Simulating Surgical Skills in Animals: Systematic Review, Costs & Acceptance Analyses

Background:Modern surgery demands high-quality and reproducibility. Due to new working directives, resident duty hours have been restricted and evidence exists that pure on-the-job training provides insufficient exposure. We hypothesize that supplemental simulations in animal models provide a realistic training to augment clinical experiences. This study reviews surgical training models, their costs and survey results illustrating academic acceptance. Methods:Animal models were identified by literature research. Costs were analyzed from multiple German and Austrian training programs. A survey on their acceptance was conducted among faculty and medical students. Results:915 articles were analyzed, thereof 91 studies describedin-vivoanimal training models, predominantly for laparoscopy (30%) and microsurgery (24%). Cost-analysis revealed single-training costs between 307euro and 5,861euro depending on model and discipline. Survey results illustrated that 69% of the participants had no experience, but 66% would attend training under experienced supervision. Perceived public acceptance was rated intermediate by medical staff and students (4.26;1-low, 10 high). Conclusion:Training in animals is well-established and was rated worth attending in a majority of a representative cohort to acquire key surgical skills, in light of reduced clinical exposure. Animal models may therefore supplement the training of tomorrow's surgeons to overcome limited hands-on experience until virtual simulations can provide such educational tools

Promoting axonal regeneration following nerve surgery: a perspective on ultrasound treatment for nerve injuries

Nerve injury is often associated with limited axonal regeneration and thus leads to delayed or incomplete axonal reinnervation. As a consequence of slow nerve regeneration, target muscle function is often insufficient and leads to a lifelong burden. Recently, the diagnosis of nerve injuries has been improved and likewise surgical reconstruction has undergone significant developments. However, the problem of slow nerve regeneration has not been solved. In a recent meta-analysis, we have shown that the application of low-intensity ultrasound promotes nerve regeneration experimentally and thereby can improve functional outcomes. Here we want to demonstrate the experimental effect of low intensity ultrasound on nerve regeneration, the current state of investigations and its possible future clinical applications

Selective Denervation of the Facial Dermato-Muscular Complex in the Rat: Experimental Model and Anatomical Basis

The facial dermato-muscular system consists of highly specialized muscles tightly adhering to the overlaying skin and thus form a complex morphological conglomerate. This is the anatomical and functional basis for versatile facial expressions, which are essential for human social interaction. The neural innervation of the facial skin and muscles occurs via branches of the trigeminal and facial nerves. These are also the most commonly pathologically affected cranial nerves, often requiring surgical treatment. Hence, experimental models for researching these nerves and their pathologies are highly relevant to study pathophysiology and nerve regeneration. Experimental models for the distinctive investigation of the complex afferent and efferent interplay within facial structures are scarce. In this study, we established a robust surgical model for distinctive exploration of facial structures after complete elimination of afferent or efferent innervation in the rat. Animals were allocated into two groups according to the surgical procedure. In the first group, the facial nerve and in the second all distal cutaneous branches of the trigeminal nerve were transected unilaterally. All animals survived and no higher burden was caused by the procedures. Whisker pad movements were documented with video recordings 4 weeks after surgery and showed successful denervation. Whole-mount immunofluorescent staining of facial muscles was performed to visualize the innervation pattern of the neuromuscular junctions. Comprehensive quantitative analysis revealed large differences in afferent axon counts in the cutaneous branches of the trigeminal nerve. Axon number was the highest in the infraorbital nerve (28,625 ± 2,519), followed by the supraorbital nerve (2,131 ± 413), the mental nerve (3,062 ± 341), and the cutaneous branch of the mylohyoid nerve (343 ± 78). Overall, this surgical model is robust and reliable for distinctive surgical deafferentation or deefferentation of the face. It may be used for investigating cortical plasticity, the neurobiological mechanisms behind various clinically relevant conditions like facial paralysis or trigeminal neuralgia as well as local anesthesia in the face and oral cavity

Perioperative Risk Factors for Prolonged Blood Loss and Drainage Fluid Secretion after Breast Reconstruction

Background: Surgical breast reconstruction is an integral part of cancer treatment but must not compromise oncological safety. Patient-dependent risk factors (smoking, BMI, etc.) are said to influence perioperative outcomes and have often been investigated. Here, we analyzed independent perioperative risk factors for increased postoperative blood loss or drainage fluid volume loss and their possible impact. Methods: Patients undergoing breast reconstructions after breast cancer with either tissue expanders, definitive breast implants, or autologous breast reconstruction were analyzed. The collected data on patients’ characteristics, blood, and drainage fluid loss were correlated and statistically investigated. Results: Traditional patient-dependent risk factors did not influence blood loss or drainage volumes. On the contrary, patients with preoperative anemia had significantly higher drainage outputs compared to non-anemic patients (U = 2448.5; p = 0.0012). The administration of low molecular weight heparin showed a tendency of increased drainage output. Similar correlations could be seen in prolonged procedure time, all of which contributed to prolonged hospital stay (τb = 0.371; p < 0.00001). Conclusions: Preoperative anemia is one of the most critical factors influencing postoperative drainage fluid output. Previously assumed patient-dependent risk factors did not affect drainage output. Preoperative anemia must be monitored, and if possible, treated preoperatively to reduce postoperative morbidity

Acute and long-term costs of 268 peripheral nerve injuries in the upper extremity.

BACKGROUND:Peripheral nerve injury in the upper extremity is linked to high socioeconomic burden, yet cost-analyses are rare and from small cohorts. The objective of this study was to determine the costs and long-term socioeconomic effects of peripheral nerve injuries in the upper extremity in Germany. METHODS:We analyzed data of 250 patients with 268 work-related upper extremity nerve injuries from acute treatment to long-term follow-up on rehabilitation, sick-leave and disability-pension. RESULTS:Patients were on average 39.9±14.2 years old, male (85%) and mean inpatient treatment was 7±6 days. Location of nerve was 8% (N = 19) proximal to the wrist, 26% (N = 65) at the wrist and metacarpus, and 66% (N = 166) at phalangeal level. Acute in-patient treatment for (single) median nerve injury accounted for 66% with hospital reimbursement of 3.570€, ulnar nerve injury for 24% and 2.650€ and radial nerve injury for 10% and 3.166€, all including finger nerve injuries. The remaining were combined nerve injuries, with significantly higher costs, especially if combined with tendon 5.086€ or vascular injury 4.886€. Based on location, nerve injuries proximal to the wrist averaged 5.360±6.429€, at the wrist and metacarpus 3.534±2.710€ and at the phalangeal level 3.418±3.330€. 16% required rehabilitation with average costs of 5.842€ and stay of 41±21 days. Sick leave was between 11-1109 days with an average of 147 days with socioeconomic costs of 197€/day, equaling on average 17.640€. 30% received a mean yearly disability pension of 3.187€, that would account to 102.167€ per lifetime. CONCLUSION:This large German patient sample indicates that nerve injury has a major impact on function and employment, resulting in significant health care costs. Both proximal and distal nerve injuries led to long-term disability, subsequent sick-leave and in 30% to permanent disability pension. These data are determined to support future studies and health economical work on prevention, treatment and rehabilitation of these often small injuries with great consequences

Distal Nerve Transfers in High Peroneal Nerve Lesions: An Anatomical Feasibility Study

The peroneal nerve is one of the most commonly injured nerves of the lower extremity. Nerve grafting has been shown to result in poor functional outcomes. The aim of this study was to evaluate and compare anatomical feasibility as well as axon count of the tibial nerve motor branches and the tibialis anterior motor branch for a direct nerve transfer to reconstruct ankle dorsiflexion. In an anatomical study on 26 human body donors (52 extremities) the muscular branches to the lateral (GCL) and the medial head (GCM) of the gastrocnemius muscle, the soleus muscle (S) as well as the tibialis anterior muscle (TA) were dissected, and each nerve’s external diameter was measured. Nerve transfers from each of the three donor nerves (GCL, GCM, S) to the recipient nerve (TA) were performed and the distance between the achievable coaptation site and anatomic landmarks was measured. Additionally, nerve samples were taken from eight extremities, and antibody as well immunofluorescence staining were performed, primarily evaluating axon count. The average diameter of the nerve branches to the GCL was 1.49 ± 0.37, to GCM 1.5 ± 0.32, to S 1.94 ± 0.37 and to TA 1.97 ± 0.32 mm, respectively. The distance from the coaptation site to the TA muscle was 43.75 ± 12.1 using the branch to the GCL, 48.31 ± 11.32 for GCM, and 19.12 ± 11.68 mm for S, respectively. The axon count for TA was 1597.14 ± 325.94, while the donor nerves showed 297.5 ± 106.82 (GCL), 418.5 ± 62.44 (GCM), and 1101.86 ± 135.92 (S). Diameter and axon count were significantly higher for S compared to GCL as well as GCM, while regeneration distance was significantly lower. The soleus muscle branch exhibited the most appropriate axon count and nerve diameter in our study, while also reaching closest to the tibialis anterior muscle. These results indicate the soleus nerve transfer to be the favorable option for the reconstruction of ankle dorsiflexion, in comparison to the gastrocnemius muscle branches. This surgical approach can be used to achieve a biomechanically appropriate reconstruction, in contrast to tendon transfers which generally only achieve weak active dorsiflexion

Wirtschaftliche Aspekte in der Mikrochirurgie: Bericht zum Konsensus-Workshop der Deutschsprachigen Arbeitsgemeinschaft für Mikrochirurgie der peripheren Nerven und Gefäße – (DAM)

Im Zuge des zunehmenden Kostendrucks im Gesundheitssystem werden Therapien neben ihrer Qualität zunehmend auch hinsichtlich ihrer Wirtschaftlichkeit bewertet. Mikrochirurgische Eingriffe haben sich vor allem im Langzeitverlauf in vielen Bereichen als funktionell und ästhetisch überlegen gezeigt. Im Vergleich zu Alternativeingriffen sind sie aber auf Grund ihrer Komplexität sowie langen Operationszeiten und stationären Verweildauern mit hohen Kosten verbunden. Damit diese langfristig in hoher Qualität angeboten werden können, muss entsprechend von Seiten der Kostenträger, insbesondere auch bei interdisziplinären Eingriffen, eine adäquate, kostendeckende Vergütung erfolgen. Um einen korrekten DRG-Erlös zu erhalten sollten daher neben der Hauptdiagnose auch die relevanten Nebendiagnosen und Prozeduren richtig und vollständig dokumentiert werden. Auch der finanzielle Mehrwert eines interdisziplinären Eingriffs lässt sich durch die Erhöhung des Erlöses mit mikrochirurgischem Operationsanteil errechnen. Zwischen den Kliniken eines Krankenhauses sollte daher eine interdisziplinäre Erlösaufteilung stattfinden. Für eine faire und transparente interdisziplinäre Leistungsverrechnung existieren mehrere Modelle, mit denen alle beteiligten Kliniken einen Mehrwert erwirtschaften können. Leider bestehen an vielen Krankenhäusern unzureichende interdisziplinäre Vergütungsmodelle, welche eine qualitativ hochwertige, kostendeckende Patientenversorgung mit mikrochirurgischen Eingriffen erschweren. Ungeachtet des zunehmenden Kostendrucks und nicht medizinischer wirtschaftlicher Aspekte muss unser Handeln als Arzt immer die bestmögliche Patientenversorgung sicherstellen. = In addition to outcome assessments, cost effectiveness of surgical treatments becomes increasingly important. Both, insurance companies and hospital administrations aim for short and efficient procedures to reduce costs.Microsurgical procedures are often surpassing traditional treatment options in terms of function and aesthetics. However, they are more expensive as they require a high level of surgical expertise, more theatre capacity and longer inpatient treatment. Adequate reimbursement is mandatory, if we want to continuously perform these procedures with the best possible quality and outcome. To cover the case-related expenses of each specialty, multidisciplinary procedures require appropriate distribution of reimbursements to each department.The main diagnosis as well as all complications and relevant comorbidities should be documented to obtain the correct DRG. The additional financial benefit of a microsurgical procedure in a multidisciplinary case can be calculated by specifying the procedural increment in pay. Therefore, a fair distribution of revenues to each participating department should be performed. Different models exist, which lead to a benefit in compensation for all departments. Unfortunately, distribution of resources is still insufficiently managed in many hospitals, which hampers high quality multidisciplinary microsurgical procedures. Still, picking the best possible procedure for our patients, independently of financial incentives, is of utmost importance

Avian extremity reconstruction via osseointegrated leg-prosthesis for intuitive embodiment

Abstract For large avians such as vultures, limb loss leads to loss of ambulation and eventually death from malnutrition. Prosthetic devices may replace the limb, however, conventional prosthetic sockets are not feasible in feathered limbs and the extreme stress and strain of unreflected daily use in animals. Osseointegration is a novel technique, where external prosthetic parts are connected directly to a bone anchor to provide a solid skeletal-attachment. This concept provides a high degree of embodiment since osseoperception will provide direct intuitive feedback allowing natural use of the limb in gait and feeding. Here we demonstrate for the first time an osseointegrated bionic reconstruction of a limb in a vulture after a tarsometatarsal amputation with a longterm follow-up

Peripheral nerve transfers change target muscle structure and function

Selective nerve transfers surgically rewire motor neurons and are used in extremity reconstruction to restore muscle function or to facilitate intuitive prosthetic control. We investigated the neurophysiological effects of rewiring motor axons originating from spinal motor neuron pools into target muscles with lower innervation ratio in a rat model. Following reinnervation, the target muscle's force regenerated almost completely, with the motor unit population increasing to 116% in functional and 172% in histological assessments with subsequently smaller muscle units. Muscle fiber type populations transformed into the donor nerve's original muscles. We thus demonstrate that axons of alternative spinal origin can hyper-reinnervate target muscles without loss of muscle force regeneration, but with a donor-specific shift in muscle fiber type. These results explain the excellent clinical outcomes following nerve transfers in neuromuscular reconstruction. They indicate that reinnervated muscles can provide an accurate bioscreen to display neural information of lost body parts for high-fidelity prosthetic control.peerReviewe