Oral rehabilitation and associated quality of life following mandibular reconstruction with free fibula flap: a cross-sectional study

Introduction

Mandibular reconstruction with the free fibula flap (FFF) has become a standardized procedure. The situation is different with oral rehabilitation, so the purpose of this study was to investigate the frequency of implant placement and prosthetic restoration. Additionally, the patients' situation, motivation, and treatment course were structurally assessed.

Materials and methods

All cases between January 2013 and December 2018 that underwent mandibular reconstruction in our department with a free fibula flap and gave written informed consent to participate were interviewed with two structured questionnaires about their restoration and quality of life. Additionally, medical records, general information, status of implants and therapy, and metric analyses of the inserted implants were performed.

Results

In total 59 patients were enrolled and analyzed in this monocentric study. Overall, oral rehabilitation was achieved in 23.7% at the time of investigation. In detail, implants were inserted in 37.3% of patients and showed an 83.3% survival of dental implants. Of these implanted patients, dental implants were successfully restored with a prosthetic restoration in 63.6. Within this subgroup, satisfaction with the postoperative aesthetic and functional result was 79.9% and with the oral rehabilitation process was 68.2%. Satisfaction with the implant-borne prosthesis was 87.5%, with non-oral-squamous-cell-carcinoma patients being statistically significantly more content with the handling (p=0.046) and care (p=0.031) of the prosthesis.

Discussion

Despite the well-reconstructed bony structures, there is a need to increase the effort of achieving oral rehabilitation, especially looking at the patient's persistent motivation for the procedure.

Comparison of three-dimensional imaging of the nose using three different 3D-photography systems: an observational study

BACKGROUND

New 3D technologies for superficial soft tissue changes, especially in plastic and reconstructive surgical procedures, can improve the planning and documentation of facial surgeries. The purpose of this study was to compare and determine the applicability and feasibility of three different 3D-photography systems in clinical practice imaging the nose.

METHODS

A total of 16 healthy non-operated noses were included in this prospective study. A plaster model of each nose was produced, digitized, and converted to a .stl mesh (= ground truth model). Three-dimensional images of each nose were then taken using Artec Space Spider (gold standard), Planmeca ProFace®, and the Bellus3D Dental Pro application. All resulting .stl files were aligned to the ground truth model using MeshLab software, and the root mean square error (RMSE), mean surface distance (MSD), and Hausdorff distance (HD) were calculated.

RESULTS

The Artec Space Spider 3D-photography system showed significantly better results compared to the two other systems in regard to RMSE, MSD, and HD (each p < 0.001). There was no significant difference between Planmeca ProFace® and Bellus3D Dental Pro in terms of RMSE, MSD, and HD. Overall, all three camera systems showed a clinically acceptable deviation to the reference model (range: -1.23-1.57 mm).

CONCLUSIONS

The three evaluated 3D-photography systems were suitable for nose imaging in the clinical routine. While Artec Space Spider showed the highest accuracy, the Bellus3D Dental Pro app may be the most feasible option for everyday clinical use due to its portability, ease of use, and low cost. This study presents three different systems, allowing readers to extrapolate to other systems when planning to introduce 3D photography in the clinical routine.

Perioperative anticoagulation in head and neck free flap reconstructions: Experience of an anticoagulative scheme and its modification

OBJECTIVES

Microvascular anastomoses in microvascular reconstructions induce rheological changes in the anastomosed vessels and are usually counteracted by anticoagulative medication. There is no regimen commonly agreed on. This study provides an easy to use anticoagulative regimen.

PATIENTS AND METHODS

Consecutive cases of either anticoagulative regimen between 2013 and 2018 that underwent microvascular reconstruction in the head and neck area were included in this retrospective study, resulting in 400 cases in total. Two different anticoagulative regimens were applied to 200 patients in each group: (a) intraoperatively administered unfractionated 5000 I.U. high molecular weight heparin (HMWH) and postoperatively low molecular weight heparin (LMWH, Enoxaparin) 1 mg/kg/body weight postoperatively and (b) intraoperatively LMWH 0.5 mg/kg/body weight as well as 12 h later and 1 mg/kg/body weight postoperatively.

RESULTS

The LMWH cohort showed fewer overall thromboembolic (8.5% vs. 11%; p = .40) and peripheral thrombotic events (1% vs. 3.5%; p = .18) and lung embolisms (3% vs. 4%; p = .59). The number of thromboses at the site of the anastomosis was equally distributed. In regard to flap-specific complications, LMWH was associated with a positive effect, in particular with respect to total flap losses (5% vs. 7%; p = .40) and wound-healing disorders (14.5% vs. 20%; p = .145).

CONCLUSION

Findings indicate that intra- and postoperatively administered LMWH as the only anticoagulative medication seems reliable in our clinical routine of head and neck free flap reconstructions.

Face the Future-Artificial Intelligence in Oral and Maxillofacial Surgery

Artificial intelligence (AI) has emerged as a versatile health-technology tool revolutionizing medical services through the implementation of predictive, preventative, individualized, and participatory approaches. AI encompasses different computational concepts such as machine learning, deep learning techniques, and neural networks. AI also presents a broad platform for improving preoperative planning, intraoperative workflow, and postoperative patient outcomes in the field of oral and maxillofacial surgery (OMFS). The purpose of this review is to present a comprehensive summary of the existing scientific knowledge. The authors thoroughly reviewed English-language PubMed/MEDLINE and Embase papers from their establishment to 1 December 2022. The search terms were (1) "OMFS" OR "oral and maxillofacial" OR "oral and maxillofacial surgery" OR "oral surgery" AND (2) "AI" OR "artificial intelligence". The search format was tailored to each database's syntax. To find pertinent material, each retrieved article and systematic review's reference list was thoroughly examined. According to the literature, AI is already being used in certain areas of OMFS, such as radiographic image quality improvement, diagnosis of cysts and tumors, and localization of cephalometric landmarks. Through additional research, it may be possible to provide practitioners in numerous disciplines with additional assistance to enhance preoperative planning, intraoperative screening, and postoperative monitoring. Overall, AI carries promising potential to advance the field of OMFS and generate novel solution possibilities for persisting clinical challenges. Herein, this review provides a comprehensive summary of AI in OMFS and sheds light on future research efforts. Further, the advanced analysis of complex medical imaging data can support surgeons in preoperative assessments, virtual surgical simulations, and individualized treatment strategies. AI also assists surgeons during intraoperative decision-making by offering immediate feedback and guidance to enhance surgical accuracy and reduce complication rates, for instance by predicting the risk of bleeding.

Effect of segmental versus marginal mandibular resection on local and lymph node recurrences in oral squamous cell carcinoma: is tumorous bone infiltration or location and resulting soft tissue recurrences a long-term problem?

PURPOSE

Oral squamous cell carcinomas (OSCCs) adjacent to the mandible or with clinically suspected bone infiltration are surgically treated either with marginal or segmental resections. This retrospective study compared both resections regarding local recurrence and lymph node recurrence or secondary lymph node metastases.

METHODS

All consecutive primary OSCC cases between January 2007 and December 2015 that underwent mandibular marginal or segmental resection were included. Rates of local and lymph node recurrences or secondary metastases and possible risk factors such as tumor localization according to Urken's classification were recorded.

RESULTS

In total, 180 patients with 85 marginal (group I) and 95 segmental (group II) mandibular resections were analyzed. The local recurrence rates were comparable between the groups (28.2% vs. 27.4%; p = 0.897). Lymph node recurrences or secondary metastases were higher in group I (9.4% (n = 8) vs. 6.2% (n = 6); p = 0.001). Tumor localization appears to affect the outcomes. Significantly fewer local and lymph node recurrences/metastases were found for Urken's classification SB and S calculated by two-proportion z-test (p = 0.014 and 0.056, respectively). Local recurrences mostly emerged from soft tissues, which should be resected more radically than the bones.

CONCLUSION

While bone infiltration appears technically well controllable from an oncologic point of view, local recurrences and lymph node recurrences/metastases remain an issue. Regular clinical aftercare with imaging is crucial to detect recurrences.

The COVID-19 pandemic and its possible impact on the treatment of odontogenic and intraoral abscesses

Most odontogenic and intraoral abscesses can be treated on an outpatient basis with local anesthesia. However, severe disease progression may require an incision under general anesthesia (GA) with postoperative inpatient treatment. This study aimed to evaluate the first "COVID-19 year" in Germany and compare the first "COVID-19 year" with the two previous years. All consecutive cases with odontogenic or intraoral abscesses treated in an outpatient or inpatient setting between 2018 and 2021 were included in this study. Data were collected, including the type of anesthesia, length of hospital stay, and healthcare costs. Despite the lower total number of abscess treatments in the first year of COVID-19 (n = 298 patients) than that in the two previous years (n = 663 patients), the number of advanced abscesses requiring intervention under GA was significantly higher (p < 0.001). This increased burden of care was also reflected in increased healthcare costs. The measures taken against the COVID-19 pandemic had an impact on the course of other diseases, for example, odontogenic and intraoral abscesses. The results showed an emerging conflict in patient care during the pandemic crisis that should be considered in possible future pandemics.

Comparison of a high-definition three-dimensional digital camera system with a conventional state-of-the-art operation microscope for microsurgical anastomoses

Since its clinical implementation, microvascular surgery has depended on the continuous improvement of magnification tools. One of the more recent developments is a high-definition three-dimensional (3D) digital system (exoscope), which provides an alternative to the state-of-the-art operating microscopes. This study aimed to evaluate the advantages and disadvantages of this technology and compare it with its predecessor. The study included 14 surgeons with varying levels of experience, none of which had used a 3D optical system previously. Six of these surgeons performed five arterial and five venous anastomoses in the chicken thigh model with both the VITOM 3D exoscope-guided system and the Pentero operating microscope. These anastomoses were then evaluated for their quality and anastomosis time. The participants and the other eight surgeons, who had used the digital 3D camera system for microsurgical training exercises and vascular sutures, answered a questionnaire. The anastomosis time and number of complications were lower with the conventional microscope. Participants rated the image quality with the conventional microscope as higher, whereas the field of view and ergonomics were favorable in the digital 3D camera system. Exoscopes are optics suitable for performing simple microvascular procedures and are superior to classical microscopes ergonomically. Thus far, they are inferior to classical microscopes in terms of image quality and 3D imaging.

Infantile human labial glands: Distribution of aquaporins and claudins in the context of paracellular and transcellular pathways

Human labial glands consist of saliva-secreting cells which are formed by serous and predominantly mucous glandular cells. The following excretory duct system converts the isotonic saliva into a hypotonic fluid. Liquids are transported across the membrane of epithelial cells by paracellular or transcellular mode of action. We studied aquaporins (AQP) and tight junction proteins in the endpieces and duct system of human labial glands of 3-5-month-old infants for the first time. AQP1, AQP3, and AQP5 represent the transcellular transport; tight junction proteins like claudin-1, - 3, - 4, and - 7 regulate the permeability of the paracellular pathway. Specimens of 28 infants were included in this study and analyzed histologically. AQP1 was present in myoepithelial cells and in endothelial cells of small blood vessels. AQP3 showed basolateral plasmamembrane localization in glandular endpieces. AQP5 was localized at the apical cytomembrane in serous and mucous glandular cells and at the lateral membrane in serous cells. Ducts remained unstained with the antibody to AQP1, AQP3, and AQP5. Claudin-1, - 3, - 4, and - 7 were expressed mainly in the lateral plasmamembrane of serous glandular cells. In the ducts, claudin-1, - 4, and - 7 were detected at the basal cell layer, claudin-7 also at the lateral cytomembrane. Our findings provide new insights into the localization of epithelial barrier components necessary for regulating saliva-modification in infantile labial glands.

Imaging of traumatic mandibular fractures in young adults using CT-like MRI: a feasibility study

OBJECTIVES

To assess and compare the diagnostic performance of CT-like images based on a three- dimensional (3D) T1-weighted spoiled gradient-echo sequence (3D T1 GRE) with CT in patients with acute traumatic fractures of the mandible.

MATERIALS AND METHODS

Subjects with acute mandibular fractures diagnosed on conventional CT were prospectively recruited and received an additional 3 T MRI with a CT-like 3D T1 GRE sequence. The images were assessed by two radiologists with regard to fracture localization, degree of dislocation, and number of fragments. Bone to soft tissue contrast, diagnostic confidence, artifacts, and overall image quality were rated using a five-point Likert-scale. Agreement of measurements was assessed using an independent t-test.

RESULTS

Fourteen subjects and 22 fracture sites were included (26 ± 3.9 years; 4 females, 10 males). All traumatic fractures were accurately detected on CT-like MRI (n = 22, κ 1.00 (95% CI 1.00-1.00)). There was no statistically significant difference in the assessment of the fracture dislocation (axial mean difference (MD) 0.06 mm, p = 0.93, coronal MD, 0.08 mm, p = 0.89 and sagittal MD, 0.04 mm, p = 0.96). The agreement for the fracture classification as well as the inter- and intra-rater agreement was excellent (range κ 0.92-0.98 (95% CI 0.96-0.99)).

CONCLUSION

Assessment of mandibular fractures was feasible and accurate using CT-like MRI based on a 3D T1 GRE sequence and is comparable to conventional CT.

CLINICAL RELEVANCE

For the assessment of acute mandibular fractures, CT-like MRI might become a useful alternative to CT in order to reduce radiation exposure particularly in young patients.

Blood flow analyses by intraoperative transit-time flow measurements of free flaps for head and neck reconstructions: A prospective single-center study

BACKGROUND

The behavior of blood flow changes within free flaps following microvascular anastomosis is not well described in the literature. The aim of this study was to determine the immediate blood flow behavior of different free flaps as reference values for various clinical applications.

METHODS

Intraoperative transit-time flow measurements were performed on patients receiving free flap transfer in the head and neck area comprising radial forearm flaps (RFF), peroneal artery perforator flaps (PAP), anterolateral thigh flaps (ALT), vastus lateralis flaps (VLF), parascapular flaps (PSF), latissimus dorsi flaps (LDF), fibula free flaps (FFF), deep circumflex iliac artery flaps (DCIA), and scapular flaps (SF). In accordance with a structured protocol, measurements took place at the pedicle directly before flap harvesting and at the recipient vessels 1 h after flap transfer. Heart rate, transplant weight, and other patient characteristics were recorded and analyzed.

RESULTS

A total of 129 were enrolled, comprising 66 RFF, 8 ALT, 6 PAP, 11 VLF, 3 PSF, 2 LDF, 24 FFF, 7 DCIA, and 2 SF. In most of the transplant groups, arterial perfusion increased after anastomosis at the recipient site. The arterial pulsatility index developed indirectly proportionally to arterial blood flow, whereas venous blood drainage did not show any statistically significant changes. Muscle flaps had the highest arterial perfusion before flap transfer. Composite transplants with hard and soft tissue presented the greatest increase in arterial perfusion. The lowest arterial blood flow after anastomosis was measured in PAP and RFF. In contrast, RFF and PAP presented the highest arterial perfusion per 100 g transplant weight.

CONCLUSIONS

Arterial perfusion changed, whereas venous blood flow did not show any statistically significant variations in any transplant group. Perfusion of free flaps does not only depend on the recipient vessel and the recipient bed, but also on flap-specific anatomy and physiology.

Conditioning of microvascular venous flaps in rats

Venous-only perfusion flaps have not been used widely because of the associated high failure rate. Tissue conditioning offers a broad scope of techniques that can be applied pre-, peri-, or postoperatively to promote the adaptation of the affected tissue to any subsequent stress. This study aimed to assess the survival rates associated with a pure venous perfusion flap and investigate whether the timing of the vascular conditioning can affect free flap survival. Forty-four rats were included in the experiment. Group I underwent veno-arterial anastomoses with epigastric graft with pure venous perfusion without tissue conditioning. Groups II and III were pretreated for 7 or 14 days with ischemic conditioning. These groups were compared with a control group (group IV) of conventionally perfused flaps. After the initial surgery, all flaps were assessed clinically, photometrically, and by indocyanine green videoangiography. The flap success rates were 0% in group I, 49.97% ± 24.34% in group II, and 64.95% ± 20.36% in group III. The control group showed an overall survival of 89.3% ± 6.51%. With suitable conditioning, pure venous blood supply can provide adequate perfusion in the rat epigastric flap model. The timing of vascular conditioning appears to be critical for flap survival.

Superficial Temporal Artery and Vein as Alternative Recipient Vessels for Intraoral Reconstruction With Free Flaps to Avoid the Cervical Approach With the Resulting Need for Double Flap Transfer in Previously Treated Necks

Background

Microvascular reconstruction remains challenging in previously operated and irradiated patients, especially when double flaps seem to be the only solution due to osteoradionecrosis. An alternative reconstructive option could be microvascular anastomosis to the temporal vessels to avoid the obligatory cervical incision.

Methods and Materials

All consecutive cases between January 2013 and 2020 that underwent either mandibular resection and reconstruction with a free fibula flap (FFF) and another soft tissue flap (group I) or pure intraoral resection and reconstruction with an FFF or radial forearm flap (RFF) with temporal microvascular anastomosis (group II) were included. Patients’ general information, indication and extent of surgery, time of ischemia, time of total surgery, and duration of hospital stay as well as incidence of complications were retrospectively recorded and analyzed.

Results

Seventeen (group I) and 11 (group II) cases were included. In group I, FFF was combined with RFF (n = 9), anterolateral thigh flap (ALT, n = 7), or latissimus dorsi flap (n = 1). Group II consisted of six FFFs and five RFFs. Operation time and hospitalization duration were significantly shorter in group II (p < 0.001 and p = 0.025), whereas ischemic time of FFF was significantly shorter in group I (p = 0.002). All patients in group I required a tracheostomy, while only four cases in group II did (p = 0.004). The complication rate regarding hematoma removal, revision of anastomosis, flap loss, delirium, sepsis, pleural effusion, pneumonia, and pulmonary artery embolism showed no significant differences between the two groups.

Conclusions

The superficial temporal vessels served as versatile recipient vessels for intraoral mandibular and soft tissue reconstruction and led to reduced operation time, hospitalization duration, and indication for a primary tracheostomy. Thus, this approach may help to avoid cervical incision for reconstruction in irradiated patients.

Results of a Clinical Scoring System Regarding Symptoms and Surgical Treatment of Isolated Unilateral Zygomatico-Orbital Fractures: A Single-Centre Retrospective Analysis of 461 Cases

Systematic assessment of computed tomography (CT) scans and clinical symptoms is necessary to quickly indicate the correct treatment of zygomatico-orbital (ZMO) fractures. For this purpose, a clinical scoring system (=Clinical Score) was developed and correlated with CT scans to analyse its validity. Every operated, isolated, and unilateral ZMO fracture between January 2012 and December 2016 was screened retrospectively, including patient and treatment data. All available CT scans were analysed, and the grade of dislocation was measured for each case and plane. Four hundred and sixty-one cases were included and showed a median surgery time of 66.0 min (5.0−361.0) and a median postoperative hospital stay of three days (0−25). The distribution of gender, aetiologies and age groups was significantly different (each p = 0.001), and the aetiology had a significant influence on the Clinical Score (p = 0.038). The degree of dislocation in the coronary and sagittal planes correlated significantly with the Clinical Score with regard to the orbital involvement (p < 0.001, ρ = 0.566; p < 0.001, ρ = 0.609). The simple, quick, and easy-to-apply Clinical Score showed a significant correlation with the most important planes in CT scans as well as with the clinical course. It may facilitate fast risk stratification of the patient. However, the validity of the proposed score in determining indications must now be evaluated in a prospective setting, including both operated and non-operated fractures.

In-House, Open-Source 3D-Software-Based, CAD/CAM-Planned Mandibular Reconstructions in 20 Consecutive Free Fibula Flap Cases: An Explorative Cross-Sectional Study With Three-Dimensional Performance Analysis

Background

Mandibular reconstruction is conventionally performed freehand, CAD/CAM-assisted, or by using partially adjustable resection aids. CAD/CAM-assisted reconstructions are usually done in cooperation with osteosynthesis manufacturers, which entails additional costs and longer lead time. The purpose of this study is to analyze an in-house, open-source software-based solution for virtual planning.

Methods and Materials

All consecutive cases between January 2019 and April 2021 that underwent in-house, software-based (Blender) mandibular reconstruction with a free fibula flap (FFF) were included in this cross-sectional study. The pre- and postoperative Digital Imaging and Com munications in Medicine (DICOM) data were converted to standard tessellation language (STL) files. In addition to documenting general information (sex, age, indication for surgery, extent of resection, number of segments, duration of surgery, and ischemia time), conventional measurements and three-dimensional analysis methods (root mean square error [RMSE], mean surface distance [MSD], and Hausdorff distance [HD]) were used.

Results

Twenty consecutive cases were enrolled. Three-dimensional analysis of preoperative and virtually planned neomandibula models was associated with a median RMSE of 1.4 (0.4–7.2), MSD of 0.3 (-0.1–2.9), and HD of 0.7 (0.1–3.1). Three-dimensional comparison of preoperative and postoperative models showed a median RMSE of 2.2 (1.5–11.1), MSD of 0.5 (-0.6–6.1), and HD of 1.5 (1.1–6.5) and the differences were significantly different for RMSE (p < 0.001) and HD (p < 0.001). The difference was not significantly different for MSD (p = 0.554). Three-dimensional analysis of virtual and postoperative models had a median RMSE of 2.3 (1.3–10.7), MSD of -0.1 (-1.0–5.6), and HD of 1.7 (0.1–5.9).

Conclusions

Open-source software-based in-house planning is a feasible, inexpensive, and fast method that enables accurate reconstructions. Additionally, it is excellent for teaching purposes.

Comparison between Different Perforator Imaging Modalities for the Anterolateral Thigh Perforator Flap Transfer: A Prospective Study

BACKGROUND

 Perforator imaging is routinely performed before perforator flap harvest. Hand-held Doppler (hhD) and color duplex ultrasonography (CDU) are currently the most popular radiation-free methods for this purpose that can be applied by the surgeon alone. The aim of this study was to compare the accuracy, reliability, and feasibility of hhD and CDU with indocyanine green angiography (ICGA) in the anterolateral thigh perforator flap (ALTPF).

METHODS

 All consecutive ALTPF procedures between May 2017 and April 2018 were included in this prospective study. The perforators were visualized by three investigators independently and randomized, applying hhD, CDU, and ICGA. The presence and the distance to the identified perforator were registered. Further, body mass index (BMI), American Society of Anesthesiologists-status, and the patient's history regarding smoking, alcohol use, and diabetes mellitus were registered alongside gender and age to analyze possible confounders.

RESULTS

 A total of 12 patients were enrolled with a median age of 67 (52-87) years. In total, 30 perforators were detected intraoperatively as well as with the ICGA. The latter visualized the perforators significantly more precisely than hhD and CDU (p < 0.001 and p = 0.001). The sensitivity and positive predictive value were 67 and 62% for hhD, 73 and 64% for CDU, and 100 and 100% for ICGA, respectively.

CONCLUSION

 According to this study, ICGA visualized perforators more accurately than the standard methods hhD and CDU. Further, it was associated with the highest sensitivity and positive predictive value. ICGA consistently delivered excellent results, whereas hhD and CDU showed variability.

Alterations in Surgically Created Intimal Lesions: An Observation Study in the Aortic Rat Model

BACKGROUND

 Intimal injury in microvessels due to common risk factors such as atherosclerosis or inadequate manipulation are known to have a major impact on developing thrombosis and eventually vascular obstruction. Understanding of these injuries is therefore of great significance to prevent far-reaching consequences such as flap loss in free tissue transfer. It was the aim of this study to evaluate artificially induced intimal lesions with focus on alteration in size and configuration.

METHODS

 Intimal defects were created surgically in the abdominal aorta of 30 male Wistar rats. After planimetric measurement of the defect sizes, configuration of defects were classified as round, horizontal, or vertical. Seven days postoperatively, the rats underwent a second-look surgery. Finally, the abdominal aorta was harvested, and the endothelial defects were reevaluated concerning size and configuration using a defined pattern.

RESULTS

 The mean defect size created intraoperatively was 1.68 ± 0.6 mm². The classification of the defects configurations resulted in 43.3% round, 20% horizontal, and 36.7% vertical defects. Reevaluation at 7 days after surgery showed defect shrinkage in 96.7% in total and 42.8% averaging due to reendothelialization. A shift in defect configuration was detected in 56.7%, the strongest being in vertical defect configurations (100%). Vascular occlusion did not occur in any of the specimen.

CONCLUSION

 Intimal injuries undergo a fast repair process in terms of size reduction and configuration modification due to reendothelialization. Especially vertical defects, representing a great risk for thrombus formation, convert into lower risk horizontal defect configurations. In high-flow vessels such as the rat aortas, small endothelial damage seems to have no significant impact to produce complete vascular occlusion. Still, all efforts should be made to avoid any kind of intimal injury.

In vivo perfusion of free skin flaps using extracorporeal membrane oxygenation

BACKGROUND

The vessel-depleted, irradiated, and frozen neck, as well as severe atherosclerosis of recipient vessels represent challenging problems in free flap transfer. Extracorporeal free flap perfusion theoretically allows free flap reconstructions in the absence of local donor vessels, but is associated with a number of technical issues. In this study, a novel technique is presented using a commercially available system for extracorporeal membrane oxygenation (ECMO), modified for small blood volumes.

METHODS

After preclinical testing, an ECMO system certified for lung support was used to establish blood flow through the flap's artery with oxygenation, decarboxylation and warming of diluted packed blood cells. Venous blood was allowed to flow passively into a separate container. Perfusion was performed for 15 min at intervals of 4 h over 4-6 days.

RESULTS

Five patients with soft tissue defects requiring free flap reconstruction were included. Either primarily thinned anterolateral thigh (ALT) flaps (n = 3) or radial forearm flaps (n = 2) were used. We observed infection of the perfusate, with consequent subtotal flap loss, in one patient, complete epithelial loss in two patients, venous congestion in one case, and almost uneventful healing in the fifth patient. With conservative wound care and a split thickness skin graft in one case, stable wound coverage was achieved in all patients except one, who had secondary healing. None of the patients required a second flap for sufficient coverage.

CONCLUSIONS

The technique described is associated with the risks of infection, flap congestion, nutritive hypoperfusion, and consequent tissue loss. Nevertheless, stable defect closure seems to be achievable even in patients with depleted recipient vessels.

Effect of Segment Length and Number of Osteotomy Sites on Cancellous Bone Perfusion in Free Fibula Flaps

BACKGROUND

 Indocyanine green (ICG) videoangiography is routinely used to evaluate skin and organ perfusion and to assess patency rates of microvascular anastomoses. This study uses ICG angiography as a novel approach to qualitatively and quantitatively evaluate bone perfusion of microvascular fibula grafts intraoperatively and to assess the effect of fibula segment length and number of osteotomies on bone perfusion.

METHODS

 All patients planned for mandible reconstruction using a microvascular fibula graft between January 2013 and May 2017 were considered for this study. ICG videoangiography of cancellous bone perfusion was performed using a handheld ICG camera. Videos were analyzed, and a perfusion curve was generated. Peak enhancement, time to peak, slope, and wash-in area under the curve were extracted; rise time, wash-in rate (WiR), and wash-in perfusion index were calculated. Results were statistically analyzed with regard to distal fibula segment length and number of osteotomy sites.

RESULTS

 Thirty-nine patients (age 59 ± 8 years) were included in the study. Mandible reconstruction was achieved with 1 (n = 15), 2 (n = 13), or 3 (n = 11) fibula segments. The WiR was 6.4 ± 2.3 and 4.4 ± 0.2 before and after proximal osteotomy, respectively. The wash-in perfusion index was 114.2 ± 48.4 before and 84.4 ± 20.0 after proximal osteotomy. Bone perfusion was significantly reduced after additional proximal osteotomies. Both the segment length and number of proximal osteotomies correlated with bone perfusion, with longer segments and fewer osteotomies showing higher perfusion.

CONCLUSION

 This study demonstrates the feasibility of cancellous bone perfusion analysis using ICG and can serve as a basis for future bone perfusion studies. Additional osteotomies and short segment length negatively affects cancellous bone perfusion of the distal fibula segment in free fibula flaps. The extent to which the observed decrease in arterial inflow to the distal fibula segment affects the further course of healing needs to be addressed in future studies.

The possibilities of a portable low-budget three-dimensional stereophotogrammetry system in neonates: a prospective growth analysis and analysis of accuracy

Background

With the technical development, portable three-dimensional (3D) photogrammetry systems are becoming more en vogue because of cost-effectiveness and comparable accuracy to common stationary 3D systems. The purpose of the study was to evaluate the feasibility and accuracy of a low-budget portable system for 3D image acquisition with special regard to the gracile nasal region in neonates. Furthermore, the study aimed to establish a 3D data set of the first 180 days post partum.

Methods

Thirty-three healthy, full-term newborn were enrolled and 3D photographs were prospectively taken monthly with a portable low-budget 3D stereophotogrammetry system (FUEL3D® SCANIFY®) for six months. In the third month, age-matched and corresponding 3D models were acquired by taking an impression of the perinasal area. The resulting plaster models were scanned (3Shape D700, 3Shape® A/S, Denmark). Three examiners analyzed independently 21 defined landmarks of the generated Standard Tessellation Language files with regard to accuracy by using 3dMDvultus™ software. A semi-automatic 3D best-fit analysis of 3D photo and plaster models were performed by using Geomagic® and the Root Mean Squared (RMS) errors were calculated.

Results

Statistically significant changes of midfacial distances and angles with a focus on nasal growth during the first 180 days postpartum could be specified in absolute and relative dimensions. Best-fit analysis in the third month revealed a RMS error of 0.72 ± 0.22 mm with a mean standard deviation of 0.71 ± 0.21 mm.

Conclusions

The analyzed portable 3D stereophotogrammetry system is a feasible methodology with good accuracy, even in newborn. A description of the growth as well as the establishment of a 3D data set was performed. Its implementation for basic documentation for example in cleft patients is possible and might reduce the need for impressions and facilitate the communications with parents and the interdisciplinary team.

Detection of thrombosis in microvessels with indocyanine green videoangiography

Atherosclerosis is a systemic condition that is responsible for many diseases, and becomes a problem in cases where plaques form at several sites. The formation of a thrombotic embolus may jeopardise vascular operations, including microvascular anastomoses in replantation procedures or free tissue transfers. A mobile imaging tool for the detection of thrombosis preoperatively or intraoperatively would be valuable. An intimal injury, simulating removal of atherosclerotic plaques, was made microsurgically in 60 rat aortas, and results were analysed macroscopically, histologically, and with intraoperative indocyanine green (ICG) videoangiography immediately postoperatively. The Spearman and Pearson correlation tests were used to compare the three techniques. The sensitivity and specificity of ICG videoangiography was calculated in relation to both macroscopic and histological results. Detection of thrombosis was possible in 25 cases, and in 18 cases no thrombosis was correctly diagnosed by all methods used. In 31 of 60 specimens formation of thrombus was detected histologically, and in 29 of 60 examinations it was detected clinically, which yielded a correlation of 93.5% between the two examinations. Macroscopic analysis correlated better with ICG videoangiography (sensitivity 86.2% and specificity 64.5%) than histological observations (sensitivity 80.6% and specificity 62.1%). There was a significant correlation among all comparisons (each p≤0.001) with correlation indexes of 0.94, 0.52, and 0.44 for macroscopic/histological, clinical/ICG videoangiographic, and ICG videoangiographic/histological results, respectively. Our results show that ICG videoangiography is an important method for the detection of formation of acute thrombi and may be an important tool in vascular procedures.

Multimodal analysis using flowmeter analysis, laser-Doppler spectrophotometry, and indocyanine green videoangiography for the detection of venous compromise in flaps in rats

Venous congestion results in tissue damage and remains the most common failure of free microvascular transfer if it is not recognized early. The purpose of this experimental study was to evaluate venous congestion and describe the findings with two different monitoring tools. A standardized epigastric flap was raised, and total occlusion of the draining vein was temporarily applied for 4, 5, 6, or 7 h. Blood flow measurements, including laser-Doppler flowmetry, and tissue spectrophotometry (O2C) and indocyanine green (ICG) videoangiography using the FLOW^® 800 tool, were performed systematically after each surgical step, an interval of venous occlusion, and 1 week of clinical observation. Both monitoring tools were capable of detecting acute venous occlusion. ICG videoangiography data showed a significant decrease in the first and second maximum, and the area under the curve, during venous occlusion, whereas hemoglobin levels in the O2C analysis remained stable. Changes in fluorescence values in border areas of the flap correlated significantly with the incidence of necrosis. O2C data later showed significant correlation with the area of necrosis, and more individual changes during flap monitoring. ICG videoangiography might therefore be useful in the prediction of flap necrosis in critical areas of perfusion.

Form and Size Matter: Increased Risk of Thrombosis in Microvessels with Surgically Created Endothelial Lesions

Background Atherosclerosis is a known risk factor for flap loss in microsurgery. Several microsurgical techniques, like plaque removal, have been proposed for atherosclerotic vessels, but these techniques often induce intimal injuries. The aim of this study was to investigate the impact of various endothelial defects on the risk of thrombosis in a rat acute intimal injury model. Methods Endothelial defects of various forms and sizes were created in the abdominal aorta of 30 male Wistar rats following a strict protocol. Defect sizes were measured and classified as round, horizontal, or vertical based on their configuration. An hour after reestablishing the blood flow, the abdominal aorta was harvested and the operation site was assessed for signs of thrombosis clinically and using light microscopy. Univariate and multiple linear regression analysis were performed to identify possible influencing factors on thrombosis. Results The mean defect size was 2.65 ± 1.19 mm². Intimal lesions were classified as round in 36.7%, horizontal in 33.3%, and vertical in 30% of specimens. Thrombus formation was detected in 46.7% clinically and in 50% histologically. Univariate regression analysis revealed that defect size (p = 0.048) and vertical form (p = 0.017) were significantly associated with thrombus formation. Multiple regression analysis corroborated vertical defects as a risk factor for thrombosis (p = 0.03). Conclusion Endothelial injuries are associated with a high risk of thrombosis with highest risks associated with vertical defects. Arteries should be carefully examined for intimal defects before microvascular anastomosis, especially in the atherosclerotic patient.

Indocyanine green videoangiography-assisted prediction of flap necrosis in the rat epigastric flap using the flow® 800 tool

BACKGROUND

The decision to re-operate on a potentially ischemic free flap remains challenging. Indocyanine green videoangiography (ICG) with the FLOW^® 800 tool is a method which allows an immediate qualitative conclusion about the patency of an anastomosis. Is it also able to predict the outcome of potentially compromised vascular free flaps?

MATERIALS AND METHODS

An epigastric flap was raised and repositioned in 79 rats. Intraoperative fluorescence angiography was performed using ICG videoangiography and the FLOW^® 800 tool was applied. Six regions of interest were positioned systematically over the flap, changes of the ICG fluorescence were color coded with respect to time and 474 measurements were performed. The flap was clinically monitored for one week and the resulting necrotic areas were correlated with the ICG/FLOW^® 800 results.

RESULTS

Mean intensity of clinically vital areas was 83.39 ± 50.96 arbitrary units (AU) and 37.33 ± 15.14 AU in necrotic areas. The receiver operating characteristic curve and Youden-Index analysis revealed that the optimal cutoff for the maximal intensity of ICG after FLOW^® 800 analysis was ≤ 61.733 for the prediction of flap necrosis and > 61.733 for the prediction of flap survival (P < 0.0001; 95% CI = 0.85-0.91; Youden-Index: 0.67). The maximal intensity of ICG angiography had a specificity of 96.1% and sensitivity of 71.4%. The positive predictive value was 97.46% and the corresponding negative predictive value was 61.34%.

CONCLUSION

This demonstrates the potential additional value of ICG videoangiography including FLOW^® 800 analyses in the postoperative monitoring of transplanted flaps. © 2016 Wiley Periodicals, Inc. Microsurgery 37:235-242, 2017.

Development of an Extracorporeal Perfusion Device for Small Animal Free Flaps

Background

Extracorporeal perfusion (ECP) might prolong the vital storage capabilities of composite free flaps, potentially opening a wide range of clinical applications. Aim of the study was the development a validated low-cost extracorporeal perfusion model for further research in small animal free flaps.

Methods

After establishing optimal perfusion settings, a specially designed extracorporeal perfusion system was evaluated during 8-hour perfusion of rat epigastric flaps followed by microvascular free flap transfer. Controls comprised sham-operation, ischemia and in vivo perfusion. Flaps and perfusate (diluted blood) were closely monitored by blood gas analysis, combined laser Doppler flowmetry and remission spectroscopy and Indocyanine-Green angiography. Evaluations were complemented by assessment of necrotic area and light microscopy at day 7.

Results

ECP was established and maintained for 8 hours with constant potassium and pH levels. Subsequent flap transfer was successful. Notably, the rate of necrosis of extracorporeally perfused flaps (27%) was even lower than after in vivo perfusion (49%), although not statistically significant (P = 0,083). After sham-operation, only 6% of the total flap area became necrotic, while 8-hour ischemia led to total flap loss (98%). Angiographic and histological findings confirmed these observations.

Conclusions

Vital storage capabilities of microvascular flaps can be prolonged by temporary ECP. Our study provides important insights on the pathophysiological processes during extracorporeal tissue perfusion and provides a validated small animal perfusion model for further studies.

Microvascular anastomosis using modified micro-stents: a pilot in vivo study

INTRODUCTION

Microvascular sutured anastomosis remains the gold standard in microvascular flap surgery but is technically challenging, time-consuming, and sometimes unreliable. The goal of our study has been to develop a microvascular stenting system that can be used for microvascular anastomosis, even without the use of a microscope.

MATERIALS AND METHODS

Custom-made stainless-steel stents were used to re-establish vessel continuity after the severance of the abdominal aortic vessel in nine rats. At 30 min after re-opening the blood flow, Doppler flowmetry and indocyanine green (ICG) angiography were used to assess vessel patency, and vessels were inspected microscopically for signs of thrombosis.

RESULTS

Eight of the nine animals survived the procedure. In one case, the abdominal aorta was torn during balloon dilation of the stent. Four out of the nine stent anastomoses showed an excellent fit. In the remaining four cases, a collagen membrane and fibrin glue were successfully used to stop vascular leakage. However, these additional steps might have had a negative impact on vessel patency, and thrombus formation impaired blood flow completely in one case.

CONCLUSION

Microvascular stent anastomosis is feasible and might in some cases be superior to standard sutured anastomosis. However, a number of technical difficulties remain to be addressed, and long-term results are not yet available.

Introduction of a microsurgical in-vivo embolization-model in rats: the aorta-filter model

Vascular thrombosis with subsequent distal embolization remains a critical event for patients. Prevention of this life-threatening event can be achieved pharmacologically or mechanically with intravascular filter systems. The ability to evaluate the risk of embolization of certain techniques and procedures in vascular and microvascular surgery, such as, tissue glue or fibrin based haemostatic agents lacks convincing models. We performed 64 microvascular anastomoses in 44 rats, including 44 micro-pore polyurethane filter-anastomoses and 20 non-filter anastomoses. The rats were re-anesthetized and the aorta was re-exposed and removed four hours, three, seven, fourteen, thirty-one days, and six months postoperatively. The specimens were examined macro- and microscopically with regard to the appearance of the vessel wall, condition of the filter and the amount of thrombembolic material. Typical postoperative histopathological changes in vessel architecture were observed. Media necrosis was the first significant change three days postoperatively. Localized intimal hyperplasia, media necrosis, increase of media fibromyocytes and adventitial hypercellularity were seen to a significant extent at day seven postoperatively. Significant neovascularization of adventitia adjacent to the filter was seen after 14 days. A significant amount of thrombotic material was seen after four hours, three and 14 days interval. Only three intravascular filters became completely occluded (6.82%). The aorta-filter-anastomosis model appeared to be a valid in-vivo model in situations at risk for thrombembolic events, for microsurgical research and allowed sensitive analysis of surgical procedures and protection of the vascularized tissue. It may be suitable for a wide range of in-vivo microvascular experiments particularly in the rat model.

Objective qualitative and quantitative assessment of blood flow with near-infrared angiography in microvascular anastomoses in the rat model

Intraoperative near-infrared indocyanine-green (ICG) angiography enables the visualization of microvascular perfusion and may help in the early detection of complications. The purpose of the present study was to examine whether the effect of microvascular stenoses can be quantitatively assessed by analysis of ICG-angiography in a microvascular model. Graded stenoses and total vessel occlusion of the carotid, aorta, and femoral arteries were created in 25 Wistar rats. Stenoses were graded to reduce arterial flow by 25%, 50%, 75%, and 100% of baseline flow as measured by transit-time flowmeter analyzing the emission signal of the ICG detected and investigated by the mathematical software tool (FLOW 800). ICG angiography was performed to assess vessel perfusion and flow curves were analyzed and correlated with the stenosis rate. A total of 576 investigations were performed. The area under the curve (P < 0.001), first and second maximum (P < 0.001), and the maximum slope to the first maximum (P < 0.001) were found to be of high prognostic value in evaluating the different flow patterns. Differences were displayed in comparisons by the maximum intensity of the ICG-concentrations. The maximum slope to the second maximum was found to be predictive in selected vessel types, and specific changes of the flow curve were found to indicate compromised vascular flow. The FLOW 800 tool applied for ICG angiography has shown to be a quick and reliable method for assessing blood flow in vessels in this study. The dynamic assessment of the ICG signal allows reliable identification of microanastomotic complications with the described parameters.

Peripheral nerve reconstruction with collagen tubes filled with denatured autologous muscle tissue in the rat model

Conventional nerve conduits lack cellular and extracellular guidance structures critical for bridging larger defects. In this study, an exogenous matrix for axonal regeneration was provided by pretreated muscle tissue. In 24 rats, 14-mm sciatic nerve segments were resected and surgically reconstructed using one of the following methods: autograft (AG); bovine type I collagen conduit; (MDM) collagen tube filled with modified denatured autologous muscle tissue. For 8 weeks, functional regeneration was evaluated by footprint and video gait analysis. Evaluation was complemented by electrophysiology, as well as qualitative and quantitative structural assessment of nerves and target muscles. Group AG was superior both structurally and functionally, showing higher axon counts, a more normal gait pattern, and less severe muscle atrophy. Fiber quality (fiber size and myelin thickness) was highest in group MDM, possibly related to the myelin-producing effect of muscular laminin. However, axon count was lowest in this group, and ultrastructural analysis of the denatured muscle tissue showed areas of incomplete denaturation that had acted as a mechanical barrier for regenerating axons. In light of these results, the often advocated use of muscular exogenous matrix for peripheral nerve reconstruction is reviewed in the literature, and its clinical application is critically discussed. In conclusion, combined muscle tubes may have a positive influence on nerve fiber maturation. However, muscle pretreatment is not without risks, and denaturation processes need to be further refined.

[Mandibular osteoma in a case of Gardner's syndrome]

Gardner's syndrome is characterized by the triad of intestinal polyposis accompanied by multiple hard- and soft-tissue tumors. Untreated, all patients will develop gastrointestinal cancer by the age of 40. Although incurable, progression can be prevented by close monitoring and prophylactic colectomy to prevent malignancy. Multiple osteomas of the head and jaw bones are common extraintestinal manifestations of Gardner's syndrome and can be helpful in the diagnostic work-up. The disease pattern should be known to the treating physician, since extraintestinal manifestations usually occur long before intestinal polyposis and early diagnosis is critical for the prognosis.