Free flaps: Outcomes and complications in head and neck reconstructions

Predicting reoperation and readmission for head and neck free flap patients using machine learning

BACKGROUND

To develop machine learning (ML) models predicting unplanned readmission and reoperation among patients undergoing free flap reconstruction for head and neck (HN) surgery.

METHODS

Data were extracted from the 2012-2019 NSQIP database. eXtreme Gradient Boosting (XGBoost) was used to develop ML models predicting 30-day readmission and reoperation based on demographic and perioperative factors. Models were validated using 2019 data and evaluated.

RESULTS

Four-hundred and sixty-six (10.7%) of 4333 included patients were readmitted within 30 days of initial surgery. The ML model demonstrated 82% accuracy, 63% sensitivity, 85% specificity, and AUC of 0.78. Nine-hundred and four (18.3%) of 4931 patients underwent reoperation within 30 days of index surgery. The ML model demonstrated 62% accuracy, 51% sensitivity, 64% specificity, and AUC of 0.58.

CONCLUSION

XGBoost was used to predict 30-day readmission and reoperation for HN free flap patients. Findings may be used to assist clinicians and patients in shared decision-making and improve data collection in future database iterations.

Outcomes of internal mammary artery perforator flap in head and neck reconstruction: A systematic review

This study aims to evaluate the functional and prognostic outcomes associated with the internal mammary artery perforator (IMAP) flap in various head and neck defect repairs, given the current lack of clarity on its effectiveness. We performed a systematic review of various databases: PubMed, Embase, Scopus, Web of Science, and ScienceDirect using keywords such as "Internal mammary artery perforator flap" and "IMAP." Screening and data extractions were performed by two individual reviewers. Articles were considered eligible if they included sufficient information on IMAP flap features, their applications in the head and neck, and outcomes. From 264 articles analyzed, 24 studies were included for qualitative analysis. Out of which, 125 patients who received internal mammary artery perforator flaps were included. Most of the patients, 103 (88%), received pedicled IMAP flaps, and 22 (12%) received IMAP free flaps. The second internal mammary artery (IMA) was favored as the single perforator (81.5%), with the combination of the first and second IMA being the primary choice for dual perforators (92.5%). IMAP flaps were predominantly single perforator flaps (65%), with 35% being dual perforator flaps. Among various applications, IMAP flaps are commonly employed in the reconstruction of neck defects (25.5%), pharyngocutaneous fistula repair (20.8%), and burn scar contracture restoration (8%). Only seven (5.6%) patients had flap complications, including venous congestion (1.6%), partial necrosis (1.6%), complete necrosis (1.6%), and incision dehiscence (0.8%). Donor sites were predominantly closed by the primary closure (92%). 3.2% of donor sites had minor complications. The average follow-up was 12.6 (IQR: 6-18) months. This systematic review highlights the effectiveness and safety of IMAP flaps in head and neck reconstruction, with positive outcomes and minimal complications.

Predictive factors of postoperative complications related to free flap reconstruction in head and neck cancer patients admitted to intensive care unit: a retrospective cohort study

BACKGROUND

The epidemiology and risk factors for postoperative complications related to free flap reconstruction in head and neck cancer patients admitted to the Intensive Care Unit (ICU) are unknown.

METHODS

We performed a retrospective cohort study of patients with free flap reconstruction of head and neck cancer between September 2015 and April 2023 admitted to the ICU of Beijing Tongren Hospital. The univariate and multivariate analyses were used to explore the risk factors for postoperative complications related to free flap reconstruction admitted to ICU, including flap necrosis, bleeding, fistula, and infection.

RESULTS

A total of 239 patients were included in this study, and 38 (15.9%) patients had postoperative complications related to free flap reconstruction. The median length of ICU stay was 1 day (interquartile range, 1-2 days). Multivariate analysis found that low BMI (P < 0.001), high postoperative CRP (P = 0.005), low hemoglobin (P = 0.012), and inadequate fluid intake (P < 0.05) were independent risk factors for complications.

CONCLUSIONS

Postoperative complications related to free flap reconstruction were common in this ICU population. Careful fluid management and monitoring of CRP and hemoglobin levels may reduce complications.

Molecular Genetic Analysis of Perioperative Colonization by Infection-Related Microorganisms in Patients Receiving Intraoral Microvascular Grafts

Background/Objectives: In oral and maxillofacial surgery, the reconstruction of defects often involves the transfer of skin tissue into the oral cavity utilizing microvascular grafts. This study investigates postoperative changes in microbial colonization following intraoral microvascular transplantation, as well as potential influencing factors. Methods: In 37 patients undergoing intraoral reconstructions, pre- and postoperative swabs were taken from the donor and recipient regions to quantify the seven selected marker bacteria using TaqMan PCRs. Patient-specific factors and clinical data were also recorded. Results: The infection-associated Acinetobacter baumannii tended to decrease postoperatively, while the infectious pathogens Pseudomonas aeruginosa, Enterococcus faecalis and the family of Enterobacteriaceae showed a postoperative increase without being directly associated with a clinical infection. Streptococcus mitis showed a significant postoperative decrease on buccal mucosa and increase on the graft surface (oral dysbiosis) and was significantly reduced or displaced by other bacteria (e.g., Mycoplasma salivarium, positive selection) when treated with ampicillin/sulbactam. Conclusions: The cutaneous microbiome of the graft adapts to the local intraoral environment. Postoperative shifts in oral bacterial colonization and an increase in infection-relevant bacteria were observed. These perioperative changes in colonization are also influenced by the administration of ampicillin/sulbactam. Consequently, single doses of antibiotics appear to be more beneficial compared to longer-term preventive use.

Prevalence and risk factors of postoperative delirium in tumor patients after free flap reconstruction: A systematic review and meta-analysis of case-control studies

BACKGROUND

Postoperative delirium is a severe complication of flap transplantation surgery, adversely affecting surgical prognoses. The intricate pathophysiology of postoperative delirium renders the elucidation of its risk factors challenging. This research aims to delineate the prevalence and the specific risk factors of postoperative delirium in patients with cancer undergoing free flap reconstruction through a systematic review and meta-analysis to enlighten proactive prevention measures.

METHODS

The researchers systematically queried both the international and Chinese databases. Searches were performed for publications from inception until September 14, 2023, using the terms "free tissue flaps," "delirium," "neoplasms," and "risk factors." Data synthesis and statistical analysis were conducted using Stata SE (version 15.0) to calculate the combined effect size for identified risk factors. Reported outcomes included weighted mean differences or odds ratios with their respective 95% confidence intervals.

RESULTS

Twelve case-control studies were included (ntotal = 3,256). Among them, 515 patients developed postoperative delirium after free flap surgery, compared with 2,741 patients who did not. The outcomes suggest that the risk factors include but are not limited to age, male, late neoplasm staging, use of hypnotic or antipsychotic, history of background diseases, psychiatric review, tracheotomy, and impaired wound healing. In contrast, early neoplasm staging and others are the protective factors with statistical significance. Multivariate analysis further identified significant correlations between preoperative albumin, perioperative blood transfusion, sleep disturbance, postoperative visual analog scale, postoperative albumin, smoking, and the appearance of postoperative delirium.

CONCLUSION

The determined risk factors were grouped into preoperative, intraoperative, and postoperative categories substantiated by current data to present instructions for postoperative delirium prevention.

Optimal Timing for Secondary Reconstruction of Head and Neck Defects after Free Flap Failure

BACKGROUND

Finite options exist to address free flap failure. There is a lack of consensus on the standard treatment for secondary reconstruction in such cases. Herein, the authors determined the survival rate of a second flap following a total loss of an initial free flap during head and neck reconstructions and evaluated whether there was a difference in the rate of secondary flap necrosis depending on the timing of reconstruction salvage.

METHODS

The authors retrospectively reviewed 1572 free flaps for head and neck reconstruction from 2010 to 2022. Patients who underwent secondary surgery with flaps after failure of a primary free flap were included. Patients were divided into three groups based on the time for secondary flap reconstruction from the time of primary reconstruction (group A, 0 to 5 days; group B, 6 to 30 days; and group C, >30 days).

RESULTS

The authors identified 64 cases of complete flap loss after primary reconstruction requiring secondary reconstruction. Pedicled flaps were used in 34.4% of the cases, whereas a second free flap was used in 65.6% of the cases. Overall, the flap failure rate for secondary reconstructions was 6.7% in group A, 35.3% in group B, and 6.7% in group C ( P = 0.022). For free tissue transfer, the success rate of a secondary reconstruction was 92.3% in group A, 28.57% in group B, and 93.3% in group C.

CONCLUSIONS

The authors favor an early microsurgical reconstruction (≤5 days) following primary reconstruction in cases of free flap failure. If early reconstruction cannot be performed, a deferred reconstruction with free tissue transfer (>30 days) should be considered.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Does the Anastomosis Recipient Vessel Have an Influence on Free Flap Perfusion in Microvascular Head and Neck Reconstruction-A Retrospective Analysis of 338 Cases with Comparison of Flap Perfusion between Different Arterial and Venous Recipient Vessels in Radial Free Forearm Flaps, Anterolateral Thigh Flaps, and Fibula Free Flaps

Background: Flap perfusion is a prerequisite for microvascular free flap survival and a parameter routinely used for flap monitoring. The aim of this study was to investigate the influence of the anastomosis recipient vessel on flap perfusion. Methods: Flap perfusion was retrospectively analyzed in 338 patients who underwent head and neck reconstruction with microvascular free flaps between 2011 and 2020. The Oxygen-to-see tissue oxygen analysis system measurements for intraoperative and postoperative flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation at 8 and 2 mm tissue depths were compared between arterial anastomosis recipient vessels (external carotid artery [ECA], facial artery [FAA], lingual artery [LIA], and superior thyroid artery [STA]) and venous anastomosis recipient vessels (internal jugular vein [IJV], combination of IJV and IJV branches, IJV branches, and external jugular vein). Results: The postoperative hemoglobin concentration at 2 mm tissue depth differed significantly between arterial anastomosis recipient vessels (ECA, 41.0 arbitrary units [AU]; FAA, 59.0 AU; LIA, 51.5 AU; STA, 59.0 AU; p = 0.029). This difference did not persist in the multivariable testing (p = 0.342). No other differences in flap blood flow, hemoglobin concentration, or hemoglobin oxygen saturation were observed between the arterial and venous anastomosis recipient vessels (p > 0.05 for all). Conclusions: The arterial and venous recipient vessels used for anastomosis did not influence microvascular free flap perfusion. This underlines the capability of the studied recipient vessels to adequately perfuse free flaps, may explain the observed indifferent flap survival rates between commonly used anastomosis recipient vessels, and implies that the recipient vessel is not a confounding variable for flap monitoring with the Oxygen-to-see tissue oxygen analysis system. Further prospective studies are needed to confirm the findings.

Developing Porous Fibrin Scaffolds with Tunable Anisotropic Features to Direct Myoblast Orientation

Functional regeneration of anisotropically aligned tissues such as ligaments, microvascular networks, myocardium, or skeletal muscle requires a temporal and spatial series of biochemical and biophysical cues to direct cell functions that promote native tissue regeneration. When these cues are lost during traumatic injuries such as volumetric muscle loss (VML), scar formation occurs, limiting the regenerative capacity of the tissue. Currently, autologous tissue transfer is the gold standard for treating injuries such as VML but can result in adverse outcomes including graft failure, donor site morbidity, and excessive scarring. Tissue-engineered scaffolds composed of biomaterials, cells, or both have been investigated to promote functional tissue regeneration but are still limited by inadequate tissue ingrowth. These scaffolds should provide precisely tuned topographies and stiffnesses using proregenerative materials to encourage tissue-specific functions such as myoblast orientation, followed by aligned myotube formation and recovery of functional contraction. In this study, we describe the design and characterization of novel porous fibrin scaffolds with anisotropic microarchitectural features that recapitulate the native tissue microenvironment and offer a promising approach for regeneration of aligned tissues. We used directional freeze-casting with varied fibrin concentrations and freezing temperatures to produce scaffolds with tunable degrees of anisotropy and strut widths. Nanoindentation analyses showed that the moduli of our fibrin scaffolds varied as a function of fibrin concentration and were consistent with native skeletal muscle tissue. Quantitative morphometric analyses of myoblast cytoskeletons on scaffold microarchitectures demonstrated enhanced cell alignment as a function of microarchitectural morphology. The ability to precisely control the anisotropic features of fibrin scaffolds promises to provide a powerful tool for directing aligned tissue ingrowth and enhance functional regeneration of tissues such as skeletal muscle.

Pectoralis Major Myofascial (PMMF) Flap as a Valuable Alternative to Microvascular Free Flaps (MFF) in Females with Advanced Oral Squamous Cell Carcinomas: A Retrospective Institutional Analysis

India contributes 60% of HNC cases worldwide among which OSCC has become the most common cancer in males and second most common in females (NCRCR 2020). As most cases present in advanced stage, surgical excision followed by flap reconstruction becomes mandatory to achieve functionality. Due to various logistics and financial issues, microvascular free flap reconstruction is not feasible in every case. Also in females, reconstruction with PMMC is challenging as it violates normal breast contour. As an alternative, we have explored the affectivity of pectoralis major myofascial (PMMF) flaps. A retrospective analysis was undertaken only in female patients with advanced stage oral malignancies who underwent surgery between September 2021 and January 2023. Patients having cutaneous involvement or requiring local flap reconstruction were excluded. Total 43 female patients were included in the study. Among them 8 had Tongue carcinoma and 35 had Alveobuccal carcinoma. 24 patients underwent PMMF reconstruction, whereas 19 patients underwent MFF reconstruction. The complication rates were 12.1% (3 out of 24) in PMMF and 89.4% (17 out of 19 cases)in MFF. Among PMMF group, 1 major complication (death, unrelated to flap) and 2 minor complications (wound infection) occured. Among the MFF group, major complications were e.g. Flap failure requiring re-exploration surgery (n = 4), wound dehiscence (n = 2), bleeding/hematoma (n = 1), donor site complications (n = 6). The minor complications being wound infections (n = 4). The goals of reconstruction of defects in oral cavity cancers are mainly functional and cosmetic integrity. Although MFF's provide a wide range of options for reconstruction of complex defects, as per our study the PMMF flap was more reliable and had lesser complications. PMMF flap is an invaluable alternative to MFF's in female patients for both reconstruction and breast contour preservation.

Management after fibula free flap necrosis in maxillofacial reconstruction

INTRODUCTION

Few articles discuss the management of a free fibula flap (FFF) necrosis in maxillofacial reconstruction.

MATERIAL & METHODS

Between 2005 and 2020, 170 FFF were used for maxillofacial reconstruction at the University Hospital of Caen, among which 16 cases suffered total necrosis and flap removal. The authors categorized these 16 cases into three groups based on the proposed salvage treatment and analyzed the post-operative follow-up, including complications, length of hospital stay and delay in radiotherapy.

RESULTS

In Group A, two patients underwent immediate reconstruction with a new free flap. There were no postoperative complications, and the average hospitalization duration after removal of the first flap was 10 days. In Group B, eleven patients underwent reconstruction with a pedicled musculocutaneous pectoralis major flap. These patients experienced numerous complications, with 73% of them requiring at least one additional surgery, and all of them had an indication for later FFF reconstruction. The average hospitalization duration in this group was 37 days. In Group C, three patients underwent conservative management with debridement and mucosal closure. Two of them experienced complications, and all of them underwent later FFF reconstruction. The average hospitalization duration in this group was 15 days.

DISCUSSION

Based on our experience and the literature review, the use of an immediate new free flap appears to be the best approach after the removal of a FFF. This generates shorter healing times and shorter hospitalization stays, and this allows better results in terms of function and aesthetics. At least, this is the approach that causes the least delay for radiation therapy if indicated. The other approaches should only be proposed in case of patient's poor general condition or in case of refuse of the patient.

Electrically stimulated eccentric contraction training enhances muscle mass, function, and size following volumetric muscle loss

Volumetric muscle loss (VML) overwhelms muscle's innate capacity for repair and can lead to permanent disability. The standard of care for VML injuries includes physical therapy, which can improve muscle function. The objective of this study was to develop and evaluate a rehabilitative therapy using electrically stimulated eccentric contraction training (EST) and determine the structural, biomolecular, and functional response of the VML-injured muscle. This study implemented EST using three different frequencies (50, 100, and 150 Hz) in VML-injured rats starting at 2 weeks postinjury. Four weeks of EST at 150 Hz showed a progressive increase in eccentric torque with an improvement in muscle mass (~39%), myofiber cross-sectional area, and peak isometric torque (~37.5%) relative to the untrained VML-injured sham group. EST at 150 Hz group also increased the number of large type 2B fibers (>5000 µm2 ). Elevated gene expression of markers associated with angiogenesis, myogenesis, neurogenesis, and an anti-inflammatory response was also observed. These results suggest that VML-injured muscles can respond and adapt to eccentric loading. The results of this study may aid in developing physical therapy regimens for traumatized muscles.

Challenging management of an enlarged tracheoesophageal fistula in an irradiated patient

Speech restoration after total laryngectomy may be achieved in different ways, the gold standard being tracheoesophageal puncture (TPE) with the positioning of a speech prosthesis. TPE is not immune to complications, the most common of which being leakage through or around the prosthesis. When dealing with an enlarged tracheoesophageal fistula, the management can be either conservative or surgical. In the following case report, we present a particularly challenging case, in which every conservative strategies failed and a major surgery was required to close the fistula.

Electroconductivity, a regenerative engineering approach to reverse rotator cuff muscle degeneration

Muscle degeneration is one the main factors that lead to the high rate of retear after a successful repair of rotator cuff (RC) tears. The current surgical practices have failed to treat patients with chronic massive rotator cuff tears (RCTs). Therefore, regenerative engineering approaches are being studied to address the challenges. Recent studies showed the promising outcomes of electroactive materials (EAMs) on the regeneration of electrically excitable tissues such as skeletal muscle. Here, we review the most important biological mechanism of RC muscle degeneration. Further, the review covers the recent studies on EAMs for muscle regeneration including RC muscle. Finally, we will discuss the future direction toward the application of EAMs for the augmentation of RCTs.

Evaluation of the diagnostic ability of oral lesions on clinical images among undergraduate dental students

INTRODUCTION

The dentist should be able to carry out systematic oral examinations of the mucosa of patients in order to diagnose any alterations at an early stage.

MATERIALS AND METHODS

An observational, analytical, prospective, and longitudinal study was carried out. 161 students were evaluated at the beginning of their clinical practice in their 4th year of dental school (September 2019), at the beginning and at the end of their 5th year of dental school (June 2021). Thirty oral lesions were projected, and the students were asked to provide an answer; if the lesions were benign, malignant, or potentially malignant, whether they should be biopsied and/or treated and a presumptive diagnosis.

RESULTS

Significant improvement (p < .001) was obtained between the 2019 and 2021 results, in relation to the classification, need for biopsy and treatment of lesions. For differential diagnosis, no significant difference (p = .985) was obtained between the 2019 and 2021 responses. Malignant lesions and PMD obtained mixed results, with the best results corresponding to OSCC.

DISCUSSION

In this study, a correct lesion classification by the students was over 50%. As for the OSCC, the results were superior to the rest of the images, reaching more than 95% correct.

CONCLUSION

Theoretical-practical training from universities and continuing education for graduates in relation to oral mucosal pathologies should be further promoted.

Case report: Ghost cell odontogenic carcinoma in a dog: diagnostics and surgical outcome

A 6 year-old spayed female Poodle presented with a mandibular mass. Radiographic examination revealed osteolysis from the right mandibular canine to the fourth premolar, along with horizontal bone loss and dorsal displacement of the right mandibular first and second premolars. Skull cone beam computed tomography revealed osteolysis at the level of the right mandibular canine and fourth premolar. A destructive bone lesion was observed in the apical area of the right mandibular canine, with mass invasion of the interradicular bone of the right mandibular first molar near the mandibular canal. Consequently, unilateral total mandibulectomy and skin flap surgery were performed. Histopathological examination revealed poorly demarcated and infiltrative neoplastic epithelial cells that formed small islands and trabeculae. Neoplastic cells exhibited the malignant features of cytological atypia and high mitotic activity. Furthermore, the neoplastic epithelial cells frequently showed ghost cell changes and were diagnosed as ghost cell odontogenic carcinoma (GCOC). The dog was followed up for 1 year, during which no severe complications or local recurrence was observed, except for slight mandibular drift, tongue protrusion, and drooling. This case report describes the clinical features, diagnostic imaging, and histologic features of an unreported GCOC in a dog and the favorable outcome following surgical resection.

Enhanced recovery after surgery, current, and future considerations in head and neck cancer

Objectives

Review of the current and relevant literature to develop a list of evidence-based recommendations that can be implemented in head and neck surgical practices. To provide rationale for the multiple aspects of comprehensive care for head and neck surgical patients. To improve postsurgical outcomes for head and neck surgical patients.

Methods

Extensive review of the medical literature was performed and relevant studies in both the head and neck surgery and other surgical specialties were considered for inclusion.

Results

A total of 18 aspects of perioperative care were included in this review. The literature search included 276 publications considered to be the most relevant and up to date evidence. Each topic is concluded with recommendation grade and quality of evidence for the recommendation.

Conclusion

Since it's conception, enhanced recovery after surgery (ERAS) protocols have continued to push for comprehensive and evidence based postsurgical care to improve patient outcomes. Head and neck oncology is one of the newest fields to develop a protocol. Due to the complexity of this patient population and their postsurgical needs, a multidisciplinary approach is needed to facilitate recovery while minimizing complications. Current and future advances in head and neck cancer research will serve to strengthen and add new principles to a comprehensive ERAS protocol.

Level of Evidence

2a.

Harms Reporting in Systematic Reviews of the Microvascular Free Flap in Head and Neck Reconstruction

OBJECTIVE

To evaluate harms reporting in systematic reviews (SRs) of microvascular free flap (MFF) in head and neck reconstruction.

DATA SOURCES

This cross-sectional analysis included searches from the following major databases from 2012 to June 1, 2022: MEDLINE (Pubmed and Ovid), Embase, Epistemonikos, and the Cochrane Database of Systematic Reviews.

REVIEW METHODS

In a masked duplicate manner, screening was performed using Rayyan, and data were extracted using a pilot-tested Google form. A MeaSurement Tool to Assess systematic Reviews-2 (AMSTAR-2) was used to appraise the methodological quality of reviews and the corrected covered area was calculated to detect primary study overlap across all reviews. Reviews were then grouped in pairs of 2, called dyads, and the corrected covered area was calculated again for each individual dyad. Dyads with high overlap (≥50%) were further investigated for the accuracy of harms reporting.

RESULTS

Our initial search yielded 268 records, with 50 SRs meeting the inclusion criteria. A total of 46 (92%) of the included reviews demonstrated 50% or more adherence to the items assessed in our harms checklist. Our corrected covered area tool revealed 0.6% primary study overlap across all reviews, and 1 dyad with high overlap (≥50%). No statistically significant relationship was observed between the completeness of harms reporting and reviews listing harms as a primary outcome, reviews reporting adherence to Preferred Reporting Items of Systematic Reviews and Meta-Analyses, or a review's AMSTAR rating.

CONCLUSION

This study identifies how harms reporting in SRs of MFF reconstruction of the head and neck can be improved and provides suggestions with the potential to mitigate the paucity in current literature.

Analysis of the 100 most cited articles on ameloblastoma

OBJECTIVES

An increasing number of articles are published each year. The aim of this is to provide a list of the 100 most cited articles on the subject of ameloblastoma.

METHODS

A bibliographic search was performed on Google Scholar (GS), Microsoft Academic (MA), and Dimensions for ameloblastoma. A ranking was created in order of citation density. Graphical representations of keywords and authorship were created with VOSviewer. Statistical analysis was performed and only results with a 95% confidence interval were considered significant.

RESULTS

A helpful list of top 100 articles was developed to help professionals in a variety of ways. Some curiosities are discussed about this scientometric analysis in ameloblastoma articles.

CONCLUSIONS

A useful list of the top 100 most cited articles on ameloblastoma has been provided. Bibliometric and altmetric analysis using Google Scholar, Microsoft Academic, and Dimensions is a free and excellent tool, not only as a citation manager but also as a study reference.

Free Tissue Transfer in Head and Neck Reconstruction: A Multidisciplinary 15-Year Experience

BACKGROUND

Free tissue transfer is considered the gold standard in reconstruction of extensive defects in head and neck surgery. The aim of this 15-year retrospective study is to analyze the outcomes of free tissue transfers in the head and neck area in a tertiary referral university hospital.

MATERIALS AND METHODS

A retrospective, single-center study of all patients undergoing free tissue transfers for head and neck reconstruction between 2006 and 2020 was performed. Patient demographics, comorbidities, flap characteristics, outcomes and complications were assessed.

RESULTS

A total of 353 free flaps were performed. The most common defect etiology was synchronous oncologic resection (74.2%). The majority of patients had at least one comorbidity (70.3%), with smoking recorded in 46.2% of the cases and alcohol consumption in 31.7%. The anterolateral thigh flap was the most commonly used flap (37.7%), followed by the osteoseptocutaneous fibula flap (26.9%). Our overall flap success rate was 97.7%, while the overall complication rate was 45.9%.

CONCLUSIONS

Free tissue transfer in head and neck reconstruction is reliable. However, complication rates remain high due to the complexity of such cases and frequent presence of comorbidities. Nonetheless, when effectively managed within a multidisciplinary team, complications rarely jeopardize the overall reconstruction outcome.

Impact of Preemptive Postoperative Pressure Support Ventilation and Physiotherapy on Postoperative Pulmonary Complications after Major Cervicofacial Cancer Surgery: A before and after Study

Introduction: Complex cervicofacial cancer surgery with free flap reconstruction is known to have a high incidence of postoperative pulmonary complications (PPCs). We hypothesized that by implementing an optimized respiratory protocol, including preemptive postoperative pressure support ventilation, physiotherapy, and critical respiratory support and follow-up, we could decrease the incidence of PPCs. Patients and methods: We evaluated the incidence of PPCs over two periods in two groups of patients having a routine or optimized postoperative respiratory protocol: 156 adult patients undergoing major cervicofacial cancer surgery were assessed; 91 were in Group 1 (routine) and 65 were in Group 2 (optimized). In Group 1, no ventilatory support sessions were performed. The incidence of pulmonary complications in both groups was compared using a multivariate analysis. Mortality was also compared until one year postoperatively. Results: In Group 2 with an optimized protocol, the mean number of ventilatory support sessions was 3.7 ± 1 (minimum 2, maximum 6). The incidence of respiratory complications, which was 34% in Group 1 (routine), was reduced by 59% OR = 0.41 (0.16; 0.95), p = 0.043) to 21% for the optimized Group 2. No difference in mortality was found. Conclusions: The present retrospective study showed that using an optimized preemptive respiratory pressure support ventilation combined with physiotherapy after a major cervicofacial surgery could possibly help reduce the incidence of pulmonary complications. Prospective studies are needed to verify these findings.

Superficial Temporal Recipient Vessels for Craniofacial Microvascular Free-Flaps

The selection of recipient vessels for microvascular free-flaps is critical in craniofacial reconstruction. Especially the suitability of the superficial temporal vessels is questioned conflictingly in the literature. The aim of this study was to share our experience with microvascular craniofacial free-flap reconstruction and to evaluate a set of factors that are related to the recipient vessels and to determine how these factors influence flap survival. We conducted a retrospective analysis of 39 free-flaps for craniofacial reconstruction that were performed from 2006 until 2020 and evaluated the indication for microvascular reconstruction, recipient vessels, various factors related to the recipient vessels and complications. The most utilized recipient artery was the facial artery, selected in 20 patients followed by the superficial temporal artery selected in 12 patients. The most commonly used recipient vein was the facial vein used in 16 patients, followed by the superficial temporal vein selected in 10 patients and the external jugular vein in 6 patients. Total flap necrosis occurred in one patient. There was no statistically significant association between the selected recipient vessels and patient comorbidities, major and minor complications, revision of anastomosis or flap loss. The results of our study have demonstrated that the superficial temporal artery and vein show similar results when used for face and scalp reconstruction. Considering their technical and aesthetic advantages they may be the first choice recipient vessels in established free-flap treatment algorithms for craniofacial reconstruction.

Optimizing the Surface Structural and Morphological Properties of Silk Thin Films via Ultra-Short Laser Texturing for Creation of Muscle Cell Matrix Model

Temporary scaffolds that mimic the extracellular matrix’s structure and provide a stable substratum for the natural growth of cells are an innovative trend in the field of tissue engineering. The aim of this study is to obtain and design porous 2D fibroin-based cell matrices by femtosecond laser-induced microstructuring for future applications in muscle tissue engineering. Ultra-fast laser treatment is a non-contact method, which generates controlled porosity—the creation of micro/nanostructures on the surface of the biopolymer that can strongly affect cell behavior, while the control over its surface characteristics has the potential of directing the growth of future muscle tissue in the desired direction. The laser structured 2D thin film matrices from silk were characterized by means of SEM, EDX, AFM, FTIR, Micro-Raman, XRD, and 3D-roughness analyses. A WCA evaluation and initial experiments with murine C2C12 myoblasts cells were also performed. The results show that by varying the laser parameters, a different structuring degree can be achieved through the initial lifting and ejection of the material around the area of laser interaction to generate porous channels with varying widths and depths. The proper optimization of the applied laser parameters can significantly improve the bioactive properties of the investigated 2D model of a muscle cell matrix.

Facilitated harvesting of a radial artery superficial palmar branch flap for reconstruction of moderate finger skin defects

Radial artery superficial palmar branch harvesting is technically challenging, especially for inexperienced hand surgeons. The short pedicle and a damaged recipient digital artery require proximal digital artery dissection and relatively long pedicles. Herein, we describe a facilitated flap elevation technique and its application in various cases. From 2013 to 2021, 10 patients with finger injuries received radial artery superficial palmar flaps. We assessed flap survival, sizes, complications, two-point discrimination, and the Semmes-Weinstein monofilament test results. The main shortcoming of a radial artery superficial palmar flap is its short pedicle. Therefore, we developed a long skin flap design in the long axis direction, and the accompanying vein was dissected proximally to the radial artery to obtain a long pedicle. All flaps survived. The median flap dimension was 5.0 × 2.2 cm (maximum size: 6.0 × 2.0 + 5.0 × 2.0 cm [for a bilobed flap]). While nerve reconstruction was performed in one patient, all patients had preserved sensation. A sufficiently long pedicle can be obtained by dissecting the accompanying vein proximally to the radial artery. Perforators found in the skin around the scaphoid tubercle in all cases suggest value in including this region in flap design. To obtain a longer pedicle, the flap was developed with the long-skin design in the long-axis direction. Although the accompanying vein is usually thin and difficult to anastomose with the finger vein, its proximal dissection led to the accompanying vein of the radial artery that facilitated the harvesting of a sufficiently long vein.

Clinical application and outcomes of reconstructive microsurgery in Africa: A systematic review and meta-analysis

BACKGROUND

Reconstructive microsurgical free flap techniques are often the treatment of choice for a variety of complex tissue defects across multiple surgical specialties. However, the practice is underdeveloped in low- and middle-income countries. The aim of this systematic review was to evaluate the clinical application and outcomes of reconstructive microsurgery performed in Africa.

METHODS

Seven databases (PubMed, Web of Science, MEDLINE, CINAHL, Academic Search Complete, Embase, and Google Scholar) were searched for studies reporting microsurgical procedures performed in Africa. The risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Tools and quality of evidence using the GRADE approach. Meta-analysis was performed using a random effects model to estimate the pooled proportion of events with 95% confidence intervals. The primary outcome was free flap success rate, and the secondary outcomes were the complication and flap salvage rates.

RESULTS

Ninety-two studies were included in the narrative synthesis and nine in the pooled meta-analysis. In total, 1376 free flaps in 1327 patients from 1976 to 2020 were analyzed. Head and neck oncologic reconstruction made up 30% of cases, while breast reconstruction comprised 2%. The pooled flap survival rate was 89% (95% CI: 0.84, 0.93), complication rate 51% (95% CI: 0.36, 0.65), and free flap salvage rate was 45% (95% CI: 0.08, 0.84).

CONCLUSION

This meta-analysis showed that the free flap success rates in Africa are high and comparable to those reported in high-income countries. However, the comparatively higher complication rate and lower salvage rate suggest a need for improved perioperative care.

REVIEW REGISTRATION

Registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 25th September 2020, ID: CRD42020192344.

Prediction of Wound Failure in Patients with Head and Neck Cancer Treated with Free Flap Reconstruction: Utility of CT Perfusion and MR Perfusion in the Early Postoperative Period

BACKGROUND AND PURPOSE

Free flap reconstruction in patients with head and neck cancer carries a risk of postoperative complications, and radiologic predictive factors have been limited. The aim of this study was to assess the factors that predict free flap reconstruction failure using CT and MR perfusion.

MATERIALS AND METHODS

This single-center prospective study included 24 patients (mean age, 62.7 [SD, 9.0] years; 16 men) who had free flap reconstruction from January 2016 to May 2018. CT perfusion and dynamic contrast-enhanced MR imaging with conventional CT and MR imaging were performed between 2 and 4 days after the free flap surgery, and the wound assessments within 14 days after the surgery were conducted by the surgical team. The parameters of CT perfusion and dynamic contrast-enhanced MR imaging with conventional imaging findings and patient demographics were compared between the patients with successful free flap reconstruction and those with wound failure as appropriate. P < .05 was considered significant.

RESULTS

There were 19 patients with successful free flap reconstruction and no wound complications (mean age, 63.9 [SD, 9.5] years; 14 men), while 5 patients had wound failure (mean age, 58.0 [SD, 5.7] years; 2 men). Blood flow, blood volume, MTT, and time maximum intensity projection (P = .007, .007, .015, and .004, respectively) in CT perfusion, and fractional plasma volume, volume transfer constant, peak enhancement, and time to maximum enhancement (P = .006, .039, .004, and .04, respectively) in dynamic contrast-enhanced MR imaging were significantly different between the 2 groups.

CONCLUSIONS

CT perfusion and dynamic contrast-enhanced MR imaging are both promising imaging techniques to predict wound complications after head and neck free flap reconstruction.

Preclinical Development of Bioengineered Allografts Derived from Decellularized Human Diaphragm

Volumetric muscle loss (VML) is the traumatic/surgical loss of skeletal muscle, causing aesthetic damage and functional impairment. Suboptimal current surgical treatments are driving research towards the development of optimised regenerative therapies. The grafting of bioengineered scaffolds derived from decellularized skeletal muscle may be a valid option to promote structural and functional healing. In this work, a cellular human diaphragm was considered as a scaffold material for VML treatment. Decellularization occurred through four detergent-enzymatic protocols involving (1) sodium dodecyl sulfate (SDS), (2) SDS + Tergitol^TM, (3) sodium deoxycholate, and (4) Tergitol^TM. After decellularization, cells, DNA (≤50 ng/mg of tissue), and muscle fibres were efficiently removed, with the preservation of collagen/elastin and 60%–70% of the glycosaminoglycan component. The detergent-enzymatic treatments did not affect the expression of specific extracellular matrix markers (Collagen I and IV, Laminin), while causing the loss of HLA-DR expression to produce non-immunogenic grafts. Adipose-derived stem cells grown by indirect co-culture with decellularized samples maintained 80%–90% viability, demonstrating the biosafety of the scaffolds. Overall, the tested protocols were quite equivalent, with the patches treated by SDS + Tergitol^TM showing better collagen preservation. After subcutaneous implant in Balb/c mice, these acellular diaphragmatic grafts did not elicit a severe immune reaction, integrating with the host tissue.

Laminin-111-Enriched Fibrin Hydrogels Enhance Functional Muscle Regeneration Following Trauma

Volumetric muscle loss (VML) is the surgical or traumatic loss of skeletal muscle, which can cause loss of limb function or permanent disability. VML injuries overwhelms the endogenous regenerative capacity of skeletal muscle and results in poor functional healing outcomes. Currently, there are no approved tissue engineering treatments for VML injuries. In this study, fibrin hydrogels enriched with laminin-111 (LM-111; 50-450 μg/mL) were used for the treatment of VML of the tibialis anterior in a rat model. Treatment with fibrin hydrogel containing 450 μg/mL of LM-111 (FBN450) improved muscle regeneration following VML injury. FBN450 hydrogel treatment increased the relative proportion of contractile to fibrotic tissue as indicated by the myosin: collagen ratio on day 28 post-VML injury. FBN450 hydrogels also enhanced myogenic protein expression and increased the quantity of small to medium size myofibers (500-2000 μm²) as well as innervated myofibers. Improved contractile tissue deposition due to FBN450 hydrogel treatment resulted in a significant improvement (∼60%) in torque production at day 28 postinjury. Taken together, these results suggest that the acellular FBN450 hydrogels provide a promising therapeutic strategy for VML that is worthy of further investigation.

Systemic Inflammatory Markers as Predictors of Postoperative Complications and Survival in Patients With Advanced Head and Neck Squamous Cell Carcinoma Undergoing Free-Flap Reconstruction

PURPOSE

The aim of this study was to determine the prognostic value of systemic inflammatory indices as factors for postoperative complications and survival in patients with advanced stages of p16-negative head and neck squamous cell carcinoma undergoing free-flap reconstruction.

METHODS

This was a retrospective cohort study. The primary predictor variables were inflammatory markers such as neutrophil, lymphocyte, monocyte, and platelet count, neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio, lymphocyte-monocyte ratio, derived NLR, systemic immune-inflammation, and systemic inflammatory marker index (SIM). Multivariate regression analyses were used to measure the associations between systemic inflammatory indices and overall and disease-free survival as a primary outcome and occurrence of postoperative complications as a secondary outcome measure.

RESULTS

The sample was composed of 69 male (76.67%) and 21 female (23.33%) patients, with an average age of 61.15 ± 9.79 years. The median follow-up time was 24 months, and 73 of 91 (66.43%) patients were alive during the median follow-up. Overall disease survival correlated with systemic immune-inflammation (P = .022, cutoff >1,005.3, sensitivity 67.1%, and specificity 70.6%) and SIM (P = .0001, cutoff >4.05, sensitivity 90.4%, and specificity 41.2%), preoperative platelets (P = .036, cutoff <194, sensitivity 28.8%, and specificity 94.1%), and postoperative lymphocytes (P = .012, cutoff <0.6, sensitivity 38%, and specificity 76.5%), whereas increased SIM (P = .042, cutoff >4.05, sensitivity 91.3%, and specificity 38.1%), NLR (P = .031, cutoff >13.2, sensitivity 56.9%, and specificity 60%), and preoperative platelets (P = .006, cutoff <244, sensitivity 52.3%, and specificity 76%) were associated with adverse disease-free survival. The cumulative postoperative complication rate was 34.5%, of which 13.3% accounted for major complications, whereas derived NLR (P = .013, DF 1, χ² test 6.161, cutoff >2.3) and postoperative lymphocytes (P = .009, DF 1, χ² test 6.756, cutoff <1) correlated with occurrence of complications.

CONCLUSIONS

Inflammatory indices as measures of inflammation-related systemic dysfunction may be associated with adverse survival in patients with head and neck squamous cell carcinoma and occurrence of postoperative complications and with specific cutoff values.

Reconstruction of medium-size defects of the oral cavity: radial forearm free flap vs facial artery musculo-mucosal flap

Background

The radial forearm free flap (RFFF) is the most commonly used flap for defects of the oral cavity. The facial artery musculomucosal (FAMM) is a safe and effective method to reconstruct medium sized defects of the oral cavity. No comparison exists between the FAMM flap and RFFF.

Methods

1) Retrospective chart review from 2007 to 2016. 2) Cost difference analysis.

Results

Thirteen FAMM flap cases and 18 RFFF met inclusion criteria. The FAMM flap showed a tendency to lower rates of return to the operating room (p = 0.065) as well as lower rates of complications not requiring return to the OR with 1 complication in 1 patient as opposed to 10 patients with 15 complications (p = 0.008). Also, FAMM flap had shorter operative times compared to the RFFF group (7.2HR and 8.9 HR respectively, p = 0.002). The average operative room related costs for a FAMM flap were 6510 CAD vs 10,703 CAD for RFFF (p < 0.0005). Speech and swallowing outcomes were similar (p > 0.05).

Conclusion

The FAMM flap can be used for reconstruction of medium-size defects of the oral cavity with functional outcomes similar to the RFFF while decreasing the associated costs and morbidity.

Graphical Abstract

Scaffold biomaterials and nano-based therapeutic strategies for skeletal muscle regeneration

Skeletal muscle is integral to the functioning of the human body. Several pathological conditions, such as trauma (primary lesion) or genetic diseases such as Duchenne muscular dystrophy (DMD), can affect and impair its functions or exceed its regeneration capacity. Tissue engineering (TE) based on natural, synthetic and hybrid biomaterials provides a robust platform for developing scaffolds that promote skeletal muscle regeneration, strength recovery, vascularization and innervation. Recent 3D-cell printing technology and the use of nanocarriers for the release of drugs, peptides and antisense oligonucleotides support unique therapeutic alternatives. Here, the authors present recent advances in scaffold biomaterials and nano-based therapeutic strategies for skeletal muscle regeneration and perspectives for future endeavors.

Biomimetic sponges improve muscle structure and function following volumetric muscle loss

Skeletal muscle is inept in regenerating after traumatic injuries such as volumetric muscle loss (VML) due to significant loss of various cellular and acellular components. Currently, there are no approved therapies for the treatment of muscle tissue following trauma. In this study, biomimetic sponges composed of gelatin, collagen, laminin-111, and FK-506 were used for the treatment of VML in a rodent model. We observed that biomimetic sponge treatment improved muscle structure and function while modulating inflammation and limiting the extent of fibrotic tissue deposition. Specifically, sponge treatment increased the total number of myofibers, type 2B fiber cross-sectional area, myosin: collagen ratio, myofibers with central nuclei, and peak isometric torque compared to untreated VML injured muscles. As an acellular scaffold, biomimetic sponges may provide a promising clinical therapy for VML.

Single Versus Double Venous Anastomosis Microvascular Free Flaps for Head and Neck Reconstruction

ABSTRACT

Venous congestion accounts for most microvascular free tissue flaps failures. Given the lack of consensus on the use of single versus dual venous outflow, the authors present our institutional experience with 1 versus 2 vein anastomoses in microvascular free flap for head and neck reconstruction. A retrospective chart review was performed on all patients undergoing free flaps for head and neck reconstruction at our institution between 2008 and 2020. The authors included patients who underwent anterolateral thigh, radial forearm free flap, or fibula free flaps. The authors classified patients based on the number of venous anastomoses used and compared complication rates. A total of 279 patients with a mean age of 55.11 years (standard deviation 19.31) were included. One hundred sixty-eight patients (60.2%) underwent fibula free flaps, 59 (21.1%) anterolateral thigh, and 52 (18.6%) radial forearm free flap. The majority of patients were American Society of Anesthesiologists classification III or higher (N = 158, 56.6%) and had history of radiation (N = 156, 55.9%). Most flaps were performed using a single venous anastomosis (83.8%). Univariate analysis of postoperative outcomes demonstrated no significant differences in overall complications (P = 0.788), flap failure (P = 1.0), return to the Operating Room (OR) (P = 1.0), hematoma (P = 0.225), length of hospital stay (P = 0.725), or venous congestion (P = 0.479). In our cohort, the rate of venous congestion was not statistically different between flaps with 1 and 2 venous anastomoses. Decision to perform a second venous anastomoses should be guided by anatomical location, vessel lie, flap size, and intraoperative visual assessment.

Partition of Pectoralis Major Musculocutaneous Flap as a Salvage Procedure for Simultaneous Coverage of the Exposed Carotid Artery and Reconstruction of Cervical Esophagus

BACKGROUND

In advanced pharyngoesophageal cancer patients, a critical event is represented by the failure of primary reconstruction with exposure of the carotid artery and partial or total defect of the cervical esophagus. For these high-risk patients, a partitioned pectoralis major musculocutaneous (PMMC) flap can prevent carotid blowout and provide skin for simultaneous esophageal reconstruction.

METHODS

Twenty-six patients needing pharyngoesophageal reconstruction together with coverage of carotid artery exposure were included in this retrospective case series. The patients were treated with a partitioned PMMC flap, based on the branching pattern of the pectoral branch of the thoracoacromial artery and the perforators of the pectoralis major muscle, to simultaneously reconstruct the defect and provide coverage for the carotid artery.

RESULTS

In 25 patients, the partitioned PMMC flap reconstructions resulted in complete wound healing without occurrence of carotid blowout syndrome or fistula formation. Minor complications as partial flap necrosis (7.7%) and strictures formation (7.7%) were recorded but did not compromise reconstruction. Twenty-two patients were able to adopt a semisolid diet, and 4 had recurrence of cancer.

CONCLUSIONS

The partitioned PMMC flap reconstruction represents a useful salvage solution to simultaneously restore the continuity of the alimentary tract and provide reliable coverage for the exposed carotid artery.

Management of Flap Failure After Head and Neck Reconstruction: A Systematic Review and Meta-analysis

OBJECTIVE

To systematically review management of flap loss in head and neck construction with free tissue transfer as compared with locoregional flap or conservative management.

DATA SOURCES

Medline, Embase, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and ClinicalTrials.gov were searched up to October 2019.

REVIEW METHODS

Candidate articles were independently reviewed by 2 authors. Articles were considered eligible if they included adequate reporting of flap management after flap loss and outcomes for survival of reconstruction, length of hospitalization, and perioperative complications.

RESULTS

A total of 429 patients had acute flap failure in the perioperative period. The overall success with a secondary free flap was 93% (95% CI, 0.89-0.97; n = 26 studies, I² = 12.8%). There was no difference in hospitalization length after secondary reconstruction between free tissue transfer and locoregional flaps or conservative management (relative risk of hospitalization ≥2 weeks, 96%; 95% CI, 0.80-1.14; n = 3 studies, I² = 0). The pooled relative risk of perioperative complications following free tissue transfer was 0.60 when compared with locoregional flap or conservative management (95% CI, 0.40-0.92; n = 5 studies, I² = 0).

CONCLUSION

Salvage reconstruction with free tissue transfer has a high success rate. Second free flaps following flap failure had a similar length of hospitalization and lower overall complication rate than locoregional reconstruction or conservative management. A second free tissue transfer, when feasible, is likely a more reliable and effective procedure for salvage reconstruction.

Management of two rare cases of dermatofibrosarcoma protuberans arising in the parotid region

Dermatofibrosarcoma protuberans (DFSP) is a rare cutaneous tumour, accounting for less than 1% of malignant tumours of the head and neck region. This tumour rarely presents metastatic disease, but has a high recurrence rate. Therefore, wide surgical excision with microscopically free margins is the therapeutic gold standard. Only five cases are described in literature of this tumour arising in the parotid region, a site that presents challenges both in achieving a wide demolition and in reconstructing the resulting defect. Here we describe two cases of DFSP arising in the parotid region that were treated surgically, achieving microscopically free margins. Reconstruction of the vast skin defect was achieved by means of a supraclavicular artery island flap, with good functional and aesthetic results.

A retrospective study on mandibular reconstruction using iliac crest free flap

PURPOSE

To assess the availability, success rate and complications of microvascular iliac crest free flap for reconstruction of mandibular segmental defects.

METHODS

In this retrospective-descriptive study, we report patients who had undergone segmental mandibular resection for pathologic lesions and received reconstruction with iliac crest microvascular free flap between 2016 and 2019. Clinical and demographic data of all the cases were collected. Success was regarded as complete consolidation of the bone graft in panoramic radiograph. Postoperative complications were defined as major or minor based on the need for intervention. T-test, Kolomogorov_Smirnov, and multivariate analysis were used and the p-value<0.05 was considered to be statistically significant.

RESULTS

Of all 30 patients, 16 were women and 14 were men with an average age of 27.2 years (range 14-40). Patients were followed for 12-60 month (mean: 38.4). One flap was lost due to unsalvageable venous thrombosis. Six other cases had post-op complications while smoking and diabetes were associated with more complications (P = 0.036). Twenty-three patients received primary reconstruction which was more successful than secondary ones (P = 0.003). Osteogenic sarcoma was associated with greater risk of complications (P < 0.01).

CONCLUSIONS

The results of this study suggest that iliac crest microvascular free flap serves as a promising option for the reconstruction of mandibular defects, providing excellent contour and acceptable success rate with low donor site morbidity. Future studies will focus on the role of systemic diseases in post-op complications and flap failures.

Promoting endogenous repair of skeletal muscle using regenerative biomaterials

Skeletal muscles normally have a remarkable ability to repair themselves; however, large muscle injuries and several myopathies diminish this ability leading to permanent loss of function. No clinical therapy yet exists that reliably restores muscle integrity and function following severe injury. Consequently, numerous tissue engineering techniques, both acellular and with cells, are being investigated to enhance muscle regeneration. Biomaterials are an essential part of these techniques as they can present physical and biochemical signals that augment the repair process. Successful tissue engineering strategies require regenerative biomaterials that either actively promote endogenous muscle repair or create an environment supportive of regeneration. This review will discuss several acellular biomaterial strategies for skeletal muscle regeneration with a focus on those under investigation in vivo. This includes materials that release bioactive molecules, biomimetic materials and immunomodulatory materials.

Methacrylic acid-based hydrogels enhance skeletal muscle regeneration after volumetric muscle loss in mice

Volumetric muscle loss (VML) impairs the regenerative ability of skeletal muscle resulting in scar tissue formation and loss of function. Current treatments are of limited efficacy as they do not fully restore function, i.e., force generation. Regenerative biomaterials, such as those containing methacrylic-acid (MAA), are proposed as a novel approach to enhancing muscle regeneration without added cells, growth factors or drugs. Here, the regenerative effects of two hydrogels were investigated: MAA-poly(ethylene glycol) (MAA-PEG) and MAA-collagen. These hydrogels were used to treat VML injuries in murine tibialis anterior muscles. The MAA-collagen hydrogel significantly increased regenerating muscle fiber size and muscle force production. While both hydrogels increased vascularization, only the MAA-collagen hydrogel increased apparent muscle innervation. The MAA-collagen hydrogel also significantly reduced a pro-inflammatory macrophage (MHCII+CD206-) population. Furthermore, the hydrogels had distinct gene expression profiles indicating that their regenerative abilities were carrier dependent. Overall, this study suggests MAA-collagen as a cell-free and drug-free approach to enhancing skeletal muscle regeneration after traumatic injury.

Clinical consequences of head and neck free-flap reconstructions in the DM population

Diabetes mellitus (DM) is a common comorbidity and risk factor for postoperative complications in head and neck (H&N) microsurgical reconstructions. Our study focused on the association between DM and individual complications regarding both surgical and medical aspects. A meta-analysis of English-language articles comparing a series of complications between DM and non-DM H&N free-flap recipients was performed by comprehensive meta-analysis (CMA). Twenty-seven articles presented 14,233 H&N free-flap reconstructions, and a subset of 2329 analyses including diabetic cases was included for final analysis. Total postoperative (RR = 1.194, p < 0.001; OR = 1.506, p = 0.030) and surgical (RR = 1.550, p = 0.001; OR = 3.362, p < 0.001) complications were increased in DM subjects. Free-flap failure/necrosis (RR = 1.577, p = 0.001; OR = 1.999, p = 0.001) and surgical site infections (OR = 2.414, p < 0.001) were also increased in diabetic recipients. However, return to the operating room, dehiscence, fistulas, plate exposures, readmissions, and mortalities were not increased in DM patients. DM increased various complications in H&N free-flap reconstructions. Surgical indications should be cautiously evaluated, and aggressive treatments should be implemented for high-risk recipients.

Perioperative Risk Factors for One-Year Mortality in Patients With Free-Flap Reconstruction Due to Cancer of the Head and Neck

PURPOSE

Head and neck cancer requiring free-flap reconstruction is associated with relatively high mortality. We aimed to evaluate perioperative risk factors for 1-year mortality in this patient group.

METHODS

This is a single-center retrospective analysis of 204 patients operated during 2008 to 2018.

RESULTS

A total of 47 (23.0%) patients died within 1 year. In univariate analysis, there were no differences in the intraoperative course between 1-year survivors and nonsurvivors. Among the 1-year nonsurvivors, preoperative albumin level was lower (39 [36 to 43] vs 42 [39 to 44], P = .032) and the Sequential Organ Failure Assessment admission score was higher (4 [3 to 5] vs 3 [2 to 4], P = .003) than those of the 1-year survivors. Among the nonsurvivors, the preoperative and postoperative levels of leukocytes were higher (7.6 [6.7 to 9.5] vs 6.9 [5.5 to 8.4], P = .002; 11.4 [9.0 to 14.2] vs 8.7 [7.2 to 11.3], P < .001). The highest odds ratios for 1-year mortality in multivariate analysis were American Society of Anesthesiologists A classification greater than 2 (3.9 CI 1.4 to 10.5), male gender (4.0 CI 1.5 to 11), and increase in leukocyte count (1.3 CI 1.1 to 1.5).

CONCLUSIONS

One-year nonsurvivors had higher American Society of Anesthesiologists classification and were more often men. The postoperative inflammatory markers were higher in nonsurvivors, while the intraoperative course did not have a significant impact on the 1-year mortality.

Three salvage strategies in microvascular fibula osteocutaneous flap for mandible reconstruction with vascular compromise and establishment of an algorithm

BACKGROUND

Fibula osteocutaneous flap is associated with a higher rate of reexploration in mandible reconstruction due to limited space for the fixation of various tissue components on multiple segments of the fibula flap. To maintain optimal circulation to the flap and to prevent negative outcomes because of partial or total flap loss, we shared our experiences on salvaging the free fibula flap with vascular compromise in the first reexploration and we developed an algorithm.

METHODS

From 1992 to 2018, 12 patients between the ages of 48 to 63 (mean: 52.5) who had presented with oral squamous cell carcinoma (n = 10) followed by osteoradionecrosis of the mandible (n = 2) were explored. The operative findings were; (1) occlusions of vein (3 cases); (2) occlusions of artery (4 cases); and (3) occlusions of both artery and vein (5 cases). After correcting the kinking or evacuating the hematoma, the arterial inflow was initially reestablished by anterograde flow. If this was nonfunctional, retrograde flow from the distal end of the peroneal artery was provided. For the vein, anterograde venous drainage was reestablished. If the thrombus extended deep into the peroneal vein, regular venous return was blocked on the anterograde side, and the flap remained congested therefore retrograde venous drainage was performed regardless of the valves in the vein. However, the two ends of the peroneal artery were anastomosed to prevent thrombosis of the artery.

RESULTS

The success rate of revised cases was 75% (9/12). All failed cases had presented with both artery and vein occlusion (three cases). Pectoralis major musculocutaneous flap and anterolateral thigh flap were needed for the external surface in two cases. Skin graft was required for seven cases to restore intraoral lining. Six patients underwent dental rehabilitation with prosthetic implants.

CONCLUSION

Immediate reexploration is mandatory to salvage the flap.

Head and neck reconstruction using free flaps: a 30-year medical record review

Background

The free flap surgical method is useful for the reconstruction of head and neck defects. This study retrospectively analyzed the results of head and neck reconstructions using various types of free flaps over the past 30 years.

Methods

Between 1989 and 2018, a total of 866 free flap procedures were performed on 859 patients with head and neck defects, including 7 double free flaps. The causes of vascular crisis and salvage rate were analyzed, and the total flap survival rate calculated among these patients. Additionally, the survival and complication rates for each flap type were compared.

Results

The 866 cases included 557 radial forearm flaps, 200 anterolateral thigh flaps, 39 fibular osteocutaneous flaps, and 70 of various other flaps. The incidence of the vascular crisis was 5.1%; its most common cause was venous thrombosis (52.3%). Salvage surgery was successful in 52.3% of patients, and the total flap survival rate was 97.6%. The success rate of the radial forearm flap was higher than of the anterolateral flap (p<0.01), and the primary sites of malignancy were the tongue, tonsils, and hypopharynx, respectively.

Conclusion

The free flap technique is the most reliable method for head and neck reconstruction; however, the radial forearm free flap showed the highest success rate (98.9%). In patients with malignancy, flap failure was more common in the anterolateral thigh (5.5%) and fibular (5.1%) flaps.

Tissue Engineering in Musculoskeletal Tissue: A Review of the Literature

Tissue engineering refers to the attempt to create functional human tissue from cells in a laboratory. This is a field that uses living cells, biocompatible materials, suitable biochemical and physical factors, and their combinations to create tissue-like structures. To date, no tissue engineered skeletal muscle implants have been developed for clinical use, but they may represent a valid alternative for the treatment of volumetric muscle loss in the near future. Herein, we reviewed the literature and showed different techniques to produce synthetic tissues with the same architectural, structural and functional properties as native tissues.

3D Printing Decellularized Extracellular Matrix to Design Biomimetic Scaffolds for Skeletal Muscle Tissue Engineering

Functional engineered muscles are still a critical clinical issue to be addressed, although different strategies have been considered so far for the treatment of severe muscular injuries. Indeed, the regenerative capacity of skeletal muscle (SM) results inadequate for large-scale defects, and currently, SM reconstruction remains a complex and unsolved task. For this aim, tissue engineered muscles should provide a proper biomimetic extracellular matrix (ECM) alternative, characterized by an aligned/microtopographical structure and a myogenic microenvironment, in order to promote muscle regeneration. As a consequence, both materials and fabrication techniques play a key role to plan an effective therapeutic approach. Tissue-specific decellularized ECM (dECM) seems to be one of the most promising material to support muscle regeneration and repair. 3D printing technologies, on the other side, enable the fabrication of scaffolds with a fine and detailed microarchitecture and patient-specific implants with high structural complexity. To identify innovative biomimetic solutions to develop engineered muscular constructs for the treatment of SM loss, the more recent (last 5 years) reports focused on SM dECM-based scaffolds and 3D printing technologies for SM regeneration are herein reviewed. Possible design inputs for 3D printed SM dECM-based scaffolds for muscular regeneration are also suggested.