 2016, 10 thoracodorsal artery perforator (TDAP) free flaps were performed in 6 patients with SPG. Three patients were male and mean age was 56 (range, 44-69) years. All the patients were in shock. The causes of shock were sepsis in 4 cases, respiratory arrest in 1 case, and hypovolemia in 1 case. Eight transmetatarsal amputations and 2 Lisfranc amputations were performed. Flap sizes ranged from 7 × 11 cm to 25 × 15 cm. There were 3 cases of partial necrosis of the flap: two healed conservatively with dressings and one required skin graft. Three of the patients were later able to walk independently at Functional Ambulation Classification (FAC) level 6, one patient could walk independently on level surfaces at FAC level 5, and 2 could walk independently using walking aids, classified at FAC level 4. The average follow-up period was 18 (range, 6-54) months. In patients with SPG, minimal bone amputation and foot salvage with TDAP flaps were successful. Separate reconstruction of bone and soft tissue had good outcomes.

Phosphonate-chitosan functionalization of a multi-channel hydroxyapatite scaffold for interfacial implant-bone tissue integration.

Nonunion associated with long bone defects continues to be highly researched both experimentally and clinically. A porous hydroxyapatite (HAp) scaffold has been recognized as a bone repair and substitute material clinically, but its use in segmental bone defects has been limited by poor integration and stability, as a consequence of scaffold strength unmatched with the native bone. Herein, we designed a multi-channel HAp-based scaffold for application in segmental bone defects, with a specific geometry and design. It possesses the required porosity for bone tissue regeneration with sufficient mechanical properties. We also developed a surface functionalization/modification method with the goal of early scaffold integration and stability. Initial functionalization with poly(vinyl phosphonic acid), PVPA, allowed simple attachment of a chitosan polymeric layer. The modification improved the biocompatibility of the scaffold and attachment of rat bone marrow-derived mesenchymal stem cells (rBMSC) in vitro. The modification also served as a buffer between the implant scaffold and bone tissue. Significant improvement in the integration behavior with better interlocking of the scaffold to bone tissue was observed for the modified scaffolds implanted in rabbit tibiae. The modified HAp scaffolds exhibited early interfacial implant-bone tissue integration with enhanced new bone formation and high potential for use in segmental bone defects.

Fabrication of porous hydroxyapatite scaffolds as artificial bone preform and its biocompatibility evaluation.

In this study, a novel porous hydroxyapatite scaffold was designed and fabricated to imitate natural bone through a multipass extrusion process. The conceptual design manifested unidirectional microchannels at the exterior part of the scaffold to facilitate rapid biomineralization and a central canal that houses the bone marrow. External and internal fissures were minimized during microwave sintering at 1,100 °C. No deformation was noted, and a mechanically stable scaffold was fabricated. Detailed microstructure of the fabricated artificial bone was examined by scanning electron microscope and X-ray diffractometer, and material properties like compressive strength were evaluated. The initial biocompatibility was examined by the cell proliferation of MG-63 osteoblast-like cells using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Preliminary in vivo investigation in a rabbit model after 4 weeks and 8 weeks of implantation showed full osteointegration of the scaffold with the native tissue, and formation of bone tissue within the pore network, as examined by microcomputed tomography analyses and histological staining. Osteon-like bone microarchitecture was observed along the unidirectional channel with microblood vessels. These confirm a biomimetic regeneration model in the implanted bone scaffold, which can be used as an artificial alternative for damaged bone.