Comparison of anterolateral thigh, lateral arm, and parascapular free flaps with regard to donor-site morbidity and aesthetic and functional outcomes. Plast Reconstr Surg. 2013;131:293-302. [PMID: 23357991 DOI: 10.1097/prs.0b013e31827786bc]

Dynamic injectable tissue adhesives with strong adhesion and rapid self-healing for regeneration of large muscle injury

Wounds often necessitate the use of instructive biomaterials to facilitate effective healing. Yet, consistently filling the wound and retaining the material in place presents notable challenges. Here, we develop a new class of injectable tissue adhesives by leveraging the dynamic crosslinking chemistry of Schiff base reactions. These adhesives demonstrate outstanding mechanical properties, especially in regard to stretchability and self-healing capacity, and biodegradability. Furthermore, they also form robust adhesion to biological tissues. Their therapeutic potential was evaluated in a rodent model of volumetric muscle loss (VML). Ultrasound imaging confirmed that the adhesives remained within the wound site, effectively filled the void, and degraded at a rate comparable to the healing process. Histological analysis indicated that the adhesives facilitated muscle fiber and blood vessel formation, and induced anti-inflammatory macrophages. Notably, the injured muscles of mice treated with the adhesives displayed increased weight and higher force generation than the control groups. This approach to adhesive design paves the way for the next generation of medical adhesives in tissue repair.

Free peroneal artery perforator flap for reconstruction of traumatic limb soft tissue defects: A retrospective case series study

BACKGROUND

The free peroneal artery perforator (FPAP) flap is used for soft tissue defects after burns and trauma. However, the use of FPAP flaps to repair limb soft tissue defects for immediate reconstruction was rarely reported previously. Therefore, the purpose of this report is to evaluate free peroneal artery perforator flap to reconstruct traumatic limb soft tissue defects for immediate reconstruction.

PATIENTS AND METHODS

A total of 25 cases of limb soft tissue defects undergoing immediate reconstruction of FPAP flap transfer were retrospectively evaluated from January 2019 to June 2019 in our institute. The locations of defects included the palm (10 cases), finger (5 cases), foot (7 cases), ankle (2 cases) and wrist (1 case). The sizes of defect varied from 3 × 2 cm to 15 × 7 cm (54.1 cm2 in average). Flaps were harvested based on the peroneal perforator vessels, initially marked using hand-held Doppler.

RESULTS

Average size of harvested flap was 9.7 × 6.2 cm (ranging from 3.5 × 2 cm to 16 × 8 cm). All perforators were harvested from the peroneal artery and the arterial diameter ranged from 0.8 to 1.7 mm. The average pedicle length was 3.04 cm (range, 1.85-4.75 cm). Five vascular thrombosis were found including three cases of arterial thrombosis and two cases of venous thrombosis which were successfully salvaged by re-operation and vein graft. Satisfying functional outcome and acceptable appearance were achieved at 6 months or longer after surgery (range, 6-15 months, 12 months in average). All flaps survived at the end-point.

CONCLUSIONS

The FPAP flap is a reliable and thin fasciocutaneous flap, which can be used for repairing limb soft tissue defects. The FPAP flap can be used for covering defects with various appearances, locations, and sizes.

The contribution of microvascular free flaps and pedicled flaps to successful chest wall surgery

OBJECTIVE

Pedicled flaps (PFs) have historically served as the preferred option for reconstruction of large chest wall defects. More recently, the indications for microvascular-free flaps (MVFFs) have increased, particularly for defects in which PFs are inadequate or unavailable. We sought to compare oncologic and surgical outcomes between MVFFs and PFs in reconstructions of full-thickness chest wall defects.

METHODS

We retrospectively identified all patients who underwent chest wall resection at our institution from 2000 to 2022. Patients were stratified by flap reconstruction. End points were defect size, rate of complete resection, rate of local recurrence, and postoperative outcomes. Multivariable analysis was performed to identify factors associated with complications at 30 days.

RESULTS

In total, 536 patients underwent chest wall resection, of whom 133 had flap reconstruction (MVFF, n = 28; PF, n = 105). The median (interquartile range) covered defect size was 172 cm2 (100-216 cm2) for patients receiving MVFF versus 109 cm2 (75-148 cm2) for patients receiving PF (P = .004). The rate of R0 resection was high in both groups (MVFF, 93% [n = 26]; PF, 86% [n = 90]; P = .5). The rate of local recurrence was 4% in MVFF patients (n = 1) versus 12% in PF patients (n = 13, P = .3). Postoperative complications were not statistically different between groups (odds ratio for PF, 1.37; 95% confidence interval, 0.39-5.14]; P = .6). Operative time >400 minutes was associated with 30-day complications (odds ratio, 3.22; 95% confidence interval, 1.10-9.93; P = .033).

CONCLUSIONS

Patients with MVFFs had larger defects, a high rate of complete resection, and a low rate of local recurrence. MVFFs are a valid option for chest wall reconstructions.

Comparison of Antero-Lateral Thigh Flap and Vastus Lateralis Muscle Flap for the Treatment of Extensive Scalp Defects-A Retrospective Cohort Study

Free flap reconstruction is the standard of care for extensive defects of the head and neck area. In this study, two types of free flaps, the antero-lateral thigh flap (ALT) and the vastus lateralis muscle flap, were compared. The primary endpoint was flap success, secondary endpoints were complication rates, hospitalization and surgery time. Cases with defect situations of the scalp and consecutive microvascular free flap reconstructions using either ALT flaps or vastus lateralis muscle flaps between 2014 and 2022 were retrospectively analyzed. Indications, perioperative handling and outcomes were compared. Twenty patients were included in the analysis. Ten patients (50%) received a free flap reconstruction using an ALT flap and ten patients (50%) received a vastus lateralis flap. A simultaneous two-team approach was possible in each case and the flap success rate was 100% with the need for one successful anastomosis revision. The mean defect size in our cohort was 147 ± 46 cm2. There were no significant differences in surgery time, duration of hospitalization or complication rate between both cohorts. Both free flaps, the ALT and the vastus lateralis flap, are suitable for the closure of large scalp defects. They provide high success rates, short surgery times without the need for patient repositioning and low donor-site morbidity. The vastus lateralis muscle flap bares the advantage of being perforator-independent and allows for the preparation of long vessels for anastomosis if needed while baring the disadvantage of a prolonged period of healing via granulation or the need for secondary surgery in terms of covering by split-thickness skin grafts which may interfere with necessary adjuvant treatment in oncological patients.

Nanoenzyme-Reinforced Multifunctional Scaffold Based on Ti3C2Tx MXene Nanosheets for Promoting Structure-Functional Skeletal Muscle Regeneration via Electroactivity and Microenvironment Management

The completed volumetric muscle loss (VML) regeneration remains a challenge due to the limited myogenic differentiation as well as the oxidative, inflammatory, and hypoxic microenvironment. Herein, a 2D Ti3C2Tx MXene@MnO2 nanocomposite with conductivity and microenvironment remodeling was fabricated and applied in developing a multifunctional hydrogel (FME) scaffold to simultaneously conquer these hurdles. Among them, Ti3C2Tx MXene with electroconductive ability remarkably promotes myogenic differentiation via enhancing the myotube formation and upregulating the relative expression of the myosin heavy chain (MHC) protein and myogenic genes (MyoD and MyoG) in myogenesis. The MnO2 nanoenzyme-reinforced Ti3C2Tx MXene significantly reshapes the hostile microenvironment by eliminating reactive oxygen species (ROS), regulating macrophage polarization from M1 to M2 and continuously supplying O2. Together, the FME hydrogel as a bioactive multifunctional scaffold significantly accelerates structure-functional VML regeneration in vivo and represents a multipronged strategy for the VML regeneration via electroactivity and microenvironment management.

Combinatorial extracellular matrix cues with mechanical strain induce differential effects on myogenesis in vitro

Skeletal muscle regeneration remains a clinical unmet need for volumetric muscle loss and atrophy where muscle function cannot be restored to prior capacity. Current experimental approaches do not account for the complex microenvironmental factors that modulate myogenesis. In this study we developed a biomimetic tissue chip platform to systematically study the combined effects of the extracellular matrix (ECM) microenvironment and mechanical strain on myogenesis of murine myoblasts. Using stretchable tissue chips composed of collagen I (C), fibronectin (F) and laminin (L), as well as their combinations thereof, we tested the addition of mechanical strain regimens on myogenesis at the transcriptomic and translational levels. Our results show that ECMs have a significant effect on myotube formation in C2C12 murine myoblasts. Under static conditions, laminin substrates induced the longest myotubes, whereas fibronectin produced the widest myotubes. Combinatorial ECMs showed non-intuitive effects on myotube formation. Genome-wide analysis revealed the upregulation in actin cytoskeletal related genes that are suggestive of myogenesis. When mechanical strain was introduced to C + F + L combinatorial ECM substrates in the form of constant or intermittent uniaxial strain at low (5%) and high (15%) levels, we observed synergistic enhancements in myotube width, along with transcriptomic upregulation in myosin heavy chain genes. Together, these studies highlight the complex role of microenvironmental factors such as ECM interactions and strain on myotube formation and the underlying signaling pathways.

Anterolateral Thigh Free Flap Versus Thigh Split Thickness Skin Graft: Comparison of Morbidity in the First 30 Days

Background: An anterior thigh split thickness skin graft (AT-STSG) is frequently needed to close the radial forearm free flap (RFFF) donor site, conferring morbidity to two extremities. The anterolateral thigh (ALT) free flap is virtually always closed primarily. Objective: To compare donor site pain, sensation, motor function, and cosmesis associated with the AT-STSG and the ALT. Methods: Patients undergoing an ALT or an RFFF with AT-STSG were enrolled in a prospective observational cohort study. Pain, tingling, numbness, lower extremity function, and subjective donor site cosmetic satisfaction were measured at 1 week and 1 month postoperation using validated instruments. Results: Forty-eight patients were included, with a mean age of 64.2 years (female 31.2%). There were no differences in age or medical comorbidities between the two groups. The average donor defect was 50 and 180 cm² for the AT-STSG and ALT cohorts, respectively. At 1 week and 1 month postoperatively, we did not detect a difference in donor site pain, pruritus, numbness or tingling, lower extremity function, or subjective cosmetic satisfaction between the two cohorts. Conclusion: ALT primary donor site morbidity, including pain, sensory function, motor function, and cosmesis, is equivalent to RFFF secondary donor site morbidity at 1 week and 1 month postoperatively.

How to measure success in lower extremity reconstruction, which outcome measurements do we use a systematic review and metanalysis

Different factors have to be considered and weighted in the treatment algorithm of lower extremity reconstruction. A combination of both clinicians' and patients' perspectives is necessary to provide a conclusive picture. Currently, there aren't any standardized and validated measurement data sets for lower extremity reconstructions. This makes it necessary to identify the relevant domains. We, therefore, performed a systematic review and metanalysis of outcome measurements and evaluated their ability to measure outcomes after lower extremity reconstruction. A systematic review and metanalysis according to the 'Preferred Reporting Items for Systematic Reviews and Meta-Analyses' protocol were performed for studies reporting at least one structured outcome measurement of lower extremity reconstruction. Both Patient (PROMs)- and Clinician reported outcome measurements (CROMs)were analyzed. Of the 2827 identified articles, 102 were included in the final analysis. In total 86 outcome measurements were identified, 34 CROMs, 44 PROMs and 8 (9.3%) outcome measurements that have elements of both. Twenty-four measure functional outcome, 3 pain, 10 sensations and proprioception, 9 quality of life, 8 satisfaction with the result, 5 measure the aesthetic outcome, 6 contours and flap stability and 21 contain multidomain elements. A multitude of different outcome measurements is currently used in lower extremity reconstruction So far, no consensus has been reached on what to measure and how. Validation and standardization of both PROMs and CROMs in plastic surgery is needed to improve the outcome of our patients, better meet their needs and expectations and eventually optimize extremity reconstruction by enabling a direct comparison of studies' results.

Flap Debulking and Secondary Revisions in Head and Neck Reconstruction: A Systematic Review with Clinical Applications

Flap debulking and secondary revisions are an integral factor in providing optimum outcomes to reconstructive patients. This review article summarizes systematically the available literature on flap debulking in head and neck reconstruction. The clinical applications of debulking techniques are discussed, including fractional direct excision, liposuction, and single-stage excision or planning with skin grafting. New technologies are also discussed.

Multiple simultaneous free flaps for head and neck reconstruction: A multi-institutional cohort

OBJECTIVES

To describe the experience of two tertiary academic centers with multiple, simultaneous free flaps for complex head and neck defect reconstruction.

METHODS

Patients undergoing multiple, simultaneous free flaps from 2017 to 2022 were retrospectively reviewed.

RESULTS

Seventy-one patients (64.8% male, median age 61 years) were identified and underwent 143 free flaps. The leading surgical indication was squamous cell carcinoma (n = 48, 67.6%). Defect sites included oral cavity, maxilla, pharynx, parotid, skull base, and scalp. The most common free flap combinations were fibula (FFF) with anterolateral thigh flap (n = 33, 46.5%), radial forearm (RFFF) with scapula (n = 11, 15.5%), and RFFF with FFF (n = 10, 14.1%). Median operative time was 12 h. Median length of hospitalization was 10 days. At last follow-up (median 6 months), 141 flaps (98.6%) survived without partial nor complete flap failure.

CONCLUSION

Multiple, simultaneous free flaps are a rare, yet reliable option for head and neck reconstruction in select patients with defects involving several tissue types, multiple functional areas, or large volumes.

Injectable conductive micro-cryogel as a muscle stem cell carrier improves myogenic proliferation, differentiation and in situ skeletal muscle regeneration

Volumetric muscle loss (VML) results in the impediment of skeletal muscle function, and there were still great challenges in cell delivery approach with the minimally invasive operation to repair muscle defects. To deliver cells to the VML defects site efficiently, the injectable conductive porous nanocomposite microcryogels based on gelatin (GT) and reduced graphene oxide (rGO) were designed and prepared. The microcryogels were loaded with myoblasts to form an injectable cell delivery system and show the ability to protect cells during injection. Conductive microcryogel with 4 mg/mL rGO (GT/rGO4) enhanced C2C12 cell proliferation and myogenic differentiation during 3D culture compared with pure gelatin microcryogel. In a mice VML model, injection of microcryogel loaded with muscle-derived stem cells into the injury site significantly improved the generation of new muscle fibers and blood vessels, and anti-inflammatory properties. The results show that injectable biodegradable conductive microcryogel can be used as myoblast cell carriers with the potential to maintain cell activity and deliver cells to defective sites, thereby in situ enhancing skeletal muscle regeneration. STATEMENT OF SIGNIFICANCE: Volumetric muscle loss overwhelms the regenerative capacity of skeletal muscle, which results in severe damage to muscle tissues. In the treatment of volumetric muscle loss, conductive niche and muscle stem cells are needed to alleviate excessive scar formation and inflammation to improve muscle regeneration. Injectable gelatin/reduced graphene oxide based nanocomposite microcryogel can enhance the differentiation of seeded muscle stem cells. The improved repair of volumetric muscle loss was achieved via reducing collagen deposition and inflammation in the injected region through the microcryogel cell-delivery therapy, suggesting great potential of the injectable microcryogel as a cell carrier in soft tissue repair.

Development of a mathematical formula and online tool to calculate the potential maximum flap width to allow for primary anterolateral thigh donor-site closure in Caucasians

BACKGROUND

Primary anterolateral thigh (ALT) flap donor-site closure is crucial to achieve patient satisfaction, avoid burdensome secondary surgeries, and avert poor outcomes. Only vague maximum flap width recommendations have been suggested, which fall short of acknowledging individual patient habitus and thigh morphology. Therefore, we aimed at identifying a user-friendly preoperative calculation of maximum flap width for primary closure.

METHODS

A total of 429 ALT free flaps performed between 2009 and 2020 were analyzed. A total of 350 donor-sites were closed primarily (82%) and 79 (18%) were split-thickness skin-grafted (STSG). Patient demographics including sex, age, and BMI, operative details, and flap characteristics were compared to assess their impact on the outcome variable. Receiver operating characteristic (ROC) curves were plotted for all significant predictors discriminating between closure and STSG. Areas under the curve (AUCs) were calculated for each parameter combination and optimal cutoffs were determined using Youden's Index.

RESULTS

Sex, age, BMI, and flap width alone were poor discriminators. Dividing flap width by BMI and logarithmized BMI yielded AUCs of 0.91 and 0.94, respectively. Including patient sex yielded the best fitting regression model (χ²  = 251.939, p < .0001) increasing the AUC to 0.96 (95% CI: 0.93-0.98, p < .0001). The optimal cutoff value discriminated between primary closure and STSG with 90% sensitivity and 89% specificity. An online calculator of patient-individual maximum ALT width was then programmed.

CONCLUSIONS

Sex and BMI are reliable predictors of successful primary ALT donor-site closure in Caucasians. We devised a novel formula for calculating patient-individual maximum ALT widths preoperatively, predicting failure of primary closure with 90% sensitivity in our cohort, available at: https://kitteltaschenbuch.com/altwidth/calculate.htm.

Chest wall reconstruction in a young man after high-velocity gunshot using a combination latissimus dorsi flaps and titanium plates: A case report

Chest trauma, penetrating or blunt, is common in this era of road traffic accidents, terrorism, and hunting in Iraq. During the last decade, many novel surgical procedures and materials were used to reconstruct or stabilize the chest wall to improve integration, maintain the stability of the chest wall, and reduce infections. However, no precise guidelines for managing chest wall diseases are still available to date. Here, we present a 24-year-old male who underwent chest wall reconstruction using a combination of latissimus dorsi flap and titanium plates, which were to cover the chest wall after a high-velocity gunshot. This patient was in shock too, with a lung contusion and massive hemorrhage. The sucking open chest wound lead to grossly disturbed respiratory mechanics. Such patients usually die on the way due to hemodynamic instability. In this particular case, adequate resuscitation and prompt thoracotomy saved the patient's life. This case report is important because, as we already mentioned, thoracic trauma alone is the cause of death in 25% of patients, and in another 25%, it's a contributing factor in a polytrauma death. This amounts to very high mortality. Our patient received a major laceration of the left lung. Our patient had a full recovery from this life-threatening situation.

Comparative Effects of Basic Fibroblast Growth Factor Delivery or Voluntary Exercise on Muscle Regeneration after Volumetric Muscle Loss

Volumetric muscle loss (VML) is associated with irreversibly impaired muscle function due to traumatic injury. Experimental approaches to treat VML include the delivery of basic fibroblast growth factor (bFGF) or rehabilitative exercise. The objective of this study was to compare the effects of spatially nanopatterned collagen scaffold implants with either bFGF delivery or in conjunction with voluntary exercise. Aligned nanofibrillar collagen scaffold bundles were adsorbed with bFGF, and the bioactivity of bFGF-laden scaffolds was examined by skeletal myoblast or endothelial cell proliferation. The therapeutic efficacy of scaffold implants with either bFGF release or exercise was examined in a murine VML model. Our results show an initial burst release of bFGF from the scaffolds, followed by a slower release over 21 days. The released bFGF induced myoblast and endothelial cell proliferation in vitro. After 3 weeks of implantation in a mouse VML model, twitch force generation was significantly higher in mice treated with bFGF-laden scaffolds compared to bFGF-laden scaffolds with exercise. However, myofiber density was not significantly improved with bFGF scaffolds or voluntary exercise. In contrast, the scaffold implant with exercise induced more re-innervation than all other groups. These results highlight the differential effects of bFGF and exercise on muscle regeneration.

A single-center retrospective comparison of Duplex ultrasonography versus audible Doppler regarding anterolateral thigh perforator flap harvest and operative times

INTRODUCTION

We reported on the superiority of preoperative Duplex mapping ("Duplex") over audible Dopplers ("Doppler") in anterolateral thigh perforator (ALT) free flaps for upper extremity reconstruction. To corroborate our findings on a larger cohort, we conducted this present study focusing on surgical efficiency and patient safety.

METHODS

150 consecutive ALT free flaps were divided into 65 cases of preoperative Duplex versus 85 Doppler controls. We first compared patient demographics, operative details, and defect and flap characteristics. We then assessed group differences in the number and course of perforators pursued intraoperatively, flap harvest and operative times, and donor-site complications. Additionally, the impact of the training level of the primary microsurgeon was evaluated.

RESULTS

Cases and controls were comparable regarding age (p = .48), sex (p = .81), ASA class (p = .48), and BMI (p = .90). Duplex was associated with an increased likelihood of raising flaps on one single dominant perforator of purely septal course and significant reductions of flap harvest (68 ± 10 min, p < .0001) and operative times (74 ± 16 min, p < .0001), regardless of the experience of the primary microsurgeon. There were strong negative linear correlations between preoperative Duplex and both the flap harvest and operative times (p < .0001). Additionally, while there was no effect on the emergency take-back rate (OR = 1.3, p = .60), revisions were significantly less likely among duplexed patients (OR = 0.15, p = .04).

CONCLUSIONS

Preoperative Duplex is associated with a significant reduction in ALT free flap harvest and overall operative times, as well as donor-site revisions as opposed to Doppler planning, regardless of the training level of the primary microsurgeon.

Temporoparietal Fascial Free Flap: A Systematic Review

ABSTRACT

The temporoparietal fascial flap (TPFF) is a versatile tool used in head and neck reconstructive surgeries as well as distal upper and lower extremity reconstructions. Depending on the anatomical location and characteristics of the recipient site soft tissue defects, harvesting techniques for TPFF retrieval may include elevation as a pedicle or a free flap, inclusion of the temporalis muscle and/or adjacent calvarial bone as a composite flap. The TPFF as a free flap is not only used for soft tissue coverage of various defects, and it can be used as a joint gliding surface with coverage of nerve and tendons after repair or trauma. This article includes a systematic search of the medical literature for indications, historical background, techniques, current perspective, and complications along with the pros and cons of the free TPFF compared with other potential reconstructive options.

Free vascularized parascapular fat flap for parotidectomy reconstruction

OBJECTIVE

The contour defect resulting after parotidectomy can be cosmetically unappealing. Multiple reconstructive efforts have been reported to mitigate this problem. We describe a novel technique of vascularized parascapular fat reconstruction based on the circumflex scapular vessels and evaluate its outcomes.

METHODS

Consecutive patients who underwent parotidectomy with or without additional resections and vascularized parascapular fat flap reconstruction in 2020 were included. Demographic, morphologic, intraoperative, and postoperative data were assessed.

RESULTS

Eight patients (3 female) were included. Median cut-to-close time was 247 (range 209-298) minutes, including tumor ablation. None of the patients had any wound complications, and all except one was discharged on postoperative day 1. Flap monitoring was not performed. None reported any significant donor site morbidity except scar formation. At last follow up, all patients reported satisfactory facial contour.

CONCLUSION

Vascularized parascapular fat flap reconstruction of parotidectomy contour defects has satisfactory cosmetic outcomes with minimal morbidity and short hospitalization courses.

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.

Engineering skeletal muscle: Building complexity to achieve functionality

Volumetric muscle loss (VML) VML is defined as the loss of a critical mass of skeletal muscle that overwhelms the muscle's natural healing mechanisms, leaving patients with permanent functional deficits and deformity. The treatment of these defects is complex, as skeletal muscle is a composite structure that relies closely on the action of supporting tissues such as tendons, vasculature, nerves, and bone. The gold standard of treatment for VML injuries, an autologous muscle flap transfer, suffers from many shortcomings but nevertheless remains the best clinically available avenue to restore function. This review will consider the use of composite tissue engineered constructs, with multiple components that act together to replicate the function of an intact muscle, as an alternative to autologous muscle flaps. We will discuss recent advances in the field of tissue engineering that enable skeletal muscle constructs to more closely reproduce the functionality of an autologous muscle flap by incorporating vasculature, promoting innervation, and reconstructing the muscle-tendon boundary. Additionally, our understanding of the cellular composition of skeletal muscle has evolved to recognize the importance of a diverse variety of cell types in muscle regeneration, including fibro/adipogenic progenitors and immune cells like macrophages and regulatory T cells. We will address recent advances in our understanding of how these cell types interact with, and can be incorporated into, implanted tissue engineered constructs.

Targeting intramuscular adipose tissue expansion to preserve contractile function in volumetric muscle loss: A potentially novel therapy?

In volumetric muscle loss (VML), the severity of trauma exceeds a muscle's regenerative capacity. VML causes permanent functional impairments for which there are no rehabilitative, pharmacological, or regenerative medicine interventions. Driving failed regeneration in VML is a hostile microenvironment characterized by heightened inflammation, fibrosis, and denervation, which may reduce the remaining muscle tissue's quality, and stimulate intramuscular adipose tissue (IMAT) expansion. IMAT is increased in various muscle disease states, and has known lipotoxic effects on regeneration and contractile function. The contribution of ectopic fat deposition to the hostile VML microenvironment at the injury site and in the remaining tissue warrants further investigation. Targeting IMAT may lead to novel therapeutic strategies for improving functional outcomes in VML.

Innovative chest wall reconstruction with a locking plate and cement spacer after radical resection of chondrosarcoma in the sternum: A case report

BACKGROUND

Chondrosarcoma, a cartilage matrix producing tumor, is the second most commonly observed primary bone tumor after osteosarcoma, accounting for 15% of all chest wall malignancies. We herein report the case of a patient with chondrosarcoma of the sternum and our management of the chest wall defects that presented following radical tumor resection.

CASE SUMMARY

A 31-year-old patient presented to our hospital with dull pain and a protruding mass overlying the chest for 3 mo. The presence of nocturnal pain and mass size progression was reported, as were overhead arm elevation-related limitations. Computed tomography showed a focal osteoblastic mass in the sternum with bony exostosis and adjacent soft tissue calcification. Positron emission tomography-computed tomography revealed hypermetabolic activity with a mass located over the upper sternum. Magnetic resonance imaging showed a focal ill-defined bony mass of the sternum with cortical destruction and periosteal reaction. Preoperative biopsy showed a consistent result with chondrosarcoma with immunohistochemical positivity for S100 and focal positivity for IDH-1. The grade II chondrosarcoma diagnosis was confirmed by postoperative pathology. The patient underwent radical tumor resection and chest wall reconstruction with a locking plate and cement spacer. The patient was discharged 1 wk after surgery without any complications. At the 1-year follow-up, there was no local recurrence on imaging. The functional scores, including Constant Score, Nottingham Clavicle Score, and Oxford Shoulder Score, showed the absence of pain in the performance of daily activities or substantial functional disabilities.

CONCLUSION

The diagnosis of chondrosarcoma must be considered when chest wall tumors are encountered. The surgical reconstructive materials, with a locking plate and cement spacer, used in our study are cost-effective and readily-available for the sternum defect.

RECONSTRUCTION OF UPPER LIMB SOFT TISSUE INJURIES, EXCEPT FOR FINGERTIPS LESIONS

Objective:

The main purpose of this work was to evaluate the advantages and disadvantages of reconstructive procedures applied in upper limb soft tissue injuries according to their location.

Methods:

The study involved 94 male and 22 female patients (116 total) operated between April 2001 and November 2017 due to traumatic injuries in a upper limb. Individuals were evaluated considering their age, sex, etiology, reconstruction area , applied methodology and complications. The finger injuries were excluded.

Results:

The performed reconstruction procedures include 29 skin grafts; six advancement flaps; seven rotation flaps; 33 pedicled fasciocutaneous flaps, 9 free fasciocutaneous flaps; 5 pedicled muscle flaps; 12 free muscle flaps, three pedicled musculocutaneous flaps; one free musculocutaneous flap; 11 neurovascular free flaps.

Conclusion:

Reconstructive procedures in the upper limbs are diverse, varying from skin grafting to free flaps. The indication of the best option depends on the type of injurie and the surgeon. The final goal is to reach the best functional result combined with the lowest possible morbidity. Level of Evidence IV, Case series.

Reconstruction of Extensive Soft Tissue Defects of Lower Extremity With the Extended Anterolateral Thigh Flap

The anterolateral thigh flap is a classic flap used for various reconstruction defects. However, the flap viability of extended large skin paddles (ie, 240 cm²) was doubted by many surgeons. This study reports successful experience of reconstructing extensive soft tissue defects of lower extremity using extended large skin paddles. Twelve consecutive patients who had undergone reconstruction of defects using an extended anterolateral thigh flap were identified. Patient characteristics (age, sex, defect location, injured structures, and type of flap) and outcome data were analyzed retrospectively. One artery and 2 accompanying veins were anastomosed to vascularize each flap. Follow-up periods ranged from 10 to 91 months postoperatively. The average size of the flaps was 268.75 cm² (range = 220-391 cm²). All flaps were perforator flaps with one perforator except that 2 perforators were used in 3 patients. Two patients suffered partial flap necrosis of the distal portion with delayed healing. In conclusion, the extended anterolateral thigh flap is a considerable option for massive defects requiring composite tissue coverage. This flap is advantageous for reconstructing various complex defects in the lower extremities, providing a pliable and vascularized tissue to cover exposed extensive defects including tendons, nerves, and bones.

Lateral Arm Flap: Its Usage as Pedicle and Free Flap

Introduction

The lateral arm flap is an excellent flap for both local and microvascular reconstruction. For local reconstruction on the upper extremity or as a distant microvascular flap, its advantages include short operation time, thin pliable tissue, non-dominant vessel, and minimal donor site morbidity. Moreover, it fulfills the goal of optimal reconstruction of form, function, and aesthetics. The objective is to share our experience of using the lateral arm flap, both as a free flap and as a pedicled flap.

Methods

After taking exemption from the ethical review committee (ERC) of Aga Khan University Hospital, a retrospective data analysis of patients who had undergone lateral arm flap at the Plastic and Reconstructive Surgery department of the Aga Khan University Hospital was carried out from January 2012 to December 2019. The data examined included the patient's age, gender, diagnosis, location of the defect, size of the flap, and outcome of the flap at three weeks post-operation. For free flaps, data of the recipient artery used for anastomosis and the number of veins anastomosed were also included.

Results

Over a period of eight years, 33 lateral arm flaps were performed, including 23 free flaps and 10 pedicled flaps. The average size of the free flap was 12x6 cm and that of the pedicled flap was 8x5 cm. In the free-flap group, there was a failure in three flaps, two of which were due to arterial anastomosis in the zone of injury. There were no failures in the pedicled flap group.

Conclusion

The lateral arm flap is a reliable flap, with consistent anatomy, which can be used for coverage in different parts of the body.

Comparison of patients satisfaction with aesthetic outcomes following lower extremity reconstruction: Muscle vs. fasciocutaneous free flaps

BACKGROUND

The microsurgical reconstruction of complex lower limb defects has become a routine procedure with high success rates. The emphasis has changed from ensuring flap 'success' to providing a reconstruction, which is also aesthetically pleasing. The aim of this study was to compare patients' satisfaction with aesthetic outcomes, following muscle or fasciocutaneous free flap reconstruction to the lower limb.

METHODS

Data were collected retrospectively between July, 2013 and May, 2018 at a single institution. The inclusion criteria were adult patients who had successful free tissue transfers to the lower limb following any aetiology. A Likert Scale questionnaire was sent to all patients who met these criteria. The questionnaire included questions related to the reconstruction and donor site.

RESULTS

Questionnaires were sent to 83 patients who met the inclusion criteria. Forty-seven (57%) patients responded, of which 22 (47%) underwent reconstruction with muscular flap and 25 (53%) with fasciocutaneous flap. A statistically significant difference between the two groups was found in relation to flap texture (p = 0.003). Patients with fasciocutaneous flap reconstruction being more satisfied. No significant difference was observed for contour, similarity to the contralateral side, bulkiness of flap, colour match, scar, or overall appearance. The comparison of donor site results revealed no significant difference between the two groups CONCLUSIONS: Despite increase in success in lower extremity reconstruction, many patients still find aesthetic results suboptimal and this affects an individual's global sense of well-being. Aesthetic restoration should be viewed as an integral part of lower limb reconstruction.

LEVEL OF EVIDENCE

Therapeutic, III.

Evaluation of the Therapeutic Potential of Human iPSCs in a Murine Model of VML

Volumetric muscle loss injury is a common health problem with long-term disabilities. One common treatment is using muscle flaps from donor site, which has limited potentials due to donor site availability and morbidity. Although several stem cell therapies have been evaluated so far, most suffer from limited availability, immune incompatibility, or differentiation potential. Therefore, induced pluripotent stem cells (iPSCs) have a great promise for this purpose due to their unique differentiation, self-renewal, and immunocompatibility. Current study was designed to determine therapeutic potential of human iPSCs (hiPSCs) in a mouse model of volumetric muscle loss. Muscles were subjected to excision to generate 30%-40% muscle loss. Next, hiPSCs were differentiated toward skeletal myogenic progenitors and used with fibrin hydrogel to reconstruct the lost muscle. Histologic evaluation of the treated muscles indicated abundant engraftment of donor-derived mature fibers expressing human markers. Donor-derived fibers were also positive for the presence of neuromuscular junction (NMJ), indicating their proper innervation. Evaluation of the engrafted region indicated the presence of donor-derived satellite cells expressing human markers and Pax7. Finally, in situ muscle function analysis demonstrated significant improvement of the muscle contractility in muscles treated with hiPSCs. These results therefore provide key evidence for the therapeutic potential of human iPSCs in volumetric muscle loss injuries.

Transplantation of insulin-like growth factor-1 laden scaffolds combined with exercise promotes neuroregeneration and angiogenesis in a preclinical muscle injury model

The regeneration of skeletal muscle can be permanently impaired by traumatic injuries, despite the high regenerative capacity of native muscle. An attractive therapeutic approach for treating severe muscle inuries is the implantation of off-the-shelf engineered biomimetic scaffolds into the site of tissue damage to enhance muscle regeneration. Anisotropic nanofibrillar scaffolds provide spatial patterning cues to create organized myofibers, and growth factors such as insulin-like growth factor-1 (IGF-1) are potent inducers of both muscle regeneration as well as angiogenesis. The aim of this study was to test the therapeutic efficacy of anisotropic IGF-1-releasing collagen scaffolds combined with voluntary exercise for the treatment of acute volumetric muscle loss, with a focus on histomorphological effects. To enhance the angiogenic and regenerative potential of injured murine skeletal muscle, IGF-1-laden nanofibrillar scaffolds with aligned topography were fabricated using a shear-mediated extrusion approach, followed by growth factor adsorption. Individual scaffolds released a cumulative total of 1244 ng ± 153 ng of IGF-1 over the course of 21 days in vitro. To test the bioactivity of IGF-1-releasing scaffolds, the myotube formation capacity of murine myoblasts was quantified. On IGF-1-releasing scaffolds seeded with myoblasts, the resulting myotubes formed were 1.5-fold longer in length and contained 2-fold greater nuclei per myotube, when compared to scaffolds without IGF-1. When implanted into the ablated murine tibialis anterior muscle, the IGF-1-laden scaffolds, in conjunction with voluntary wheel running, significantly increased the density of perfused microvessels by greater than 3-fold, in comparison to treatment with scaffolds without IGF-1. Enhanced myogenesis was also observed in animals treated with the IGF-1-laden scaffolds combined with exercise, compared to control scaffolds transplanted into mice that did not receive exercise. Furthermore, the abundance of mature neuromuscular junctions was greater by approximately 2-fold in muscles treated with IGF-1-laden scaffolds, when paired with exercise, in comparison to the same treatment without exercise. These findings demonstrate that voluntary exercise improves the regenerative effect of growth factor-laden scaffolds by augmenting neurovascular regeneration, and have important translational implications in the design of off-the-shelf therapeutics for the treatment of traumatic muscle injury.

Verifying the Versatility and Reliability of Free Lateral Arm Flap for Head and Neck Reconstruction

The lateral arm flap is an alternative to the conventional radial forearm flap and has been widely used due to advancements in flap characteristics. Especially, the fasciocutaneous flap has been widely used in head and neck reconstruction due to its versatile characteristics and surgical feasibility. This flap has successfully undergone several useful modifications based on various anatomical studies. Here, the authors aimed to verify the versatility and reliability of free lateral arm flap reconstruction of numerous head and neck defects. Twelve patients (6 men and 6 women; mean age, 66 years) with various types of lateral arm flaps from May 2017 to April 2019 were included. The anatomical reconstruction area was widely distributed across the facial subunits, tongue and oral cavity, and hypopharynx, among others. The flap varied in size from 3 × 5 cm to 17 × 7 cm, and the average pedicle length was 5.58 cm. The versatility of the lateral arm flap enabled successful coverage of various defects in all cases. Among 12 patients, the donor site outcome was rated as excellent and good by 2 and 10 patients, respectively. Three patients complained of post-operative hypoesthesia, which was subsequently resolved. The lateral arm flap is a unique and extremely versatile soft tissue free flap. Its versatility facilitates continuous modification of the flap and its application in various areas in different forms with excellent contour outcomes. The authors successfully verified the evolving methods and advantages of lateral arm flaps in the treatment of various head and neck defects.

The esthetic outcome of lower limb reconstruction

BACKGROUND

In recent years, the progress of anatomical knowledge and microsurgical techniques, in particular the development of perforator flaps, has risen the number of flaps available for lower leg reconstruction. The esthetic consequences of flap choice and harvest do have an impact on patients' quality of life. Nowadays, more researchers evaluate the esthetic changes following lower limb reconstruction.

OBJECTIVES

This review aims to summarize the available evidence on the esthetic outcome of lower limb reconstruction.

DATA SOURCES

A systematic review was planned to identify the most relevant indexed articles on this subject. The search was performed on Pubmed database without date of publication limits.

STUDY ELIGIBILITY CRITERIA

All papers about reporting information about the esthetic outcome of lower limb reconstruction were selected. Case reports and the articles not including specific information about complications, secondary procedures, and outcomes were excluded. The articles were categorized according to their topic and date of publication. The full texts of all the articles were obtained and read thoroughly. The references for each article were screened to identify articles that were eventually left outside our database search.

PARTICIPANTS, AND INTERVENTIONS

One hundred and eight articles were retained for the definitive review. Eleven review articles were kept because they represented a good source of information. Thirty-three articles were added after reading the full texts. The articles appear highly heterogeneous and at, this stage, only a critical and qualitative analysis could be performed.

RESULTS

We found information about 7895 lower reconstructions, 1295 local flaps, 6546 free flaps.

LIMITATIONS

The esthetic evaluation is intrinsic subjective. Many psychological and cultural factors influence both the patient and the surgeon. There is not a validated assessment tool for the esthetic outcome of lower leg reconstruction. Therefore, no quantitative analysis was performed.

CONCLUSIONS

Some ancient techniques are today obsolete, like the rectus abdominis free muscle flaps and perhaps free forearm flap, others are always useful, like gracilis and latissimus dorsi free flap. ALT flap is the most versatile perforator flap today available, but the SCIP flap is gaining the favor of a growing number of surgeons. Local flaps will be always performed with success but their indications should not be pushed beyond the medium-size defects. The best cosmetic outcome for each patient cannot necessarily be obtained neither with the easiest techniques nor with the most technically demanding ones. It is necessary to develop validated tools to assess the cosmetic outcome of lower limb reconstruction.

Elastin-Like Recombinamer Hydrogels for Improved Skeletal Muscle Healing Through Modulation of Macrophage Polarization

Large skeletal muscle injuries, such as a volumetric muscle loss (VML), often result in an incomplete regeneration due to the formation of a non-contractile fibrotic scar tissue. This is, in part, due to the outbreak of an inflammatory response, which is not resolved over time, meaning that type-1 macrophages (M1, pro-inflammatory) involved in the initial stages of the process are not replaced by pro-regenerative type-2 macrophages (M2). Therefore, biomaterials that promote the shift from M1 to M2 are needed to achieve optimal regeneration in VML injuries. In this work, we used elastin-like recombinamers (ELRs) as biomaterials for the formation of non- (physical) and covalently (chemical) crosslinked bioactive and biodegradable hydrogels to fill the VML created in the tibialis anterior (TA) muscles of rats. These hydrogels promoted a higher infiltration of M2 within the site of injury in comparison to the non-treated control after 2 weeks (p<0.0001), indicating that the inflammatory response resolves faster in the presence of both types of ELR-based hydrogels. Moreover, there were not significant differences in the amount of collagen deposition between the samples treated with the chemical ELR hydrogel at 2 and 5 weeks, and this same result was found upon comparison of these samples with healthy tissue after 5 weeks, which implies that this treatment prevents fibrosis. The macrophage modulation also translated into the formation of myofibers that were morphologically more similar to those present in healthy muscle. Altogether, these results highlight that ELR hydrogels provide a friendly niche for infiltrating cells that biodegrades over time, leaving space to new muscle tissue. In addition, they orchestrate the shift of macrophage population toward M2, which resulted in the prevention of fibrosis in the case of the chemical hydrogel treatment and in a more healthy-like myofiber phenotype for both types of hydrogels. Further studies should focus in the assessment of the regeneration of skeletal muscle in larger animal models, where a more critical defect can be created and additional methods can be used to evaluate the functional recovery of skeletal muscle.

Selecting a free flap for soft tissue coverage in lower extremity reconstruction

BACKGROUND

Goals of lower extremity microvascular reconstruction (LEMR) include the restoration of function, prevention of infection, and optimal cosmesis. Indications for LEMR include large defects that are not amenable to pedicled options, a large zone of injury, and large complex defects. The novice microsurgeon should first master a handful of free flaps to develop an armamentarium of options for addressing such defects. The scope of this review is to provide free flap options for LEMR in any of the thirds of the lower leg. After reading this article, the reader will understand variations, advantages, disadvantages, indications, and tips for raising each of these flaps.

METHODS

Six most commonly used free flaps for LEMR are described in this paper, including the anterolateral thigh flap (ALT) and its variations, the radial forearm flap (RFFF), the lateral arm flap (LAF), the gracilis muscle flap, the rectus abdominis flap (RAF) and the latissimus dorsi flap and its variations. Indications, advantages, disadvantages and technique tips are discussed for each flap. Moreover, selection of the recipient vessels, preoperative management along with an algorithm are also provided.

CONCLUSIONS

The ALT flap is a workhorse in covering defects of the leg, foot, and ankle. It's the flap of choice at our institution, especially given the number of traumatic wounds seen as a result of motor vehicles, all-terrain vehicles (ATV), lawnmowers, and gunshot wounds (GSW). At times, the lower extremity zone of injury requires a distant donor site. The RAF can also provide coverage for large soft tissue defects but donor-site morbidity remains its main drawback. The LAF and RFFF provide two pliable options, one that provides pliable soft tissue with minimal donor site morbidity and another that provides a long pedicle. The free gracilis flap is an excellent choice for crossing the ankle joint. Lastly, the free latissimus dorsi is indicated for large defects of the lower extremity independently of the location.

A Standard Algorithm for Reconstruction of Scalp Defects With Simultaneous Free Flaps in an Interdisciplinary Two-Team Approach

Reconstructions of complex scalp after ablative resection or by post-traumatic tissue loss, can present difficulties regarding recipient vessel selection, functional, and aesthetic outcome. The harvesting method for many microvascular free flaps requires a need for changing patients position during surgery and makes a simultaneous interdisciplinary two-team approach complicated, which is a major disadvantage regarding safety and operation time. The ideal flap for scalp reconstruction has yet to be described, although the microvascular latissimus dorsi flap is frequently referred to as the first choice in this context, especially after resection of large defects. The purpose of this study is to compare two different microvascular free flaps for a simultaneous scalp reconstruction in an interdisciplinary two-team approach applying a standardized algorithm. All consecutively operated complex scalp defects after ablative surgery from April 2017 until August 2018 were included in this retrospective study. The indications were divided into neoplasm or wound healing disorder. Two microvascular flaps (latissimus dorsi or parascapular flap) were used to cover the soft tissue component of the resulting defects. Seventeen patients met the inclusion criterion and were treated in an interdisciplinary two-team approach. Skull reconstruction with a CAD/CAM implant was performed in 10 cases of which four were in a secondary stage. Nine patients received a parascapular flap and eight patients were treated with latissimus dorsi flap with split thickness skin graft. Anastomosis was performed with no exception to the temporal vessels. One parascapular flap had venous insufficiency after 1 week followed by flap loss. One latissimus dorsi flap had necrosis of the serratus part of the flap. All other flaps healed uneventful and could be further treated with adjuvant therapy or CAD/CAM calvarial implants. Regarding overall complications, flap related complications, flap loss, and inpatient stay no statistical differences were seen between the diagnosis or type of reconstruction. The parascapular flap seems to be a good alternative for reconstruction of complex tumor defects of the scalp besides the latissimus dorsi flap. Stable long-term results and little donor site morbidity are enabled with good aesthetic outcomes and shorter operation time in an interdisciplinary two-team approach.

Conductive biomaterials for muscle tissue engineering

Muscle tissues are soft tissues that are of great importance in force generation, body movements, postural support and internal organ function. Muscle tissue injuries would not only result in the physical and psychological pain and disability to the patient, but also become a severe social problem due to the heavy financial burden they laid on the governments. Current treatments for muscle tissue injuries all have their own severe limitations and muscle tissue engineering has been proposed as a promising therapeutic strategy to treat with this problem. Conductive biomaterials are good candidates as scaffolds in muscle tissue engineering due to their proper conductivity and their promotion on muscle tissue formation. However, a review of conductive biomaterials function in muscle tissue engineering, including the skeletal muscle tissue, cardiac muscle tissue and smooth muscle tissue regeneration is still lacking. Here we reviewed the recent progress of conductive biomaterials for muscle regeneration. The recent synthesis and fabrication methods of conductive scaffolds containing conductive polymers (mainly polyaniline, polypyrrole and poly(3,4-ethylenedioxythiophene), carbon-based nanomaterials (mainly graphene and carbon nanotube), and metal-based biomaterials were systematically discussed, and their application in a variety of forms (such as hydrogels, films, nanofibers, and porous scaffolds) for different kinds of muscle tissues formation (skeletal muscle, cardiac muscle and smooth muscle) were summarized. Furthermore, the mechanism of how the conductive biomaterials affect the muscle tissue formation was discussed and the future development directions were included.

Secondary Reconstruction of Calvarial Defects by Using Free Flap: Report of Consecutive Cases and Analysis of Strategy

INTRODUCTION

Multiplication of incisions and/or radiotherapy on the scalp, lead to skin necrosis and chronic osteitis. In this situation, reconstructive surgery can be useful to cover complex lack of tissue.

MATERIALS AND METHODS

The 5 patients were treated with the neurosurgery department of our hospital. The procedure included debridement of the infected calvarian bone and tissues and coverage by free antebrachial flap. A 2 stages skin graft, using a dermal regeneration template, or direct closure was used for the donor site. Evaluation of flap quality and donor site morbidity was done during hospitalization and 3 months after the procedure.

RESULTS

The procedure was achieved on 5 patients. All the patients were healed 3 months after surgery. For 1 patient, a second procedure was done in emergency for anastomosis revision. There was non-complication concerning the donor site. All the patients healed with a good coverage.

CONCLUSION

Treatment of calvarian bone necrosis needs a very good and reliable coverage, such as free flap can provide. In our opinion, the antebrachial free flap is an interesting option, despite the fact that it is still underused for scalp coverage.

Treatment of volumetric muscle loss in mice using nanofibrillar scaffolds enhances vascular organization and integration

Traumatic skeletal muscle injuries cause irreversible tissue damage and impaired revascularization. Engineered muscle is promising for enhancing tissue revascularization and regeneration in injured muscle. Here we fabricated engineered skeletal muscle composed of myotubes interspersed with vascular endothelial cells using spatially patterned scaffolds that induce aligned cellular organization, and then assessed their therapeutic benefit for treatment of murine volumetric muscle loss. Murine skeletal myoblasts co-cultured with endothelial cells in aligned nanofibrillar scaffolds form endothelialized and aligned muscle with longer myotubes, more synchronized contractility, and more abundant secretion of angiogenic cytokines, compared to endothelialized engineered muscle formed from randomly-oriented scaffolds. Treatment of traumatically injured muscle with endothelialized and aligned skeletal muscle promotes the formation of highly organized myofibers and microvasculature, along with greater vascular perfusion, compared to treatment of muscle derived from randomly-oriented scaffolds. This work demonstrates the potential of endothelialized and aligned engineered skeletal muscle to promote vascular regeneration following transplantation.

Free Tissue Transfer for Upper Extremity Reconstruction

With the advent of the Industrial Revolution, traumatic injuries of the upper extremity increased exponentially. As a result, surgeons began to reevaluate amputation as the standard of care. Following the Second World War, local and regional pedicled flaps became common forms of traumatic upper extremity reconstruction. Today, microsurgery offers an alternative when options lower on the reconstructive ladder have been exhausted or will not produce a desirable result. In this article, the authors review the use of free tissue transfer for upper extremity reconstruction. Flaps are categorized as fasciocutaneous, muscle, and functional tissue transfers. The thin pliable nature of fasciocutaneous flaps makes them ideal for aesthetically sensitive areas, such as the hand. The radial forearm, lateral arm, scapula, parascapular, anterolateral thigh, and temporoparietal fascia flaps are highlighted in this article. Muscle flaps are utilized for their bulk and size; the latissimus dorsi flap serves as a "workhorse" free muscle flap for upper extremity reconstruction. Other muscle flaps include the rectus abdominis and serratus anterior. Lastly, functional tissue transfers are used to restore active range of motion or bony integrity to the upper extremity. The innervated gracilis can be utilized in the forearm to restore finger flexion or extension. Transfer of vascularized bone such as the fibula may be used to correct large defects of the radius or ulna. Finally, replacement of "like with like" is embodied in toe-to-thumb transfers for reconstruction of digital amputations.

Exclusive tongue tip reconstruction of hemiglossectomy defects using the underrated lateral arm free flap with bilobed design

Background

Tongue reconstruction is challenging with the unique function and anatomy. Goals for reconstruction differ depending on the extent of reconstruction. Thin and pliable flaps are useful for tongue tip reconstruction, for appearance and mobility. This study reports lateral arm free flap (LAFF) as a safe and optimal option for hemi-tongue reconstruction, especially for tongue tip after hemiglossectomy.

Methods

Thirteen LAFFs were performed for hemi-tongue reconstruction after hemiglossectomy from 1995 to 2018. Of the 13 patients, seven were male and six were female, age varying from 24 to 64 years.

Results

All flaps healed uneventfully without complications. Donor sites were closed primarily. The recipient vessels for microvascular anastomosis were mainly superior thyroidal artery, external jugular vein. All patients returned to normal diet, with no complaints regarding reconstructed tongue and donor site.

Conclusion

The LAFF is hairless, thin (especially with lateral epicondyle approach), and potentially sensate. They are advantageous features for tongue tip and hemi-tongue reconstruction. Donor site sacrifices the inessential posterior radial collateral artery, and the scar is hidden under short sleeve shirts. We believe that LAFF can be considered as the first choice flap for hemitongue reconstruction, over radial forearm free flaps.

One-stage reconstruction of complex soft tissue defects in the hands using multidigit, chimeric, lateral arm, perforator flaps

PURPOSE

To describe our experience using microsurgically fabricated, multilobed, chimeric, lateral arm (LA) flaps to reconstruct hand injuries with complex, multidigit, soft tissue defects and to evaluate the morbidity and esthetic and functional outcomes of the donor sites.

METHODS

We performed a single center, retrospective analysis of 21 patients with hand wounds treated from October 2013 to February 2016. All patients underwent reconstruction using multilobed, chimeric, free, LA flaps. A self-reported questionnaire was used to assess donor site morbidity and satisfaction with the esthetic and overall functional result. Outcome measures were the Disabilities of the Arm, Shoulder and Hand (DASH) score, static 2-point discrimination score, and visual analogue scale.

RESULTS

The study included 21 patients (20 males and 1 female), with an average age of 32.14 years (range 18-45 years), who sustained traumatic injuries in road traffic accidents (n = 2) or industrial devices (n = 19). The average DASH score was 28.25 ± 2.3, the average 2-PD score was 7.20 ± 1.30, and the average visual analogue scale (VAS) was 0.38 ± 0.40. All 21 patients had sensory disorders at the donor site. Postoperative donor site complications comprised wound dehiscence (n = 1) and hematoma (n = 3). The patient-rated satisfaction score for the donor site was 5.40 ± 0.90, and 70% of the patients would undergo the same surgery again.

CONCLUSION

Microsurgical fabrication of multilobed, chimeric, LA flaps can exhibit sensory recovery and minimal pain but may cause hematoma and sensory disorders at the donor site. The flaps are a viable alternative for the reconstruction of complex, multidigit, soft tissue defects of the hands.

Rehabilitative exercise and spatially patterned nanofibrillar scaffolds enhance vascularization and innervation following volumetric muscle loss

Muscle regeneration can be permanently impaired by traumatic injuries, despite the high regenerative capacity of skeletal muscle. Implantation of engineered biomimetic scaffolds to the site of muscle ablation may serve as an attractive off-the-shelf therapeutic approach. The objective of the study was to histologically assess the therapeutic benefit of a three-dimensional spatially patterned collagen scaffold, in conjunction with rehabilitative exercise, for treatment of volumetric muscle loss. To mimic the physiologic organization of skeletal muscle, which is generally composed of myofibers aligned in parallel, three-dimensional parallel-aligned nanofibrillar collagen scaffolds were fabricated. When implanted into the ablated murine tibialis anterior muscle, the aligned nanofibrillar scaffolds, in conjunction with voluntary caged wheel exercise, significantly improved the density of perfused microvessels, in comparison to treatments of the randomly oriented nanofibrillar scaffold, decellularized scaffold, or in the untreated control group. The abundance of neuromuscular junctions was 19-fold higher when treated with aligned nanofibrillar scaffolds in conjunction with exercise, in comparison to treatment of aligned scaffold without exercise. Although, the density of de novo myofibers was not significantly improved by aligned scaffolds, regardless of exercise activity, the cross-sectional area of regenerating myofibers was increased by > 60% when treated with either aligned and randomly oriented scaffolds, in comparison to treatment of decellularized scaffold or untreated controls. These findings demonstrate that voluntary exercise improved the regenerative effect of aligned scaffolds by augmenting neurovascularization, and have important implications in the design of engineered biomimetic scaffolds for treatment of traumatic muscle injury.

A collagen scaffold designed to mimic skeletal muscle, together with rehabilitative exercise, can help regenerate nerves and blood vessels following traumatic muscle injury. Ngan Huang from Stanford University, California, USA, and colleagues created scaffolding composed of collagen nanofibers aligned in parallel, as natural muscle fibers are. They implanted these specially patterned collagen constructs into the shins of mice that had no tibialis anterior muscles. Mice given the opportunity to exercise formed far more nerve connections in their injured muscles compared to mice without exercise wheels in their cages. Active mice also developed significantly more blood vessels in their injured muscles with the parallel-aligned scaffolds compared to other animals with randomly oriented scaffolds, decellularized scaffolds or no implant at all. The findings highlight the potential of combining exercise and biomimetic scaffolds to treat muscle trauma.

Current Methods for Skeletal Muscle Tissue Repair and Regeneration

Skeletal muscle has the capacity of regeneration after injury. However, for large volumes of muscle loss, this regeneration needs interventional support. Consequently, muscle injury provides an ongoing reconstructive and regenerative challenge in clinical work. To promote muscle repair and regeneration, different strategies have been developed within the last century and especially during the last few decades, including surgical techniques, physical therapy, biomaterials, and muscular tissue engineering as well as cell therapy. Still, there is a great need to develop new methods and materials, which promote skeletal muscle repair and functional regeneration. In this review, we give a comprehensive overview over the epidemiology of muscle tissue loss, highlight current strategies in clinical treatment, and discuss novel methods for muscle regeneration and challenges for their future clinical translation.

Minimizing free flap donor-site morbidity

PURPOSE OF REVIEW

Fasciocutaneous and osteocutaneous free flap reconstruction has significantly changed the way surgeons reconstruct defects following ablation of head and neck tumors. Over time, success rates of free flaps have approached 98%, allowing surgeons to shift their focus to minimizing morbidities associated with the donor sites. The radial forearm, anterolateral thigh, and fibula free flaps are the three most commonly used flaps in head and neck reconstruction, and therefore each of their advantages and associated morbidities are of particular interest. The present article aims to review the morbidities associated with each of the commonly used head and neck free flaps and techniques to minimize them that are described in the most recent literature.

RECENT FINDINGS

New techniques such as negative-pressure wound therapy, full thickness grafts, and rotational flaps have been developed recently that minimize these morbidities.

SUMMARY

The techniques described in the current review may improve long-term patient outcomes both esthetically and functionally.

Evaluation of donor site morbidity after medial triceps brachii free flap for lower limb reconstruction

INTRODUCTION

The medial head of the triceps brachii muscle (MTB)-free flap is an attractive solution to cover small-to-medium defects of the lower limb. This muscular head has no well-identified function, suggesting minimal impact of its removal on elbow mobility. The aim of this study was to evaluate the safety and reliability of the harvest procedure and the functional and cosmetic morbidity of this donor site.

MATERIALS AND METHODS

Twenty-four consecutive MTB-free flaps were performed for reconstructive surgery of the lower limb between 2011 and 2015. Patients and their records were retrospectively examined. Functional results were evaluated by assessing elbow extension strength using a dynamometer and with a QuickDASH questionnaire. Cosmetic results were assessed using the POSAS observer and patient scales.

RESULTS

Twenty-four patients were followed up postoperatively for an average of 33.9 [min 12-max 59] months. No major complication (in particular, no ulnar or radial nerve injury) occurred during harvest. No patient complained of elbow pain or reduction in strength. Elbow extension was complete in all patients and the mean strength was calculated at 89 [61.1-112.5] % of the opposite arm. The POSAS scale scored an average 8.6 [7-21] for the observer and 10 [7-26] for the patient. Cosmetic results using the POSAS scale were satisfactory in all patients.

CONCLUSIONS

Objective evaluation of patients who underwent an MTB-free flap for limb reconstruction shows no impact of the harvesting procedure on elbow extension. Patient satisfaction with the donor site was high. From this retrospective study, it appears that this surgery is safe, aesthetically acceptable, and has minimal impact on donor site elbow function.

Functional donor site morbidity longer than one year after fibula free flap: A prospective biomechanical analysis

OBJECTIVES

The fibula free flap is the workhorse procedure for osseous reconstruction. The objective of this study was to investigate long-term functional outcomes of the harvesting site.

PATIENTS AND METHODS

About 19 patients (10 male, 9 female, mean age 58.1 years) were available for the long-term analysis 13-51 months after surgery. Jumping mechanography and balance testing on a ground force reaction plate (Leonardo Mechanograph GFRP) were performed before and surgery. The Esslinger Fitness Index (EFI, maximum peak power in W/kg normalized for age and gender) was considered as primary endpoint. Secondary outcomes were maximum force, range of motion in the ankle joint, sensory limitations, the American Orthopedic Foot and Ankle Society Score (AOFAS-Score), and subjective perceptions.

RESULTS

We found no significant difference between pre- and postoperative EFI (70.4% versus 66.0%, P = 0.07) and body sway (1.72 cm² versus 2.60 cm² , P = 0.093). The AOFAS-Score was reduced by 8.8 points (99.1 points versus 90.3 points, P < 0.001). Dorsal extenstion (31.6° versus 24.1°, P < 0.001) and flexion (32.3 versus 25.6° flexion, P = 0.011) were significantly reduced and 6 patients had chronic pain.

CONCLUSIONS

Reduced peak power and balance ability seem to be reversible short-term effects after fibula harvesting. We recommend preoperative patient education and standardized protocols for physiotherapy.