A favorable donor site in microsurgery: Nerve and vein graft harvest from the dorsum of the foot.

BACKGROUND AND OBJECTIVES: In complex hand traumas nerves and vessels are often destructed without the possibility for primary repair. For bridging defects of nerves, veins and arteries grafts are necessary. Commonly nerve and vein grafts from adjacent donor sites as the wrist, forearm or cubital region are harvested. METHODS: This study is a retrospective cohort study. Between 2017 and 2019, 10 patients with complex hand injuries were treated. There were 8 males and 2 females, with an average age of 39 years (range 8-63 years). In all cases grafts were used of the dorsum of the foot for reconstructing of the severed digital nerves and arteries. All donor sites could be closed primarily. RESULTS: In 100% of cases nerves and veins of the dorsum of the foot showed a good size match as well as adequate length for a sufficient repair. The overall Hand Injury Severity Score (HISS) was determined with a median of 86 (range 57 to 286). In the area of the donor site no relevant complications were seen. CONCLUSIONS: In complex hand injuries the dorsum of the foot is a favorable donor site for nerve and vein graft harvest.

Author Correction: Rapid and Precise Semi-Automatic Axon Quantification in Human Peripheral Nerves.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Rapid and Precise Semi-Automatic Axon Quantification in Human Peripheral Nerves.

We developed a time-efficient semi-automated axon quantification method using freeware in human cranial nerve sections stained with paraphenylenediamine (PPD). It was used to analyze a total of 1238 facial and masseteric nerve biopsies. The technique was validated by comparing manual and semi-automated quantification of 129 (10.4%) randomly selected biopsies. The software-based method demonstrated a sensitivity of 94% and a specificity of 87%. Semi-automatic axon counting was significantly faster (p < 0.001) than manual counting. It took 1 hour and 47 minutes for all 129 biopsies (averaging 50 sec per biopsy, 0.04 seconds per axon). The counting process is automatic and does not need to be supervised. Manual counting took 21 hours and 6 minutes in total (average 9 minutes and 49 seconds per biopsy, 0.52 seconds per axon). Our method showed a linear correlation to the manual counts (R = 0.944 Spearman rho). Attempts have been made by several research groups to automate axonal load quantification. These methods often require specific hard- and software and are therefore only accessible to a few specialized laboratories. Our semi-automated axon quantification is precise, reliable and time-sparing using publicly available software and should be useful for an effective axon quantification in various human peripheral nerves.

WITHDRAWN: The use of integrated indocyanine green fluorescence microscope camera for intraoperative lymphography of supermicrosurgery.

Ahead of Print article withdrawn by publisher.

Perfusion maintains functional potential in denervated mimic muscles in early persistent facial paralysis which requires early microsurgical treatment - the histoanatomic basis of the extratemporal facial nerve trunk assessing axonal load in the context of possible nerve transfers.

BACKGROUND AND OBJECTIVES: Early persistent facial paralysis is characterized by intact muscles of facial expression through maintained perfusion but lacking nerve supply. In facial reanimation procedures aiming at restoration of facial tone and dynamics, neurotization through a donor nerve is performed. Critical for reanimating target muscles is axonal capacity of both donor and recipient nerves. In cases of complete paralysis, the proximal stump of the extratemporal facial nerve trunk may be selected as a recipient site for coaptation. To further clarify the histological basis of this facial reanimation procedure we conducted a human cadaver study examining macro and micro anatomical features of the facial nerve trunk including its axonal capacity in human cadavers. Axonal loads, morphology and morbidity of different donor nerves are discussed reviewing literature in context of nerve transfers. METHODS: From 6/2015 to 9/2016 in a group of 53 fresh frozen cadavers a total of 106 facial halves were dissected. Biopsies of the extratemporal facial nerve trunk (FN) were obtained at 1 cm distal to the stylomastoid foramen. After histological processing and digitalization of 99 specimens available, 97 were selected eligible for fascicle counts and 87 fulfilled quality criteria for a semi-automated computer-based axon quantification software using ImageJ/Fiji. RESULTS: An average of 3.82 fascicles (range, 1 to 9) were noted (n = 97). 6684±1884 axons (range, 2655- 12457) were counted for the entire group (n = 87). Right facial halves showed 6364±1904 axons (n = 43). Left facial halves demonstrated 6996±1833 axons (n = 44) with no significant difference (p = 0.73). Female cadavers featured 6247±2230 (n = 22), male showed 6769±1809 axons (n = 40). No statistical difference was seen between genders (p = 0.59). A comparison with different studies in literature is made. The nerve diameter in 82 of our specimens could be measured at 1933±424 µm (range, 975 to 3012). CONCLUSIONS: No donor nerve has been described to match axonal load or fascicle number of the extratemporal facial nerve main trunk. However, the masseteric nerve may be coapted for neurotization of facial muscles with a low complication rate and good clinical outcomes. Nerve transfer is indicated from 6 months after onset of facial paralysis if no recovery of facial nerve function is seen.

The nerve supply of zygomaticus major: Variability and distinguishing zygomatic from buccal facial nerve branches.

The zygomaticus major (ZM) is important for the human smile. There are conflicting data about whether the zygomatic or buccal branches of the facial nerve are responsible for its motor innervation. The literature provides no precise distinction of the transition zone between these two branch systems. In this study, a definition to distinguish the facial nerve branches at the level of the body of the zygoma is proposed. In the light of this definition, we conducted an anatomical study to determine how the source of innervation of the ZM was distributed. A total of 96 fresh-frozen cadaveric facial halves were dissected under loupe magnification. A hemiparotidectomy was followed by antegrade microsurgical dissection. Any branch topographically lying superficial to the zygoma or touching it was classed as zygomatic, and any neighboring inferior branch was considered buccal. The arborization of the facial nerve was diffuse in all cases. In 64 out of 96 specimens (67%, 95% CI: 56% to 76%), zygomatic branches innervated the ZM. Buccal branches innervated ZM in the other 32 facial halves (33%, 95% CI: 24% to 44%). There were no differences in respect of sex or facial side. All facial halves displayed additional branches, which crossed the muscle on its inner surface without supplying it. In 31 specimens, a nerve branch ran superficial to ZM in its cranial third. According to our classification, the zygomaticus major is innervated by zygomatic branches in 67% of cases and by buccal branches in 33%. Clin. Anat. 31:560-565, 2018. © 2018 Wiley Periodicals, Inc.

Transepidermal oxygen flux during arterial occlusion using ratiometric luminescence imaging.

BACKGROUND: A physiological oxygen transport through a circulatory and microcirculatory system is essential for execution of cellular functions. Several pathological conditions e.g. infections, ischemia, cancer, diabetes, hypertension or chronic wounds show a change of oxygen distribution and oxygen tension in cellular microenvironment. Additionally complex operative procedures in order to reconstruct tissue defects require a reliable monitoring of microcirculation. OBJECTIVE: Target of this study was to evaluate skin oxygenation during an ischemia-reperfusion experiment using transepidermal oxygen flux imaging. METHODS: Twelve patients at the Department of Plastic and Reconstructive surgery of the University hospital of Regensburg underwent to elective hand operations. During the operation a tourniquet is standardly set on the upper arm to create ischemia in order to facilitate the operative procedure. Measurements were performed at the different time intervals: in rest, under ischemia and after reperfusion. RESULTS: The transepidermal oxygen flux increased during the ischemic condition compared to normal condition and decreased to a lower value during reperfusion (rest: 0.043±0.007, ischemia: 0.063±0.014, reperfusion: 0.030±0.028). CONCULSION: Transepidermal oxygen flux imaging by ratiometric luminescence imaging seems to be a reliable tool to assess skin oxygenation. However dynamic changes seem to be more informative than absolute thresholds. Further investigations are necessary to prove these promising results.

Transepidermal oxygen flux measurement - First clinical application for postoperative wound monitoring.

BACKGROUND: Measurement of skin oxygen is of great interest in diverse fields of medicine. Different pathologies, e.g. infection, ischemia cancer or chronic wounds show a characteristic oxygen distribution and skin oxygen tension. Additionally diverse operative procedures require a reliable postoperative monitoring in order to ensure success of the therapy. OBJECTIVE: Aim of this study was to assess transepidermal oxygen flux for postoperative wound monitoring after operative treatment of fractures close to the hip. METHODS: 22 patients underwent transepidermal oxygen flux measurement at the first postoperative day. Transepidermal oxygen flux measurement was performed using ratiometric luminescence imaging. Examination was conducted in close proximity to the operation wound. The corresponding area at the contralateral side served as reference. RESULTS: Oxygen flux in the operation area was higher (0.084±0.021) than the contralateral side (0.071±0.029). CONCLUSIONS: Transepidermal oxygen flux imaging by ratiometric luminescence imaging seems to be a reliable tool to assess postoperative wound healing. However further investigations in greater populations and under pathologic conditions have to be performed to prove these first results.

Scalp reconstruction: A 10-year retrospective study.

Scalp reconstruction is a challenging task for the reconstructive surgeon. In consideration of the anatomical and cosmetic characteristics, the defect depth and size, an armamentarium of reconstructive procedures ranging from skin grafts over local flaps to free tissue transfer has been described. In this 10-year retrospective study, 85 operative procedures for scalp reconstruction were performed at our department. The underlying entity, defect size/depth, reconstructive procedure, complications, and mean hospital stay were analyzed. In most cases, scalp reconstruction was necessary after oncologic resection (67%) or radiation therapy (16%). A total of 85 operative procedures were performed for scalp reconstruction including local flaps (n = 50), free tissue transfer (n = 18), and skin grafts (n = 17). Regarding the complication rate, we could detect an overall major complication rate of 16.5% with one free flap loss. Briefly, local flaps are an adequate and safe procedure for limited scalp defects. In the case of extensive scalp defects affecting the calvarium, prior multiple surgical interventions and/or radiation, we prefer free tissue transfer.

Extracorporeal Free Flap Perfusion in Case of Prolonged Ischemia Time.

In free flap surgery, a clinically established concept still has to be found for the reduction of ischemia-related cell damage in the case of prolonged ischemia. Although promising results using extracorporeal free flap perfusion in the laboratory have been published in the past, until now this concept has not yet paved its way into clinical routine. This might be due to the complexity of perfusion systems and a lack of standardized tools. Here, we want to present the results of the first extracorporeal free flap perfusion in a clinical setting using a simple approach without the application of a complex perfusion machinery.

[Establishment and Evaluation of a Microsurgery Course for Medical Students]. / Etablierung und Evaluation eines Mikrochirurgie - Kurses für Medizinstudierende.

BACKGROUND: Very few microsurgical courses have been offered for medical students in Germany to date. To raise early interest in this technique, which is essential for plastic and reconstructive surgery, and to guide eligible medical students to choose plastic surgery as their specialist field, the Department of Plastic and Hand Surgery, supported by the Faculty of Medicine of the Friedrich-Alexander-University of Erlangen-Nuremberg, implemented a microsurgical course for students in 2011. This study describes the implementation of that course and evaluates its impact on the subsequent choice of the participants' specialist fields. MATERIAL AND METHODS: Since the summer of 2011, the microsurgery course for medical students has taken place regularly 3 times per term. It is free of charge for participants and is guided by senior physicians of the Department of Plastic and Hand Surgery together with student tutors from the Faculty of Medicine. The arterial end-to-end anastomosis in the fresh chicken leg is used as a training model. Based on a questionnaire survey the participants were evaluated and statistically analysed regarding their course satisfaction, self-assessment of their own eligibility before and after the course, the anticipated future choice of their medical specialist field and how their choice was influenced by this course. RESULTS: After the successful implementation of the microsurgical course in 2011, a significant number of students were interested in microsurgery. According to the questionnaire, the level of enthusiasm was high among all participants. The self-assessment of microsurgical skills improved significantly after the course compared with the pre-course assessment. In 82% of the participants, the course had a strong positive influence on the future choice of their specialist field. CONCLUSIONS: The regular implementation of a microsurgical course for students in the form described here is practicable and possible without undue personnel and cost of materials. The ongoing interest among students in such an offer is enormous and the satisfaction of the participants is very high. This might be a way to recruit future plastic surgeons by raising early enthusiasm for microsurgery. These future plastic surgeons, in turn, would be given the chance to experience a very fascinating aspect of plastic surgery, which might help them to decide on their specialisation within that field at a later point in their career.

Nutrient free flaps with vascular bypasses for extremity salvage in patients with chronic limb ischemia.

AIM: Treatment of severe wounds remains a surgical challenge in patients with critical limb ischemia (CLI). In some patients with end stage disease a combined arterial and venous vascular bypass together with immediate or subsequent free soft tissue transfer can become necessary to salvage the limb. The aim of this paper was to develop an algorithm of differential approaches of interdisciplinary reconstructions with bypasses and free flaps for leg salvage. METHODS: From our experiences with over 76 patients receiving a vascular bypass and a free microsurgical tissue transfer, we analyzed the various configurations of possible vascular constellations and treatment options. We derived an algorithm for the combined interdisciplinary surgical approach. RESULTS: We found the surgical technique to be one of the main predictors for the final outcome and categorized the various options and vascular configurations in combination with free flaps to salvage extremities. The overall complication rate with more than 20% revisional surgeries is higher than in routine free flap transfer for reconstructions in patient without CLI. We observed 3 failures (4%) with complete flap loss and bypass occlusion and found 3 patients (4%) with initially successful reconstructions to have secondary amputations within 6 to 18 months postoperatively. CONCLUSION: Given the multitude of concomitant diseases in patients with serious wounds and CLI the distinct choice of the individual reconstructive vascular/flap-procedure has to be thoroughly selected. Any treatment decision against revascularization must be made only with proper and adequate diagnosis based on proper and sufficient diagnostic imaging techniques following an interdisciplinary discussion of possible options for limb salvage. Based on our experience with a large series of this type of combined revascularization-flap reconstruction we developed a specific algorithm of surgical variants of bypass-free flap arterial and venous reconstructions that is presented in this paper.

[Osteomyelitis: treatment concepts from the plastic surgeon's point of view]. / Osteomyelitis : Behandlungskonzepte aus Sicht der plastischen Chirurgie.

Despite promising advances in antibiotic and surgical therapy osteomyelitis remians a severe disease with a high morbidity. Nowadays it occurs mainly after traumata. Typical clinical manifestations are signs of local infection, non-healing wounds, pathological fractures or loosening of orthopedic implants. Besides the clinical judgement the diagnosis is consolidated by imaging procedures, histopathological and microbiological examinations. Ideally, the treatment plan is based on an interdisciplinary approach. Besides the radical surgical debridement a test appropriate antibiotic therapy is essential. Defect reconstruction after surgical debridement and optimization of local microcirculation is essential to preserve limbs and to obtain a good functional result. Microsurgical free tissue transfer is often necessary to achieve healing. An optimal therapeutic management with stable long-term clinical results can be achieved by the interaction of different surgical and medical disciplines.

[Perforator flaps. A new era in reconstructive surgery]. / Perforatorlappen. Eine neue Ära in der rekonstruktiven Chirurgie.

Multimodal therapeutic concepts in cancer therapy more and more often allow a curative approach even in advanced stages of the disease. Frequently, however, the radical resection of tumor tissue results in a significant defect of the soft tissue and the reconstruction is a challenge for reconstructive surgery. As tissue engineering for artificial tissue replacement predominantly still remains experimental, reconstruction of defects with autologous tissue constitutes state of the art treatment. Different types of flaps are used, which are, however, are accompanied by sometimes substantial defects at the donor site. To reduce donor site morbidity so-called perforator flaps represent an interesting option in modern reconstructive surgery. The flaps are raised without the underlying muscle which means a reduction of donor site morbidity to a minimum. As there still remains a residual risk for failure precise preoperative planning should be given a high priority. The use of modern imaging procedures, such as computed tomography (CT) angiography, can minimize the risk of total loss of the flap, making the use of perforator flaps a safe procedure in modern reconstructive surgery.