A vascularized in vivo melanoma model suitable for metastasis research of different tumor stages using fundamentally different bioinks

Although 2D cancer models have been the standard for drug development, they don't resemble in vivo properties adequately. 3D models can potentially overcome this. Bioprinting is a promising technique for more refined models to investigate central processes in tumor development such as proliferation, dormancy or metastasis. We aimed to analyze bioinks, which could mimic these different tumor stages in a cast vascularized arteriovenous loop melanoma model in vivo. It has the advantage to be a closed system with a defined microenvironment, supplied only with one vessel-ideal for metastasis research. Tested bioinks showed significant differences in composition, printability, stiffness and microscopic pore structure, which led to different tumor stages (Matrigel and Alg/HA/Gel for progression, Cellink Bioink for dormancy) and resulted in different primary tumor growth (Matrigel significantly higher than Cellink Bioink). Light-sheet fluorescence microscopy revealed differences in vascularization and hemorrhages with no additional vessels found in Cellink Bioink. Histologically, typical human melanoma with different stages was demonstrated. HMB-45-positive tumors in progression inks were infiltrated by macrophages (CD163), highly proliferative (Ki67) and metastatic (MITF/BRN2, ATX, MMP3). Stainings of lymph nodes revealed metastases even without significant primary tumor growth in Cellink Bioink. This model can be used to study tumor pathology and metastasis of different tumor stages and therapies.

Transcription factor activating enhancer-binding protein 2ε (AP2ε) modulates phenotypic plasticity and progression of malignant melanoma

Malignant melanoma, the most aggressive form of skin cancer, is often incurable once metastatic dissemination of cancer cells to distant organs has occurred. We investigated the role of Transcription Factor Activating Enhancer-Binding Protein 2ε (AP2ε) in the progression of metastatic melanoma. Here, we observed that AP2ε is a potent activator of metastasis and newly revealed AP2ε to be an important player in melanoma plasticity. High levels of AP2ε lead to worsened prognosis of melanoma patients. Using a transgenic melanoma mouse model with a specific loss of AP2ε expression, we confirmed the impact of AP2ε to modulate the dynamic switch from a migratory to a proliferative phenotype. AP2ε deficient melanoma cells show a severely reduced migratory potential in vitro and reduced metastatic behavior in vivo. Consistently, we revealed increased activity of AP2ε in quiescent and migratory cells compared to heterogeneously proliferating cells in bioprinted 3D models. In conclusion, these findings disclose a yet-unknown role of AP2ε in maintaining plasticity and migration in malignant melanoma cells.

The Impact of Technical Innovations and Donor-Site Mesh Repair on Autologous Abdominal-Based Breast Reconstruction-A Retrospective Analysis

Background: The aim of this study was to examine the potential benefit that may be achieved through the introduction of technical innovations and the incorporation of mesh for fascial donor site closure in uni- and bilateral autologous breast reconstruction with abdominal tissue. Methods: A retrospective single-center review of all breast reconstructions with a DIEP or MS-TRAM flap between January 2004 and December 2019 was performed. Donor and recipient site complications and operation times were evaluated before and after the implementation of coupler anastomoses, preoperative computed tomography angiography (CTA), indocyanine green (ICG) angiography, and the inclusion of mesh in donor site repair. Results: A total of 396 patients were included, accounting for 447 flaps. Operation time was significantly shorter in unilateral reconstructions after the implementation of CTA (p < 0.0001). ICG angiography significantly reduced the rates of partial flap loss (p = 0.02) and wound healing disorders (p = 0.02). For unilateral reconstructions, abdominal bulging or hernia was observed more often in MS1-TRAM flaps without synthetic mesh repair (p = 0.001), whereas conservatively treated seroma developed more frequently after mesh implantation (p = 0.03). Conclusions: Recent technological advancements developed over the past few decades have made a substantial impact on decreasing surgical duration and enhancing procedure safety.

Quick and safe: why a k-wire-extension-block-fixation of a bony mallet finger is the favoured treatment

INTRODUCTION

Mallet fingers are the most common tendon injuries of the hand. Bony avulsion distal finger extensor tendon ruptures causing a mallet finger require special attention and management. In this monocentral study, we analyzed the clinical and individual outcomes succeeding minimal invasive k-wire extension block treatment of bony mallet fingers.

MATERIALS AND METHODS

In a retrospective study, we sent a self-designed template and a QUICK-DASH score questionnaire to all patients, who were treated because of a bony mallet finger between 2009 and 2022 and fulfilled the inclusion criteria. A total of 244 requests were sent out. 72 (29.5%) patients participated in the study. Forty-five men and twenty-seven women were included.

RESULTS

98.7% (n = 75) of the cases were successfully treated. Patients were highly satisfied with the treatment (median 8.0; SD ± 2.9; range 1.0-10.0). Based on the QUICK-DASH score, all patients showed no difficulties in daily life. The extent of avulsion did not influence the outcome.

CONCLUSION

We conclude that the minimally invasive treatment of a bony mallet finger should be offered to every patient, because it is safe, fast, and reliable. Thus, we propose to perform extension-block pinning independently of the articular area.

Schwann Cells Do Not Promote Myogenic Differentiation in the EPI Loop Model

In skeletal muscle tissue engineering, innervation and vascularization play an essential role in the establishment of functional skeletal muscle. For adequate three-dimensional assembly, biocompatible aligned nanofibers are beneficial as matrices for cell seeding. The aim of this study was to analyze the impact of Schwann cells (SC) on myoblast (Mb) and adipogenic mesenchymal stromal cell (ADSC) cocultures on poly-ɛ-caprolactone (PCL)-collagen I-nanofibers in vivo. Human Mb/ADSC cocultures, as well as Mb/ADSC/SC cocultures, were seeded onto PCL-collagen I-nanofiber scaffolds and implanted into the innervated arteriovenous loop model (EPI loop model) of immunodeficient rats for 4 weeks. Histological staining and gene expression were used to compare their capacity for vascularization, immunological response, myogenic differentiation, and innervation. After 4 weeks, both Mb/ADSC and Mb/ADSC/SC coculture systems showed similar amounts and distribution of vascularization, as well as immunological activity. Myogenic differentiation could be observed in both groups through histological staining (desmin, myosin heavy chain) and gene expression (MYOD, MYH3, ACTA1) without significant difference between groups. Expression of CHRNB and LAMB2 also implied neuromuscular junction formation. Our study suggests that the addition of SC did not significantly impact myogenesis and innervation in this model. The implanted motor nerve branch may have played a more significant role than the presence of SC.

Variation in cartilage T2 and T2* mapping of the wrist: a comparison between 3- and 7-T MRI

BACKGROUND

To analyze regional variations in T2 and T2* relaxation times in wrist joint cartilage and the triangular fibrocartilage complex (TFCC) at 3 and 7 T and to compare values between field strengths.

METHODS

Twenty-five healthy controls and 25 patients with chronic wrist pain were examined at 3 and 7 T on the same day using T2- and T2*-weighted sequences. Six different regions of interest (ROIs) were evaluated for cartilage and 3 ROIs were evaluated at the TFCC based on manual segmentation. Paired t-tests were used to compare T2 and T2* values between field strengths and between different ROIs. Spearman's rank correlation was calculated to assess correlations between T2 and T2* time values at 3 and 7 T.

RESULTS

T2 and T2* time values of the cartilage differed significantly between 3 and 7 T for all ROIs (p ≤ 0.045), with one exception: at the distal lunate, no significant differences in T2 values were observed between field strengths. T2* values differed significantly between 3 and 7 T for all ROIs of the TFCC (p ≤ 0.001). Spearman's rank correlation between 3 and 7 T ranged from 0.03 to 0.62 for T2 values and from 0.01 to 0.48 for T2* values. T2 and T2* values for cartilage varied across anatomic locations in healthy controls at both 3 and 7 T.

CONCLUSION

Quantitative results of T2 and T2* mapping at the wrist differ between field strengths, with poor correlation between 3 and 7 T. Local variations in cartilage T2 and T2* values are observed in healthy individuals.

RELEVANCE STATEMENT

T2 and T2* mapping are feasible for compositional imaging of the TFCC and the cartilage at the wrist at both 3 and 7 T, but the clinical interpretation remains challenging due to differences between field strengths and variations between anatomic locations.

KEY POINTS

•Field strength and anatomic locations influence T2 and T2* values at the wrist. •T2 and T2* values have a poor correlation between 3 and 7 T. •Local reference values are needed for each anatomic location for reliable interpretation.

The Influence of Different Irradiation Regimens on Inflammation and Vascularization in a Random-Pattern Flap Model

BACKGROUND

Irradiation plays an important role in the oncological treatment of various tumor entities. The aim of the study was to investigate the influence of different irradiation regimens on random-pattern flaps at the molecular and histopathological levels.

METHODS

Twenty-five rats underwent harvesting of bilateral random-pattern fasciocutaneous flaps. The right flaps received irradiation, while the left flaps served as non-irradiated intraindividual controls. Five rats served as a non-irradiated control group. Four different irradiation regimens with give rats each were tested: 20 Gy postoperatively, 3 × 12 Gy postoperatively, 20 Gy preoperatively, and 3 × 12 Gy preoperatively. Two weeks after surgery, HE staining and immunohistochemical staining for CD68 and ERG, as well as PCR analysis to detect Interleukin 6, HIF-1α, and VEGF, were performed.

RESULTS

A postoperative cumulative higher dose of irradiation appeared to result in an increase in necrosis, especially in the superficial layers of the flap compared to preoperative or single-stage irradiation. In addition, we observed increased expression of VEGF and HIF-1α in all irradiation groups.

CONCLUSION

Even though no statistically significant differences were found between the different groups, there was a tendency for fractional postoperative irradiation with a higher total dose to have a more harmful effect compared to preoperative or single-dose irradiation.

Prospective analysis of grip strength and load distribution after surgical treatment of common diseases of the hand with novel's manugraphy® system

BACKGROUND

Carpal tunnel syndrome, A1 annular pulley stenosis and Dupuytren's contracture are among the most common conditions of the hand. In this study, we investigated the impact of surgical procedure on hand grip strength and high-resolution spatial load distribution in individuals suffering from those diseases over a follow-up period of one year.

MATERIALS AND METHODS

In this prospective study, data of 9 patients with carpal tunnel syndrome, 12 patients with A1 annular pulley stenosis and 7 patients with Dupuytren's contracture were evaluated. Only patients with unilateral disease were included providing the contralateral hand as an intra-individual control. Grip strength was measured with cylindrical instruments in two different sizes with respect to the hand size of the patients. Maximum and average values of grip strength as well as spatial load distribution in each finger, thenar, hypothenar and palm were analyzed. Data of the affected patients were collected preoperatively and 6 weeks, 6 months and 1 year postoperatively. Grip strength and spatial load distribution were compared preoperatively to postoperatively. In addition, DASH score, Levine score, 2-point discrimination and degree of flexion contracture were assessed.

RESULTS

The patients with A1 annular pulley stenosis showed a significant increase in grip strength 6 months and one year postoperatively. Patients with carpal tunnel syndrome and Dupuytren's contracture showed no significant difference in grip strength over the course of time. An increase in the percentual grip strength of the thenar in patients with carpal tunnel disease and within the affected finger in A1 annular pulley stenosis was observed over the course of time. The DASH score was significantly lower in all patient cohorts one year postoperatively.

CONCLUSION

Surgical procedure in carpal tunnel syndrome, A1 annular ligament stenosis and Dupuytren's contracture improves the functionality of the hand in everyday life. Some areas of the hand seem to compensate other weaker areas in grip strength.

Interdisciplinary Treatment of Malignant Chest Wall Tumors

BACKGROUND

Chest wall resections for malignant chest wall tumors (MCWTs), particularly those with full-thickness chest wall involvement requiring reconstruction, present a therapeutic challenge for thoracic and plastic reconstructive surgeons. The purpose of this study was to review our experience with chest wall resection for primary and metastatic MCWTs, with a focus on perioperative outcomes and postoperative overall survival (OS).

METHODS

All patients who underwent surgical resection for primary and secondary MCWTs at our single institution between 2000 and 2019 were retrospectively analyzed.

RESULTS

A total of 42 patients (25 male, median age 60 years) operated upon with curative (n = 37, 88.1%) or palliative (n = 5, 11.9%) intent were reviewed. Some 33 (78%) MCWTs were of secondary origin. Chest wall reconstruction was required in 40 (95%) cases. A total of 13 (31%) patients had postoperative complications and one (2.3%) died perioperatively. The 5-year postoperative overall survival rate was 51.9%. The postoperative 5-year survival rate of 42.6% in patients with secondary MCWTs was significantly lower compared to the figure of 87.5% in patients with primary MCWTs.

CONCLUSIONS

In well-selected patients, chest wall resections for primary and secondary MCWTs are feasible and associated with good perioperative outcomes. For secondary MCWTs, surgery can also be performed with palliative intent.

Comparison of the Behavior of 3D-Printed Endothelial Cells in Different Bioinks

Biomaterials with characteristics similar to extracellular matrix and with suitable bioprinting properties are essential for vascular tissue engineering. In search for suitable biomaterials, this study investigated the three hydrogels alginate/hyaluronic acid/gelatin (Alg/HA/Gel), pre-crosslinked alginate di-aldehyde with gelatin (ADA-GEL), and gelatin methacryloyl (GelMA) with respect to their mechanical properties and to the survival, migration, and proliferation of human umbilical vein endothelial cells (HUVECs). In addition, the behavior of HUVECs was compared with their behavior in Matrigel. For this purpose, HUVECs were mixed with the inks both as single cells and as cell spheroids and printed using extrusion-based bioprinting. Good printability with shape fidelity was determined for all inks. The rheological measurements demonstrated the gelling consistency of the inks and shear-thinning behavior. Different Young's moduli of the hydrogels were determined. However, all measured values where within the range defined in the literature, leading to migration and sprouting, as well as reconciling migration with adhesion. Cell survival and proliferation in ADA-GEL and GelMA hydrogels were demonstrated for 14 days. In the Alg/HA/Gel bioink, cell death occurred within 7 days for single cells. Sprouting and migration of the HUVEC spheroids were observed in ADA-GEL and GelMA. Similar behavior of the spheroids was seen in Matrigel. In contrast, the spheroids in the Alg/HA/Gel ink died over the time studied. It has been shown that Alg/HA/Gel does not provide a good environment for long-term survival of HUVECs. In conclusion, ADA-GEL and GelMA are promising inks for vascular tissue engineering.

Myogenic differentiation of human myoblasts and Mesenchymal stromal cells under GDF11 on NPoly-ɛ-caprolactone-collagen I-Polyethylene-nanofibers

BACKGROUND

For the purpose of skeletal muscle engineering, primary myoblasts (Mb) and adipogenic mesenchymal stem cells (ADSC) can be co-cultured and myogenically differentiated. Electrospun composite nanofiber scaffolds represent suitable matrices for tissue engineering of skeletal muscle, combining both biocompatibility and stability Although growth differentiation factor 11 (GDF11) has been proposed as a rejuvenating circulating factor, restoring skeletal muscle function in aging mice, some studies have also described a harming effect of GDF11. Therefore, the aim of the study was to analyze the effect of GDF11 on co-cultures of Mb and ADSC on poly-ε-caprolactone (PCL)-collagen I-polyethylene oxide (PEO)-nanofibers.

RESULTS

Human Mb were co-cultured with ADSC two-dimensionally (2D) as monolayers or three-dimensionally (3D) on aligned PCL-collagen I-PEO-nanofibers. Differentiation media were either serum-free with or without GDF11, or serum containing as in a conventional differentiation medium. Cell viability was higher after conventional myogenic differentiation compared to serum-free and serum-free + GDF11 differentiation as was creatine kinase activity. Immunofluorescence staining showed myosine heavy chain expression in all groups after 28 days of differentiation without any clear evidence of more or less pronounced expression in either group. Gene expression of myosine heavy chain (MYH2) increased after serum-free + GDF11 stimulation compared to serum-free stimulation alone.

CONCLUSIONS

This is the first study analyzing the effect of GDF11 on myogenic differentiation of Mb and ADSC co-cultures under serum-free conditions. The results of this study show that PCL-collagen I-PEO-nanofibers represent a suitable matrix for 3D myogenic differentiation of Mb and ADSC. In this context, GDF11 seems to promote myogenic differentiation of Mb and ADSC co-cultures compared to serum-free differentiation without any evidence of a harming effect.

PIK3CA mutation testing as a valuable molecular surrogate for lipomatosis of the median nerve: clinicopathological and molecular analysis of six cases

Lipomatosis of peripheral nerves (LPN, also known as fibrolipomatous or lipofibromatous hamartoma of peripheral nerves) is a very rare, benign, intraneural, tumorous lesion that predominantly involves the median nerve but may rarely affect any peripheral nerve. Recently, PIK3CA mutations have been reported in macrodactyly, a rare condition related to LPN, and in other localized lipomatous overgrowth syndromes. In this retrospective study, we report 6 cases of FPN involving the median nerve (4 of them identified among 570 patients with carpal tunnel syndrome who underwent surgical decompression at our center from 2012 to 2022 and two seen in consultation by one of the authors). All cases were diagnosed via biopsy or resection supplemented by MRI. Patients were 4 males and 2 females aged 23 to 60 years (mean 38 years). One patient with bilateral lesions had in addition extensive angiomatosis of the paravertebral region. Histological examination showed an abnormal amount of mature fatty tissue containing disordered fibrous bands, entrapping normal-looking nerve fibers with prominent perineurial and endoneurial fibrosis. Genetic analysis using snapshot assay constructed to detect hotspots mutations in PIK3CA revealed similar PIK3CA mutations (p.H1047R; c.3140A>G) in 5/6 cases (83.3%). Our study represents a further contribution to the literature on LPN and highlights the diagnostic value of PIK3CA mutation testing as surrogate tool in equivocal cases and in those lesions without associated macrodactyly, especially as the biopsy findings of this lesion are essentially nonspecific.

Special Issue "Plastic and Reconstructive Surgery in Personalized Medicine"

With an ever-growing knowledge in various disciplines of medicine and with rapidly evolving new techniques and operative methods in plastic surgery, it is obvious that it becomes more and more difficult to keep up with all the developments in this field at any time [...].

Interdisciplinary Surgical Therapy of Extremity Soft-Tissue Sarcomas: A Personalized Resection and Reconstruction Algorithm

Soft-tissue sarcomas (STS) are rare, but potentially life-threatening malignancies. STS can occur anywhere in the human body with the limbs being the most common site. Referral to a specialized sarcoma center is crucial to guarantee prompt and appropriate treatment. STS treatment strategies should be discussed in an interdisciplinary tumor board to involve expertise from all available resources, including an experienced reconstructive surgeon for an optimal outcome. In many cases, extensive resection is needed to achieve R0 resection, resulting in large defects after surgery. Hence, an evaluation of whether plastic reconstruction might be required is mandatory to avoid complications due to insufficient primary wound closure. In this retrospective observational study, we present data of patients with extremity STS treated at the Sarcoma Center, University Hospital Erlangen, in 2021. We found that complications were more frequent in patients who received secondary flap reconstruction after insufficient primary wound closure compared to patients who received primary flap reconstruction. Additionally, we propose an algorithm for an interdisciplinary surgical therapy of soft-tissue sarcomas regarding resection and reconstruction and present two problematic cases to emphasize the complexity of surgical sarcoma therapy.

Corrigendum: Does indocyanine green fluorescence angiography impact the intraoperative choice of procedure in free vascularized medial femoral condyle grafting for scaphoid non-unions?

[This corrects the article DOI: 10.3389/fsurg.2022.962450.].

Clinical Application of Ultrahigh-Field-Strength Wrist MRI: A Multireader 3-T and 7-T Comparison Study

Background Ultrahigh-field-strength MRI at 7 T may permit superior visualization of noninflammatory wrist pathologic conditions, particularly due to its high signal-to-noise ratio compared with the clinical standard of 3 T, but direct comparison studies are lacking. Purpose To compare the subjective image quality of 3-T and 7-T ultrahigh-field-strength wrist MRI through semiquantitative scoring of multiple joint tissues in a multireader study. Materials and Methods In this prospective study, healthy controls and participants with chronic wrist pain underwent 3-T and 7-T MRI (coronal T1-weighted turbo spin-echo [TSE], coronal fat-suppressed proton-density [PD]-weighted TSE, transversal T2-weighted TSE) on the same day, from July 2018 to June 2019. Images were scored by seven musculoskeletal radiologists. The overall image quality, presence of artifacts, homogeneity of fat suppression, and visualization of cartilage, the triangular fibrocartilage complex (TFCC), and scapholunate and lunotriquetral ligaments were semiquantitatively assessed. Pairwise differences between 3 T and 7 T were assessed using the Wilcoxon signed-rank test. Interreader reliability was determined using the Fleiss kappa. Results In total, 25 healthy controls (mean age, 25 years ± 4 [SD]; 13 women) and 25 participants with chronic wrist pain (mean age, 39 years ± 16; 14 men) were included. Overall image quality (P = .002) and less presence of artifacts at PD-weighted fat-suppressed MRI were superior at 7 T. T1- and T2-weighted MRI were superior at 3 T (both P < .001), as was fat suppression (P < .001). Visualization of cartilage was superior at 7 T (P < .001), while visualization of the TFCC (P < .001) and scapholunate (P = .048) and lunotriquetral (P = .04) ligaments was superior at 3 T. Interreader reliability showed slight to substantial agreement for the detected pathologic conditions (κ = 0.20-0.64). Conclusion A 7-T MRI of the wrist had potential advantages over 3-T MRI, particularly in cartilage assessment. However, superiority was not shown for all parameters; for example, visualization of the triangular fibrocartilage complex and wrist ligaments was superior at 3 T. © RSNA, 2023 Supplemental material is available for this article.

Does indocyanine green fluorescence angiography impact the intraoperative choice of procedure in free vascularized medial femoral condyle grafting for scaphoid nonunions?

Background

Free vascularized medial femoral condyle (MFC) bone grafts can lead to increased vascularity of the proximal pole and restore scaphoid architecture in scaphoid nonunions. The intraoperative perfusion assessment of the bone graft is challenging because the conventional clinical examination is difficult. Indocyanine green (ICG) angiography has previously been shown to provide a real-time intraoperative evaluation of soft tissue perfusion in reconstructive surgery. The present study investigated the utility of ICG angiography in patients treated with a free medial femoral condyle graft for scaphoid nonunions.

Methods

We performed a retrospective analysis of patients with scaphoid nonunions, in which ICG angiography was used intraoperatively for perfusion assessment. The medical records, radiographs, intraoperative imaging, and operative reports of all patients were reviewed. Intraoperative ICG dye was administered intravenously, and laser angiography was performed to assess bone perfusion. The scaphoid union was examined using postoperative CT scans.

Results

Two patients had documented osteonecrosis of the proximal pole at the time of surgery. Four patients received a nonvascularized prior bone graft procedure, and a prior spongiosa graft procedure was performed in one patient. The mean time from injury to the MFC bone graft surgery was 52.7 months, and the mean time from prior failed surgery was 10.4 months. Perfusion of the vascular pedicle of the MFC and the periosteum could be detected in all patients. In two patients, even perfusion of the cancellous bone could be demonstrated by ICG angiography. Following transplantation of the bone graft, patency of the vascular anastomosis and perfusion of the periost were confirmed by ICG angiography in the assessed cases. No additional surgery regarding a salvage procedure for a scaphoid nonunion advanced collapse was necessary for the further course.

Conclusion

ICG-angiography has shown to be a promising tool in the treatment of scaphoid nonunion with medial femoral condyle bone grafts. It enables intraoperative decision making by assessment of the microvascular blood supply of the periosteum and the vascular pedicle of the MFC bone graft. Further studies need to evaluate the impact on union rates in a long-term follow-up.

Effects of Different Pressure Levels in Topical Negative Pressure Application—Analysis of Perfusion Parameters in a Clinical Skin Model Using Multimodal Imaging Techniques

The effects of topical negative pressure therapy (TNP) have been a subject of research for many years. In this study, we investigated new imaging devices to detect clinical changes that TNP causes on healthy tissue and identified differences in microcirculation created by different pressure levels. We used near-infrared spectroscopy (NIS), thermography, and a vein illuminator to measure the differences in oxygen saturation, tissue temperature, and vein pattern. A control group (−125 mmHg) and three comparison groups with only TNP dressing (Group 1), −25 mmHg (Group 2), and −175 mmHg (Group 3) were established. Thirty minutes of TNP on intact skin was followed by 30 min of resting. A total of 24 participants were measured by all imaging devices at predetermined time points. Oxygen saturation and skin temperature increased by 8.07% and 1.67 °C for the control group, 4.00% and 1.65 °C for Group 2, and 8.45% and 1.68 °C for Group 3. Group 1 showed a slight increase in oxygen saturation and a 2.7 °C increase in skin temperature. Over the 30 min following removal of TNP, oxygen saturation and temperature decreased gradually for all groups. The vein illuminator did not show significant differences in the venous pattern or flow. Our study showed that higher negative pressure values resulted in higher oxygen saturation and higher tissue temperature.

An In Vitro Approach for Investigating the Safety of Lipotransfer after Breast-Conserving Therapy

The application of lipotransfer after breast-conserving therapy (BCT) and irradiation in breast cancer patients is an already widespread procedure for reconstructing volume deficits of the diseased breast. Nevertheless, the safety of lipotransfer has still not been clarified yet due to contradictory data. The goal of this in vitro study was to further elucidate the potential effects of lipotransfer on the irradiated remaining breast tissue. The mammary epithelial cell line MCF-10A was co-cultured with the fibroblast cell line MRC-5 and irradiated with 2 and 5 Gy. Afterwards, cells were treated with conditioned medium (CM) from adipose-derived stem cells (ADSC), and the effects on the cellular functions of MCF-10A cells and on gene expression at the mRNA level in MCF-10A and MRC-5 cells were analyzed. Treatment with ADSC CM stimulated transmigration and invasion and decreased the surviving fraction of MCF-10A cells. Further, the expression of cytokines, extracellular, and mesenchymal markers was enhanced in mammary epithelial cells. Only an effect of ADSC CM on irradiated fibroblasts could be observed. The present data suggest epithelial–mesenchymal transition-like changes in the epithelial mammary breast cell line. Thus, the benefits of lipotransfer after BCT should be critically weighed against its possible risks for the affected patients.

Specific features of ex-obese patients significantly influence the functional cell properties of adipose-derived stromal cells

Adipose-derived stromal cells (ADSC) are increasingly used in clinical applications due to their regenerative capabilities. However, ADSC therapies show variable results. This study analysed the effects of specific factors of ex-obese patients on ADSC functions. ADSC were harvested from abdominal tissues (N = 20) after massive weight loss. Patients were grouped according to age, sex, current and maximum body mass index (BMI), BMI difference, weight loss method, smoking and infection at the surgical site. ADSC surface markers, viability, migration, transmigration, sprouting, differentiation potential, cytokine secretion, telomere length and mtDNA copy number were analysed. All ADSC expressed CD73, CD90, CD105, while functional properties differed significantly among patients. A high BMI difference due to massive weight loss was negatively correlated with ADSC proliferation, migration and transmigration, while age, sex or weight loss method had a smaller effect. ADSC from female and younger donors and individuals after weight loss by increase of exercise and diet change had a higher activity. Telomere length, mtDNA copy number, differentiation potential and the secretome did not correlate with patient factors or cell function. Therefore, we suggest that factors such as age, sex, increase of exercise and especially weight loss should be considered for patient selection and planning of regenerative therapies.

The Value of Negative-Pressure Wound Therapy and Flap Surgery in Hidradenitis Suppurativa – A Single Center Analysis of Different Treatment Options

Background

Hidradenitis suppurativa is manifested by painful abscesses and scarring of sweat glands. Axillary, inguinal and genital regions are mostly affected. Multiple options exist in the treatment of hidradenitis suppurativa. The aim of this retrospective, mono-center cohort study was to analyze the outcome of different treatment methods after radical excision of hidradenitis suppurativa.

Methods

We retrospectively evaluated the treatment strategy and recurrence rate of hidradenitis suppurativa. We included all eligible patients of legal age between February 2003 and October 2021, with the diagnosis of Hidradenitis suppurativa and the necessity for surgical treatment. All patients with surgical treatment and direct wound closure by suture were excluded. Bacterial load and flora were analyzed for primary and secondary reconstruction in combination with negative-pressure wound therapy. Patient data were analyzed for recurrence rate and remission time according to different reconstructive techniques.

Results

In 44 affected anatomical sites (n = 23 patients) we treated 15 patients with negative-pressure wound therapy. Bacterial load and flora were lower in the last wound swab of patients with multi-surgical procedures (22 localizations) compared to the first wound swab independent of the use of negative-pressure wound therapy.

Wound closure, independent of a direct and multi-stage procedure was achieved by local fasciocutaneous flaps (n = 12), secondary intention healing (n = 7), secondary intention healing with buried chip skin grafts (n = 10), or split-thickness skin grafts (n = 15). Radical excision combined with split-thickness skin grafts showed the lowest recurrence rate in the follow-up (16%; n = 4).

Conclusion

Radical excision of hidradenitis suppurativa as gold standard for surgical treatment combined with negative-pressure wound therapy as multi-stage procedures ultimately reduced bacterial load and flora in our study. The use of split-thickness skin grafts showed the lowest recurrence rate.

Microvascular development in the rat arteriovenous loop model in vivo-A step by step intravital microscopy analysis

The arteriovenous (AV) loop model is a key technique to solve one of the major problems of tissue engineering-providing adequate vascular support for a tissue construct of significant size. However, the molecular and cellular mechanisms of vascularization and factors influencing the generation of new tissue in the AV loop are still poorly understood. We previously established a novel intravital microscopy approach to study these events. In this study, we implanted our observation chamber filled with two types of hydrogels such as fibrin and methacrylate gelatin (GelMA) and performed intravital microscopy (IVM) on days 7, 14, and 21. Initial microvessel formation was observed in GelMA on day 14, while the vessel network showed clear indicators of network rearrangement and maturation on day 21. No visible microvessels were observed in fibrin. The chambers were explanted on day 21. Histological examination revealed higher numbers of microvessels in GelMA compared to fibrin, while the AV loop was thrombosed in all fibrin constructs, possibly due to matrix degradation. GelMA proved to be an ideal matrix for IVM studies in the AV loop model due to its slow degradation and transparency. This IVM model can be employed as a novel tool for live and thus faster comprehension of crucial events in the tissue regeneration process, which can improve tissue engineering application.

Improving the Safety of DIEP Flap Transplantation: Detailed Perforator Anatomy Study Using Preoperative CTA

Background: Deep inferior epigastric perforator and muscle sparing transverse rectus abdominis muscle flaps are commonly used flaps for autologous breast reconstruction. CT-angiography allows to analyse the perforator course preoperatively. Our aim was to compare the different aspects of perforator anatomy in the most detailed study. Methods: CT-angiographies of 300 female patients with autologous breast reconstruction of 10 years were analysed regarding the anatomy of the deep inferior epigastric artery and every perforator. Results: Overall, 2260 perforators were included. We identified correlations regarding the DIEA branching point and number of perforators and their intramuscular course. The largest perforator emerged more often from the medial branch of the DIEA than the smaller perforators (70% (416/595) vs. 54% (878/1634), p < 0.001) and more often had a direct connection to the SIEV (large 67% (401/595) vs. small 39% (634/1634), p < 0.01). Medial row perforators were larger than the laterals (lateral 1.44 mm ± 0.43 (n = 941) vs. medial 1.58 mm ± 0.52 (n = 1304) (p < 0.001)). The larger and more medial the perforator, the more likely it was connected to the SIEV: perforators with direct connection to the SIEV had a diameter of 1.65 mm ± 0.53 (n = 1050), perforators with indirect connection had a diameter of 1.43 ± 0.43 (n = 1028), perforators without connection had a diameter of 1.31 mm ± 0.37 (n = 169) (p < 0.001). Medial perforators were more often directly connected to the SIEV than lateral perforators (medial 56% (723/1302) vs. lateral 35% (327/941), p < 0.001). A lateral perforator more often had a short intramuscular course than medial perforators (69% (554/800) vs. 45% (474/1055), p < 0.001), which was also more often observed in the case of a small perforator and a caudal exit of the rectus sheath. Conclusion: The largest perforator emerges more often from the medial branch of the DIEA and frequently has a direct connection to the SIEV, making medial row perforators ideal for DIEP flap transplantation.

Intraoperative Blood Flow Analysis of DIEP vs. ms-TRAM Flap Breast Reconstruction Combining Transit-Time Flowmetry and Microvascular Indocyanine Green Angiography

Background: Vascular patency is the key element for high flap survival rates. The purpose of this study was to assess and compare the blood flow characteristics of deep inferior epigastric perforator (DIEP) and muscle-sparing transverse rectus abdominis musculocutaneous (ms-TRAM) flaps for autologous breast reconstruction. Methods: This prospective clinical study combined Transit-Time Flowmetry and microvascular Indocyanine Green Angiography for the measurement of blood flow volume, vascular resistance, and intrinsic transit time. Results: Twenty female patients (mean age, 52 years) received 24 free flaps (14 DIEP and 10 ms-TRAM flaps). The mean arterial blood flow of the flap in situ was 7.2 ± 1.9 mL/min in DIEP flaps and 11.5 ± 4.8 mL/min in ms-TRAM flaps (p < 0.05). After anastomosis, the mean arterial blood flow was 9.7 ± 5.6 mL/min in DIEP flaps and 13.5 ± 4.2 mL/min in ms-TRAM flaps (p = 0.07). The arterial vascular resistance of DIEP flaps was significantly higher than that of ms-TRAM flaps. The intrinsic transit time of DIEP flaps was 52 ± 18 s, and that of ms-TRAM flaps was 33 ± 11 s (p < 0.05). The flap survival rate was 100%. One DIEP flap with the highest intrinsic transit time (77 s) required surgical revision due to arterial thrombosis. Conclusion: In this study, we established the blood flow characteristics of free DIEP and ms-TRAM flaps showing different blood flow rates, vascular resistances, and intrinsic transit times. These standard values will help to determine the predictive values for vascular compromise, hence improving the safety of autologous breast reconstruction procedures.

Microsurgical Transplantation of Pedicled Muscles in an Isolation Chamber—A Novel Approach to Engineering Muscle Constructs via Perfusion-Decellularization

Decellularized whole muscle constructs represent an ideal scaffold for muscle tissue engineering means as they retain the network and proteins of the extracellular matrix of skeletal muscle tissue. The presence of a vascular pedicle enables a more efficient perfusion-based decellularization protocol and allows for subsequent recellularization and transplantation of the muscle construct in vivo. The goal of this study was to create a baseline for transplantation of decellularized whole muscle constructs by establishing an animal model for investigating a complete native muscle isolated on its pedicle in terms of vascularization and functionality. The left medial gastrocnemius muscles of 5 male Lewis rats were prepared and raised from their beds for in situ muscle stimulation. The stimulation protocol included twitches, tetanic stimulation, fatigue testing, and stretching of the muscles. Peak force, maximum rate of contraction and relaxation, time to maximum contraction and relaxation, and maximum contraction and relaxation rate were determined. Afterwards, muscles were explanted and transplanted heterotopically in syngeneic rats in an isolation chamber by microvascular anastomosis. After 2 weeks, transplanted gastrocnemius muscles were exposed and stimulated again followed by intravascular perfusion with a contrast agent for µCT analysis. Muscle constructs were then paraffin embedded for immunohistological staining. Peak twitch and tetanic force values all decreased significantly after muscle transplantation while fatigue index and passive stretch properties did not differ between the two groups. Vascular analysis revealed retained perfused vessels most of which were in a smaller radius range of up to 20 µm and 45 µm. In this study, a novel rat model of heterotopic microvascular muscle transplantation in an isolation chamber was established. With the assessment of in situ muscle contraction properties as well as vessel distribution after 2 weeks of transplantation, this model serves as a base for future studies including the transplantation of perfusion-decellularized muscle constructs.

Impact of Endothelial Progenitor Cells in the Vascularization of Osteogenic Scaffolds

The microvascular endothelial network plays an important role in osteogenesis, bone regeneration and bone tissue engineering. Endothelial progenitor cells (EPCs) display a high angiogenic and vasculogenic potential. The endothelialization of scaffolds with endothelial progenitor cells supports vascularization and tissue formation. In addition, EPCs enhance the osteogenic differentiation and bone formation of mesenchymal stem cells (MSCs). This study aimed to investigate the impact of EPCs on vascularization and bone formation of a hydroxyapatite (HA) and beta-tricalcium phosphate (ß-TCP)–fibrin scaffold. Three groups were designed: a scaffold-only group (A), a scaffold and EPC group (B), and a scaffold and EPC/MSC group (C). The HA/ß–TCP–fibrin scaffolds were placed in a porous titanium chamber permitting extrinsic vascularization from the surrounding tissue. Additionally, intrinsic vascularization was achieved by means of an arteriovenous loop (AV loop). After 12 weeks, the specimens were explanted and investigated by histology and CT. We were able to prove a strong scaffold vascularization in all groups. No differences regarding the vessel number and density were detected between the groups. Moreover, we were able to prove bone formation in the coimplantation group. Taken together, the AV loop is a powerful tool for vascularization which is independent from scaffold cellularization with endothelial progenitor cells’ prior implantation.

A Personalized Approach to Treat Advanced Stage Severely Contracted Joints in Dupuytren’s Disease with a Unique Skeletal Distraction Device—Utilizing Modern Imaging Tools to Enhance Safety for the Patient

Background: While surgical therapy for Dupuytren’s disease is a well-established standard procedure, severe joint flexion deformities in advanced Dupuytren’s disease remain challenging to treat. Skeletal distraction has proven to be an additional treatment option. Methods: We analyzed the surgical treatment algorithm, including the application of a skeletal distraction device, in patients with a flexion deformity due to Dupuytren’s disease, Iselin stage III or IV, who were operated on from 2003 to 2020 in our department. Results: From a total of 724 patients, we included the outcome of 55 patients’ fingers in this study, who had undergone additional skeletal joint distraction with our Erlangen device. Additional fasciotomy or fasciectomy, in a one- or two-staged procedure, was performed in all patients, according to the individual findings and necessities. The range of motion of the PIP joint improved from 12° to 53°. A number of complications, in all steps of the treatment, were noted in a total of 36.4% of patients, including the development of fractures (16.4%), followed by vessel injury, pin infections, and complex regional pain syndrome (5%). Conclusions: Additional skeletal distraction improves the range of motion of severely contracted joints in Dupuytren’s disease. Nevertheless, careful patient selection is necessary, due to the moderate rate of complications.

Anatomical Study of all Carpal and Adjoining Bones of the Wrist using 3D CT Reconstruction - Finding the ultimate Biomechanical Theory

BACKGROUND

The complex interplay of single wrist bones acting in combination with their ligamentous connections is still not fully understood. In this regard various theories exist, divisible in columnar and ring/row theories. The object of this study was to examine the mobility of the individual carpal bones as well as the ulna and metacarpals relative to each other in wrists of cadaveric hands using CT scans.

METHODS

The regular wrist mobility of a total of 21 cadaveric hands was examined by CT imaging in neutral position, radial/ulnar abduction as well as wrist flexion and extension. The data were evaluated as 3D models by using a standardized global coordinate system and object coordinate systems. Rotation and translation of each carpal bone as well as radius/ulna and all metacarpal bones were evaluated.

RESULTS

The principal motion took place in the carpus between the radius and the proximal carpal row followed by the midcarpal joint and the carpometacarpal joints and not mainly between the individual bones of a row. The scaphoid moves out of its row aggregate mainly during flexion and adapts to the motion of the distal carpal row. The trapezium and first metacarpal bones play a specific role detached from the remaining bones.

CONCLUSIONS

With this study, a better understanding of the motion of the individual bones of the carpus, the metacarpals and the radius/ulna is shown. The study supports the row theory, where most motion takes place between the individual rows and not between the carpal bones, leaving the scaphoid and the first ray in a special role between the rows.

Intra- and Early Postoperative Evaluation of Malperfused Areas in an Irradiated Random Pattern Skin Flap Model Using Indocyanine Green Angiography and Near-Infrared Reflectance-Based Imaging and Infrared Thermography

Background: Assessment of tissue perfusion after irradiation of random pattern flaps still remains a challenge. Methods: Twenty-five rats received harvesting of bilateral random pattern fasciocutaneous flaps. Group 1 served as nonirradiated control group. The right flaps of the groups 2–5 were irradiated with 20 Gy postoperatively (group 2), 3 × 12 Gy postoperatively (group 3), 20 Gy preoperatively (group 4) and 3 × 12 Gy preoperatively (group 5). Imaging with infrared thermography, indocyanine green angiography and near-infrared reflectance-based imaging were performed to detect necrotic areas of the flaps. Results: Analysis of the percentage of the necrotic area of the irradiated flaps showed a statistically significant increase from day 1 to 14 only in group 5 (p < 0.05). Indocyanine green angiography showed no differences (p > 0.05) of the percentage of the nonperfused area between all days in group 1 and 3, but a decrease in group 2 in both the left and the right flaps. Infrared thermography and near-infrared reflectance-based imaging did not show evaluable differences. Conclusion: Indocyanine green angiography is more precise in prediction of necrotic areas in random pattern skin flaps when compared to hyperspectral imaging, thermography or clinical impression. Preoperative fractional irradiation with a lower individual dose but a higher total dose has a more negative impact on flap perfusion compared to higher single stage irradiation.

Vessel grafts for tissue engineering revisited-Vessel segments show location-specific vascularization patterns in ex vivo ring assay

OBJECTIVE

Transplantation of prefabricated tissue-engineered flaps can be a potential alternative for healing large tissue defects. Providing adequate vascular supply for an engineered tissue construct is one of the key points in establishing successful tissue engineering-based treatment approaches. In tissue engineering-based vascularization techniques like the arteriovenous loop, vascular grafts with high angiogenic potential can help to enhance neovascularization and tissue formation. Therefore, our study aimed to compare the angiogenic potential of vascular grafts from different locations in the rat.

METHODS

The angiogenic activity was investigated by an ex vivo vessel outgrowth ring assay using 1-mm height vascular segments embedded in fibrin for 2 weeks.

RESULTS

Maximum vessel outgrowth was observed on Days 10-12. Upper extremity vessels exhibited stronger outgrowth than lower extremity vessels. Moreover, arterial vessels demonstrated higher angiogenic potential compared with venous vessels.

CONCLUSION

Collectively, our ex vivo findings suggest that upper extremity arterial vessels have a higher angiogenic capacity, which could be used to improve neovascularization and tissue formation in tissue engineering.

Bilateral free flap breast reconstruction using venous cross-over bypass to contralateral internal mammary artery for salvaging thrombosed arterial anastomosis in unilateral repeated irradiation of the breast: A case report

Adjuvant radiotherapy in breast cancer patients might enhance complications after autologous breast reconstruction, including thrombosis of the internal mammary artery (IMA) precluding its use as recipient vessel. This case report shows a salvage procedure for thrombosis of the IMA during bilateral autologous breast reconstruction in a 51-year-old patient who had undergone repeated irradiation of the chest wall after Hodgkin's disease and recurrent breast carcinoma of the right side. After mastectomy of the right breast and prophylactic mastectomy of the left breast, the patient desired breast reconstruction with autologous tissue. During simultaneous bilateral breast reconstruction using two deep inferior epigastric perforator (DIEP) flaps anastomosed to the left and right inframammary vessels, arterial anastomosis to the right IMA was not feasible due to arterial thrombosis. A salvage procedure using an interpositional cephalic vein graft as a crossover bypass and a subcutaneous presternal tunnel was used. The inferior epigastric artery of the right DIEP flap was anastomosed to the venous bypass, which was anastomosed to the contralateral IMA. Both flaps healed without any complications during the postoperative course and follow up of 6 months. The presented case shows the feasibility of a cross-over venous bypass procedure during bilateral breast reconstruction as salvage maneuver for the arterial anastomosis after repeated radiation of the unilateral breast.

The third dimension in perforator mapping-Comparison of Cinematic Rendering and maximum intensity projection in abdominal-based autologous breast reconstruction

BACKGROUND

Cinematic Rendering (CR) is a recently introduced post-processing three-dimensional (3D) visualization imaging tool. The aim of this study was to assess its clinical value in the preoperative planning of deep inferior epigastric artery perforator (DIEP) or muscle-sparing transverse rectus abdominis myocutaneous (MS-TRAM) flaps, and to compare it with maximum intensity projection (MIP) images. The study presents the first application of CR for perforator mapping prior to autologous breast reconstruction.

METHODS

Two senior surgeons independently analyzed CR and MIP images based on computed tomography angiography (CTA) datasets of 20 patients in terms of vascular pedicle characteristics, the possibility to harvest a DIEP or MS-TRAM flap, and the side of the flap harvest. We calculated inter- and intra-observer agreement in order to examine the accordance of both image techniques.

RESULTS

We observed a good inter- and intra-observer agreement concerning the type of flap and the side of the flap harvest. However, the agreement on the pedicle characteristics varies depending on the considered variable. Both investigators identified a significantly higher number of perforators with MIP compared with CR (observer 1, p<0.0001 and observer 2, p<0.0385).

CONCLUSION

The current study serves as an explorative study, showing first experiences with CR in abdominal-based autologous breast reconstruction. In addition to MIP images, CR might improve the surgeon's understanding of the individual's anatomy. Future studies are required to compare CR with other 3D visualization tools and its possible effects on operative parameters.

[Temporarily Transfixation of the distal interphalangeal Joint in Mallet fingers]

PURPOSE

This retrospective, unicenter cohort study analyse the clinical and subjective results following temporarily K-wire transfixation of the distal interphalangeal joint (DIPJ) in hyperextension in Mallet fingers.

PATIENTS AND METHODS

By means of a self-designed questionnaire demographic data, patient´s satisfaction (0 = unsatisfied, 10 = very satisfied), persisting pain (yes/no), postoperative complications, and the Quick-DASH score were evaluated. In addition, range of motion of the DIPJ was measured with use of a self-designed template for self-evaluation by the patients. Questionnaire and template were send to 132 patients in whom a Mallet finger was treated between January 2009 and December 2019 with K-wire transfixation of the DIPJ. 65 (49,2 %) questionnaires and templates from 40 men and 25 women with an average age of 53.3 years returned. There were 40 acute and 25 chronic Mallet fingers in 35 (54 %) middle, 19 (29 %) small, 10 (15 %) ring, and 1 (2 %) index fingers. The extension deficit was classified according to Crawford.

RESULTS

According to the Crawford classification, there were 75 % excellent, 14 % good, and 11 % satisfied results. With an average of 7,9 points the patients were very satisfied. 15 patients reported about complications with six complaining persisting pain. The Quick-DASH score averaged 5.4 points.

CONCLUSION

The treatment of Mallet fingers by transfixation of the DIPJ using a K-wire is an appropriate method leading to a good.

Gelatin methacryloyl is a slow degrading material allowing vascularization and long-term usein vivo

In situtissue engineering is an emerging field aiming at the generation of ready-to-use three-dimensional tissues. One solution to supply a proper vascularization of larger tissues to provide oxygen and nutrients is the arteriovenous loop (AVL) model. However, for this model, suitable scaffold materials are needed that are biocompatible/non-immunogenic, slowly degradable, and allow vascularization. Here, we investigate the suitability of the known gelatin methacryloyl (GelMA)-based hydrogel forin-situtissue engineering utilizing the AVL model. Rat AVLs are embedded by two layers of GelMA hydrogel in an inert PTFE chamber and implanted in the groin. Constructs were explanted after 2 or 4 weeks and analyzed. For this purpose, gross morphological, histological, and multiphoton microscopic analysis were performed. Immune response was analyzed based on anti-CD68 and anti-CD163 staining of immune cells. The occurrence of matrix degradation was assayed by anti-MMP3 staining. Vascularization was analyzed by anti-α-smooth muscle actin staining, multiphoton microscopy, as well as expression analysis of 53 angiogenesis-related proteins utilizing a proteome profiler angiogenesis array kit. Here we show that GelMA hydrogels are stable for at least 4 weeks in the rat AVL model. Furthermore, our data indicate that GelMA hydrogels are biocompatible. Finally, we provide evidence that GelMA hydrogels in the AVL model allow connective tissue formation, as well as vascularization, introducing multiphoton microscopy as a new methodology to visualize neovessel formation originating from the AVL. GelMA is a suitable material forin situandin vivoTE in the AVL model.

Polytetrafluoroethylene (PTFE) suture vs fiberwire and polypropylene in flexor tendon repair

BACKGROUND

In this study, we evaluate the value of novel suture material based on monofilamentous-extruded polyfluoroethylene (PTFE) compared to polypropylene (PPL) and Fiberwire (FW).

MATERIALS AND METHODS

60 flexor tendons were harvested from fresh cadaveric upper extremities. 4-0 sutures strands were used in the PPL, FW and PTFE group. Knotting properties and mechanical characteristics of the suture materials were evaluated. A 4-strand locked cruciate (Adelaide) or a 6-strand (M-Tang) suture technique was applied as core sutures for a tendon repair. Two-way ANOVA tests were performed with the Bonferroni correction.

RESULTS

Stable knotting was achieved with 5 throws with the PPL material, 7 throws for FW and 9 throws for PTFE. In the PPL group, linear tensile strength was 45.92 ± 12.53 N, in the FW group 80.11 ± 18.34 N and in the PTFE group 76.16 ± 29.10 N. FW and PTFE are significantly stronger than PPL but show no significant difference among each other. Similar results were obtained in the subgroup comparisons for different repair techniques. The Adelaide and the M-Tang knotting technique showed no significant difference.

CONCLUSION

Fiberwire showed superior handling and knotting properties in comparison to PTFE. However, PTFE allows easier approximation of the stumps. In both, M-Tang and Adelaide repairs, PTFE was equal to FW in terms of repair strength. Both PTFE and FW provide for a robust tendon repair so that early active motion regimens for rehabilitation can be applied.

Free Transplantation of a Tissue Engineered Bone Graft into an Irradiated, Critical-Size Femoral Defect in Rats

Healing of large bone defects remains a challenge in reconstructive surgery, especially with impaired healing potential due to severe trauma, infection or irradiation. In vivo studies are often performed in healthy animals, which might not accurately reflect the situation in clinical cases. In the present study, we successfully combined a critical-sized femoral defect model with an ionizing radiation protocol in rats. To support bone healing, tissue-engineered constructs were transferred into the defect after ectopic preossification and prevascularization. The combination of SiHA, MSCs and BMP-2 resulted in the significant ectopic formation of bone tissue, which can easily be transferred by means of our custom-made titanium chamber. Implanted osteogenic MSCs survived in vivo for a total of 18 weeks. The use of SiHA alone did not lead to bone formation after ectopic implantation. Analysis of gene expression showed early osteoblast differentiation and a hypoxic and inflammatory environment in implanted constructs. Irradiation led to impaired bone healing, decreased vascularization and lower short-term survival of implanted cells. We conclude that our model is highly valuable for the investigation of bone healing and tissue engineering in pre-damaged tissue and that healing of bone defects can be substantially supported by combining SiHA, MSCs and BMP-2.

Enhanced vascularization andde novotissue formation in hydrogels made of engineered RGD-tagged spider silk proteins in the arteriovenous loop model

Due to its low immunogenic potential and the possibility to fine-tune their properties, materials made of recombinant engineered spider silks are promising candidates for tissue engineering applications. However, vascularization of silk-based scaffolds is one critical step for the generation of bioartificial tissues and consequently for clinical application. To circumvent insufficient vascularization, the surgically induced angiogenesis by means of arteriovenous loops (AVL) represents a highly effective methodology. Here, previously established hydrogels consisting of nano-fibrillary recombinant eADF4(C16) were transferred into Teflon isolation chambers and vascularized in the rat AVL model over 4 weeks. To improve vascularization, also RGD-tagged eADF4(C16) hydrogels were implanted in the AVL model over 2 and 4 weeks. Thereafter, the specimen were explanted and analyzed using histology and microcomputed tomography. We were able to confirm biocompatibility and tissue formation over time. Functionalizing eADF4(C16) with RGD-motifs improved hydrogel stability and enhanced vascularization even outperforming other hydrogels, such as fibrin. This study demonstrates that the scaffold ultrastructure as well as biofunctionalization with RGD-motifs are powerful tools to optimize silk-based biomaterials for tissue engineering applications.

Abdominal Panniculectomy Can Simplify Kidney Transplantation in Obese Patients

BACKGROUND

Obesity is frequently present in patients suffering from end-stage renal disease (ESRD). However, overweight kidney transplant candidates are a challenge for the transplant surgeon. Obese patients tend to develop a large abdominal panniculus after weight loss creating an area predisposed to wound-healing disorders. Due to concerns about graft survival and postoperative complications after kidney transplantation, obese patients are often refused in this selective patient cohort. The study aimed to analyze the effect of panniculectomies on postoperative complications and transplant candidacy in an interdisciplinary setting.

METHODS

A retrospective database review of 10 cases of abdominal panniculectomies performed in patients with ESRD prior to kidney transplantation was conducted.

RESULTS

The median body mass index was 35.2 kg/m2 (range 28.5-53.0 kg/m2) at first transplant-assessment versus 31.0 kg/m2 (range 28.0-34.4 kg/m2) at panniculectomy, and 31.6 kg/m2 (range 30.3-32.4 kg/m2) at kidney transplantation. We observed no major postoperative complications following panniculectomy and minor wound-healing complications in 2 patients. All aside from 1 patient became active transplant candidates 6 weeks after panniculectomy. No posttransplant wound complications occurred in the transplanted patients.

CONCLUSION

Abdominal panniculectomy is feasible in patients suffering ESRD with no major postoperative complications, thus converting previously ineligible patients into kidney transplant candidates. An interdisciplinary approach is advisable in this selective patient cohort.

Novel imaging methods reveal positive impact of topical negative pressure application on tissue perfusion in an in vivo skin model

The influence of topical negative pressure application (TNPA) on tissue perfusion still remains controversial. TNPA was applied for 30 minutes on intact skin of 21 healthy participants. Measurements of tissue oxygen saturation and tissue temperature as signs of tissue perfusion were performed before application of the TNPA, directly after removal of the TNPA and 5, 10, 15, 20, and 30 minutes after removal of the dressing using the near infrared imaging (NIRI) and a thermal imaging camera. Tissue oxygen saturation showed an increase from 67.7% before applying the TNPA to 76.1% directly after removal of TNPA, followed by a decrease of oxygen saturation 30 minutes after removal of TNPA. The measured temperature of the treated skin area increased from 32.1°C to 36.1°C after removal of TNPA with a consecutive decrease of the temperature 30 minutes after removal. TNPA resulted in both a higher tissue oxygen saturation and a higher skin temperature after 30 minutes compared to the beginning. TNPA increases both tissue oxygen saturation and skin temperature as sign of an increase of tissue perfusion. NIRI and thermal imaging proved to be useful for measuring changes in tissue perfusion.

Watching the Vessels Grow: Establishment of Intravital Microscopy in the Arteriovenous Loop Rat Model

Tissue engineering in reconstructive surgery seeks to generate bioartificial tissue substitutes. The arteriovenous (AV) loop allows the generation of axially vascularized tissue constructs. Cellular mechanisms of this vascularization process are largely unclear. In this study, we developed two different chamber models for intravital microscopy and imaging of the AV loop in the rat. Multiple design variations were implanted and the stability of the chamber and AV loop patency was tested in vivo. Our novel chamber facilitates repetitive observation of the AV loop using fluorescence-enhanced intravital microscopy. This technique can be used for daily evaluation of leukocyte-endothelial cell interactions, vascularization, and tissue formation in the AV loop model on 14 consecutive days. Therefore, our newly developed model for intravital microscopy will provide better understanding of cellular and molecular processes in tissue engineering in the AV loop. Moreover, it supports initiation of the novel approaches for therapeutic applications. Impact statement In the Arteriovenous (AV) loop, axially vascularized tissue can be generated and modified using different tissue engineering approaches. Cellular mechanisms of this vascularization process are largely unclear. We managed to develop an intravital microscopy model for long-term observation of intravascular and perivascular events in the AV loop. Leukocyte-endothelial cell interactions, vascularization, and tissue formation in the AV loop can now be evaluated on a day-to-day basis. This will provide better understanding of cellular and molecular processes happening during tissue engineering within the AV loop.

[Reconstruction of oncological defects of the perianal region]

In addition to the progressive development of surgical oncological techniques for malignant tumors of the rectum, anal canal and vulva, reconstructive procedures after oncological interventions in the perianal region represent a cornerstone in the postoperative quality of life of patients. Modern treatment modalities for rectal cancer with neoadjuvant chemoradiotherapy increase the survival rate and simultaneously reduce the risk of local recurrence to 5-10%, especially by cylindrical extralevatory extirpation of the rectum. The price for increased surgical radicality and improved oncological safety is the acceptance of larger tissue defects. Simple suture closure of perineal wounds often does not primarily heal, resulting in wound dehiscence, surgical site infections and formation of chronic fistulas and sinuses. The interdisciplinary one-stage or two-stage reconstruction of the perianal region with well-vascularized tissue has proven to be a reliable procedure to prevent or control such complications.

External Screw-Threaded Traction Device Helps Optimize Finger Joint Mobility in Severe Stage III and IV Dupuytren Disease

Background

Treating advanced finger joint contractures from Dupuytren disease remains a challenge. We evaluated the effectiveness of a skeletal distraction device versus alternative treatment options.

Material/Methods

We analyzed the surgical treatment of contracted finger joints in stage III and stage IV Dupuytren’s disease over a 10-year period. Data were obtained from inpatient and outpatient medical records, including postoperative clinical examinations and extended Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire scores. Complications of infection, postoperative pain, and wound healing disorders were recorded.

Results

A total of 79 patients (83 hands) were assigned to 2 treatment groups. Patients in group 1 underwent an initial open transection of the main fibrous cord, Z-plasty, distraction with the Erlangen external distraction device, and fasciectomy. The distraction period was 13 to 81 days (mean 31 days). Group 2 underwent a conventional single-stage fasciectomy and arthrolysis. DASH scores and subjective patient satisfaction were lower in group 1 (20.7/33%) than in group 2 (10.3/50%). However, the staged approach of group 1 to treat proximal interphalangeal joint contractures in the long term (improvement >40%) was more effective than the approach of group 2 (>33%). Distraction device pin infections occurred in 20% of hands. Postoperative pain and complex regional pain syndrome type I occurred in 25% of hands in group 1 and 3% in group 2.

Conclusions

A screw thread driven external fixation device is useful in end-stage Dupuytren’s finger joint contractures. It is indicated when joint contractures are advanced and simple arthrolysis is insufficient.

Less is more - retrospective comparison of shoulder strength and range of motion between conventional and muscle-sparing harvesting technique of a latissimus dorsi flap

BACKGROUND

The muscle-sparing latissimus dorsi flap poses an alternative to the conventional latissimus dorsi flap when a defect requires a smaller flap volume with a long vascular pedicle. The aim of the study was to analyze the functional outcome following muscle-sparing versus conventional harvest of a latissimus dorsi flap.

MATERIAL AND METHODS

Patients who received a muscle-sparing latissimus dorsi muscle flap transplantation (group 1) and patients with a complete latissimus dorsi muscle flap harvest (group 2) for defect reconstruction at the University Hospital of Erlangen between 2007 and 2016 were examined. The evaluation included a physical examination with the measurement of strength and range of motion of the shoulder of both the donor side as well as the nonoperated side. Furthermore, the DASH score was evaluated. Additionally, patients in group 1 received a neurophysiological examination.

RESULTS

The DASH score did not show statistically significant differences between both groups. Both strength (p = 0.031) and range of motion (p<0.05) of the shoulder of the donor side were statistically significantly lower than the nonoperated side in group 2, while no difference was found in group 1. The neurophysiological examination in group 1 showed a reduced nerve conduction velocity of the donor side as compared to the nonoperated side in most patients (60% and n = 3).

CONCLUSION

Harvesting the muscle-sparing latissimus dorsi flap leads to less functional impairments of the shoulder than harvesting the complete latissimus dorsi flap.

Actually Seeing What Is Going on - Intravital Microscopy in Tissue Engineering

Intravital microscopy (IVM) study approach offers several advantages over in vitro, ex vivo, and 3D models. IVM provides real-time imaging of cellular events, which provides us a comprehensive picture of dynamic processes. Rapid improvement in microscopy techniques has permitted deep tissue imaging at a higher resolution. Advances in fluorescence tagging methods enable tracking of specific cell types. Moreover, IVM can serve as an important tool to study different stages of tissue regeneration processes. Furthermore, the compatibility of different tissue engineered constructs can be analyzed. IVM is also a promising approach to investigate host reactions on implanted biomaterials. IVM can provide instant feedback for improvising tissue engineering strategies. In this review, we aim to provide an overview of the requirements and applications of different IVM approaches. First, we will discuss the history of IVM development, and then we will provide an overview of available optical modalities including the pros and cons. Later, we will summarize different fluorescence labeling methods. In the final section, we will discuss well-established chronic and acute IVM models for different organs.

Bone Structure Analysis of the Radius Using Ultrahigh Field (7T) MRI: Relevance of Technical Parameters and Comparison with 3T MRI and Radiography

Bone fractal signature analysis (FSA-also termed bone texture analysis) is a tool that assesses structural changes that may relate to clinical outcomes and functions. Our aim was to compare bone texture analysis of the distal radius in patients and volunteers using radiography and 3T and 7T magnetic resonance imaging (MRI)-a patient group (n = 25) and a volunteer group (n = 25) were included. Participants in the patient group had a history of chronic wrist pain with suspected or confirmed osteoarthritis and/or ligament instability. All participants had 3T and 7T MRI including T1-weighted turbo spin echo (TSE) sequences. The 7T MRI examination included an additional high-resolution (HR) T1 TSE sequence. Radiographs of the wrist were acquired for the patient group. When comparing patients and volunteers (unadjusted for gender and age), we found a statistically significant difference of horizontal and vertical fractal dimensions (FDs) using 7T T1 TSE-HR images in low-resolution mode (horizontal: p = 0.04, vertical: p = 0.01). When comparing radiography to the different MRI sequences, we found a statistically significant difference for low- and high-resolution horizontal FDs between radiography and 3T T1 TSE and 7T T1 TSE-HR. Vertical FDs were significantly different only between radiographs and 3T T1 TSE in the high-resolution mode; FSA measures obtained from 3T and 7T MRI are highly dependent on the sequence and reconstruction resolution used, and thus are not easily comparable between MRI systems and applied sequences.