Reconstructive options for oncologic posterior trunk defects

After oncological tumor resections at the back, large defects can remain that depending on the size and location may represent reconstructive challenges to plastic surgeons. Flap selection includes the entire armamentarium of coverage, including transposition flaps, perforator flaps, pedicled muscle flaps, and free flaps. Most defects can be closed and reconstructed with local or pedicled muscle flaps. In our hands, sufficient closure could be obtained with all techniques, except the latissimus dorsi turn-over flap. Thereupon, an algorithm for closure of posterior trunk defects related to the anatomical region is proposed

Negative impact of wound complications on oncologic outcome of soft tissue sarcomas of the chest wall

A link of complications with worse oncologic prognosis has been established for multiple malignancies, while the limited literature on soft-tissue sarcomas is inconclusive. The aim of this study was to examine risk factors and the oncologic impact of wound complications after curative resection of primary soft-tissue sarcomas of the chest wall. Patients with primary soft tissue sarcomas of the chest wall were identified. Groups with and without wound complications were compared by using univariate and multivariate analysis to identify risk factors. For patients with clear surgical margins (R0), univariate and multivariate analysis of factors associated with 5-year local recurrence free survival (LRFS), metastasis free survival (MFS), and disease specific survival (DSS) were performed. A total of 102 patients were included in the study. Wound complications occurred in 11 patients (10.8%) within 90 days. Cardiovascular morbidity and operation time represented independent risk factors for wound complications. In 94 patients with clear surgical margins, those with wound complications had an estimated 5-year LRFS of 30% versus 72.6% and a 5-year DSS of 58.3% versus 82.1%. Wound complications could be identified as an independent predictor for worse LRFS and DSS. Patients with a high risk of wound complications should be identified and strategies implemented to reduce surgical complications and possibly improve oncologic prognosis

An optimized low-pressure tourniquet murine hind limb ischemia reperfusion model

Acute ischemia reperfusion injury in skeletal muscle remains an important issue in several fields of regenerative medicine. Thus, a valid model is essential to gain deeper insights into pathophysiological relations and evaluate possible treatment options. While the vascular anatomy of mice regularly prevents sufficient vessel occlusion by invasive methods, there is a multitude of existing models to induce ischemia reperfusion injury without surgical procedures. Since there is no consensus on which model to prefer, this study aims to develop and evaluate a novel, optimized low-pressure tourniquet model. C57BL/6 mice underwent an ischemic procedure by either tourniquet or invasive artery clamping. A sham group served as control. With exception of the sham group, mice underwent 2 hours of ischemia followed by 4 hours of reperfusion. Groups were compared using microcirculatory and spectroscopic measurements, distinctions in tissue edema, histological and immunohistochemical analyses. Both procedures led to a significant decrease in tissue blood flow (- 97% vs. - 86%) and oxygenation (- 87% vs. - 75%) with a superiority of the low-pressure tourniquet. Tissue edema in the tourniquet cohort was significantly increased (+ 59%), while the increase in the clamping cohort was non-significant (+ 7%). Haematoxylin Eosin staining showed significantly more impaired muscle fibers in the tourniquet group (+ 77 p.p. vs. + 11 p.p.) and increased neutrophil infiltration/ROI (+ 51 vs. + 8). Immunofluorescence demonstrated an equal increase of p38 in both groups (7-fold vs. 8-fold), while the increase in apoptotic markers (Caspase-3, 3-Nitrotyrosine, 4-Hydroxynonenal) was significantly higher in the tourniquet group. The low-pressure tourniquet has been proven to produce reproducible and thus reliable ischemia reperfusion injury. In addition, significantly less force was needed than previously stated. It is therefore an important instrument for studying the pathophysiology of ischemia reperfusion injury and for the development of prophylactic as well as therapeutic interventions

Myostatin upregulation in patients in the chronic phase of severe burn injury leads to muscle cell catabolism

$\bf Background:$ Burn injury leads to a hypercatabolic response and ultimately muscle wasting with drastic implications for recovery of bodily functions, patient’s quality of life (QoL), and long-term survival. Several treatment options target the body’s initial stress response, but pharmacological approaches to specifically address muscle protein metabolism have only been poorly investigated. $\bf Objective:$ The aim of this study was to assess the role of myostatin and follistatin in burn injury and its possible implications in muscle wasting syndrome. $\bf Methods:$ We harvested serum from male patients within 48 h and again 9–12 months after severe burn injury (>20% of total body surface area). By means of myoblast cultures, immunohistochemistry, immunoblotting, and scratch assay, the role of myostatin and its implications in post-burn muscle metabolism and myoblast proliferation and differentiation was analyzed. $\bf Results:$ We were able to show increased proliferative and myogenic capacity, decreased myostatin, decreased SMAD 2/3, and elevated follistatin concentrations in human skeletal myoblast cultures with serum conditioned medium of patients in the acute phase of burn injury and conversely a reversed situation in patients in the chronic phase of burn injury. Thus, there is a biphasic response to burn trauma, initiated by an anabolic state and followed by long-term hypercatabolism. $\bf Conclusion:$ We conclude that the myostatin signaling pathway plays an important regulative role in burn-associated muscle wasting and that blockade of myostatin could prove to be a valuable treatment approach improving the rehabilitation process, QoL, and long-term survival after severe burn injury

Superior enhancement of cutaneous microcirculation due to "cyclic" application of a negative pressure wound therapy device in humans

$\bf Objectives:$ Despite a common utilization of "Negative Pressure Wound Therapy" (NPWT) Devices in a wide range of specialties, some of the basic mechanisms of action of the techniques are still on debate. Conflicting results from prior studies demonstrate our lack of understanding how wound-bed perfusion or cutaneous microcirculation is affected by NPWT. $\bf Methods:$ We conducted a prospective randomized study which included 45 healthy subjects to further investigate the acute effects of NPWT on cutaneous microcirculation underneath the applied dressing. Three modes of application, namely, continuous, intermittent, cyclic, were tested. Amongst others, measurements of elicited surface pressure and a comprehensive microcirculatory analysis were carried out by utilizing an O2C-device. For the detection of (systemic) remote effects, perfusion changes of the contra-lateral thigh were evaluated. $\bf Results:$ All three tested modes of application led to a significant ($\it p$ < 0.05) improvement in local tissue perfusion with an increased blood flow of max +151% and tissue oxygen saturation of +28.2% compared to baseline values. Surface pressure under the dressing significantly increased up to 29.29 mmHg due to the activation of the NPWT device. Continuous, intermittent, and cyclic application of negative pressure were accurately sensed by participants, resulting in reported pain values that mirrored the different levels of applied suction. Although the cyclic application mode showed the most pronounced effects regarding microcirculatory changes, no statistical significance between groups was observed. $\bf Conclusion:$ We could demonstrate a significant improvement of cutaneous microcirculation under an applied NPWT dressing with favorable effects due to cyclic mode of application. An increased surface pressure leads to a better venous drainage of the tissue, which was shown to increase arterial inflow with a consecutive improvement of oxygen supply. Further research is warranted to evaluate our findings regarding wound bed perfusion in the clinical field with respect to formation of granulation tissue and wound healing

Inhibition of GDF8 (Myostatin) accelerates bone regeneration in diabetes mellitus type 2

Metabolic diseases like diabetes mellitus cause bone healing deficiencies. We found significant impairment of bone regeneration, osteogenic differentiation and proliferation in diabetic bone. Moreover recent studies suggest a highly underestimated importance of GDF8 (Myostatin) in bone metabolism. Our goal was to analyze the role of GDF8 as a regulator of osteogenic differentiation, proliferation and bone regeneration. We used a murine tibial defect model in diabetic ($Lepr^{db-/-}$) mice. Myostatin-Inhibitor Follistatin was administered in tibial bony defects of diabetic mice. By means of histology, immunohistochemistry and QRT-PC osteogenesis, differentiation and proliferation were analyzed. Application of Myostatin-inhibitor showed a significant improvement in diabetic bone regeneration compared to the control group (6.5 fold, p < 0.001). Immunohistochemistry revealed a significantly higher proliferation (7.7 fold, p = 0.009), osteogenic differentiation (Runx-2: 3.7 fold, p = 0.011, ALP: 9.3 fold, p < 0.001) and calcification (4.9 fold, p = 0.024) in Follistatin treated diabetic animals. Therapeutical application of Follistatin, known for the importance in muscle diseases, plays an important role in bone metabolism. Diabetic bone revealed an overexpression of the catabolic protein Myostatin. Antagonization of Myostatin in diabetic animals leads to a restoration of the impaired bone regeneration and represents a promising therapeutic option

Autologous vs. implant-based breast reconstruction after skin- and nipple-sparing mastectomy

$\bf Introduction:$ Autologous (ABR) and implant-based breast reconstruction (IBR) represent the most common procedures after skin- and nipple-sparing mastectomy. This cross-sectional study is a comprehensive analysis of ABR and IBR considering surgical and patient-reported outcomes. $\textbf {Patients and methods:}$ Eligible patients underwent breast reconstruction (ABR and IBR) after skin- and nipple-sparing mastectomy between January 2014 and December 2020. Outcome parameters included quality of life (European Organisation for Research and Treatment of Cancer - EORTC - QLQ30, BR23, Breast-Q, CES-D), complication rates, aesthetic result, and breast sensitivity. $\bf Results:$ 108 patients participated in the study (IBR: $\it n$ = 72, age 48.9 $\pm$ 9.9 years; ABR: $\it n$ = 36, age: 46.6 $\pm$ 7.3 years). Mean follow-up was 27.1 $\pm$ 9.3 (IBR) and 34.9 $\pm$ 20.5 (ABR), respectively. IBR patients suffered significantly more often from major complications (30.6% vs. 8.3%; $\it p$ = 0.01), while ABR patients underwent secondary procedures significantly more often to improve the aesthetic result (55.6% vs. 29.2%, $\it p$ = 0.004). Unilateral reconstructions revealed superior aesthetic results in ABR (n.s.), while in bilateral reconstruction IBR tended to score higher (n.s.). Scar evaluation resulted in a better result of IBR in both categories ($\it p$ < 0.01). Breast sensitivity was severely impaired in both groups. The Breast-Q revealed a significantly higher "patient satisfaction with breast" after ABR ($\it p$ = 0.033), while the other QoL-tests and subscales showed no significant differences between the two procedures. $\bf Conclusion:$ ABR is associated with a higher patient satisfaction despite the high probability of secondary procedures to improve the aesthetic outcome, whereas IBR-patients suffer more often from major complications. Furthermore, the laterality of reconstruction should be included in the individual decision-making process

Inhibition of pathological increased matrix metalloproteinase (MMP) activity for improvement of bone regeneration in diabetes

Patients with diabetes suffer from poor fracture healing. Molecular reasons are not fully understood and our previous gene expression microarray analyses of regenerating bones from mice with type 2 diabetes (db$^{−}$/db$^{−}$) revealed accelerated activation of pathways concerning matrix metalloproteases (MMPs). Thus, we picked out the pathological MMP acceleration as a target for profound gene expression analyses and additional therapeutic intervention in the present study. In the first part, gene expression of ECM degrading proteinases and inhibitors was investigated three and seven days postoperatively. $\it Mmp3$, $\it Mmp9$, $\it Mmp13$ and gene expression of MMP inhibitor $\it Timp2$ was significantly higher in regenerating bone fractures of db$^{−}$/db$^{−}$ compared to wild type animals. $\it Timp1$ and metalloproteinase $\it AdamTS4$ showed no differences. In the second part, we locally applied a single dose (1 $\mu$L of 5 $\mu$M solution) of the broad-spectrum molecular MMP inhibitor Marimastat on tibial defects in db$^{−}$/db$^{−}$. We performed immunohistochemical and histological stainings seven days post operation. Impaired bone healing, collagen content, angiogenesis, and osteoclast invasion in db$^{−}$/db$^{−}$ were restored significantly by application of Marimastat compared to PBS controls ($\it n$ = 7/group). Hence, local intervention of bone defects by the molecular MMP inhibitor Marimastat might be an alternative therapeutic intervention for bone healing in diabetes

Posttraumatic lymphedema after open fractures of the lower extremity

Secondary lymphedema is a very common clinical issue with millions of patients suffering from pain, recurrent skin infections, and the constant need for a decongestive therapy. Well-established as a consequence of oncologic procedures, secondary lymphedema is also a well-known phenomenon after trauma. However, precise epidemiological data of lymphedema progress upon severe extremity injuries are still missing. In the present work, we analyzed a patient cohort of 94 individuals who suffered open fractures of the lower extremity and soft tissue injury, of 2nd and 3rd grade according to Tscherne classification, between 2013 and 2019. Typical symptoms of lymphedema have been obtained via interviews and patient medical records in a retrospective cohort analysis. Of all patients, 55% showed symptoms of secondary lymphedema and 14% reported recurrent skin infections, indicating severe lymphedema. Furthermore, comparing patients with and without lymphedema, additional parameters, such as obesity, total number of surgeries, infections, and compartment syndrome, related to lymphedema progress could be identified. According to these data, posttraumatic secondary lymphedema has a highly underestimated clinical prevalence. Further prospective studies are needed to validate this first observation and to identify high-risk groups in order to improve patient's health care

Alterations in pectoralis muscle cell characteristics after radiation of the human breast insitu\textit in situ

The life-time risk of being diagnosed with breast cancer is ~12%, hence breast cancer is by far the most common cancer among women. The multimodal treatment concept of breast cancer often intends radiation. The utilized ionizing radiation leads changes in the tissue resulting in tissue damage due to an alteration of molecular factors. The goal of this study was to identify the role of muscle-catabolic proteins after radiation of human pectoralis major muscles in situ. Tissue of the pectoralis major muscle was collected in 12 breast cancer patients after radiation (maximum 3 years after radiation) undergoing a deep inferior epigastric perforator free-flap breast reconstruction. At the same time, an intraindividual comparison to rectus abdominis muscle was carried out upon free-flap elevation. Immunological properties, cell proliferation, differentiation as well as the expression profile of the muscle tissue were investigated through immunohistological reactions, a DNA-microarray and histology. We found significantly increased neutrophil immigration in the radiated muscle tissue. At the same time, proteins responsible for muscular atrophy and apoptosis were significantly elevated in immunohistochemistry. A DNA microarray detected immunological upregulation and myo-differentiative disorders in radiated muscle tissue. This novel study investigating catabolism in radiated muscle in situ can serve as a basis for the treatment of radiation-accompanied muscle disorders