Surgical simulation flexor tendon repair using Thiel cadavers: a comparison with formalin embalmed cadavers and porcine models

Which is more effective? Porcine tendon or 3D- printed flexor tendon? A study of model realism and educational utility in a flexor tendon repair workshop

Introduction

Animal models in orthopaedic surgical training have raised concerns about ethics and availability, prompting the search for non-animal alternatives. The 3D-printed silicone tendon model has emerged as a potential alternative due to its hygiene and reusability. This study aimed to compare the effectiveness of the two models for flexor tendon repair training.

Materials and methods

A survey involved 25 postgraduate trainees with no prior experience in flexor tendon repair. Porcine tendon models and 3D-printed models were used, with participants evaluating accuracy, understanding of pulley systems, joint flexion, tissue feel, and model realism. Repairs were evaluated by experienced surgeons, and participants completed a survey.

Results

Both models demonstrated satisfactory accuracy and realistic joint flexion. The porcine model scored higher in anatomical accuracy, while the 3D-printed model excelled in understanding pulley systems. The porcine model provided realistic tissue feel, while the 3D-printed model facilitated anatomy teaching. No significant difference was found in educational utility. The 3D-model was perceived as hygienic and odourless, whereas the porcine model offered better tendon handling. The 3D-model improved visualization of suture placement. Both models were equally accepted and recommended for training.

Conclusion

The 3D-printed silicone tendon model is a cost-effective and reproducible alternative to porcine models in flexor tendon repair training. Although the 3D-printed model has limitations in mimicking human tendons, it was equally effective in teaching suturing techniques and improving repair skills. Combining the porcine model and 3D-printed model provides a comprehensive approach to flexor tendon repair training, addressing the limitations of each model and enhancing the educational experience.

Validation of a novel simulated tendon model for core suture tendon repair

INTRODUCTION

Simulation training can develop surgical procedural skills in a safe environment. Able to offer high-intensity exposure, simulation is increasingly important as working time for surgeons becomes more protected. Materials used in simulated tendon repair play a critical role in the fidelity and face validity of the model. Although organic materials like porcine tendon are commonly used, non-organic materials offer advantages such as accessibility, reproducibility, cost-effectiveness and ease of use without the need for special licences or facilities. This study aims to establish the face, content and concurrent validity of using a novel silicone material in a simulated tendon repair model.

METHODS

Three tendon models, bathroom silicone sealant, DragonSkin® silicone and organic porcine tendons, were evaluated for concurrent validity through mechanical load to failure testing. Face and content validity were assessed, following participant repair of a DragonSkin® tendon, using a 5-point Likert scale for five clinically relevant parameters.

RESULTS

Significant differences in load to failure were observed among bathroom sealant, DragonSkin® and porcine tendon (11.1N, 31.7N and 56.2N; p < 0.001). Participant feedback on the DragonSkin® tendon indicated that it was suitably representative, easy to use and useful for training (agreement rates 58%, 75% and 83%, respectively). However, participants noted that the model did not handle or glide like human tendon (both 8% agreement).

CONCLUSION

DragonSkin® silicone is an adaptable and valid material for simulated tendon repair models. It is low cost, widely available and shows promise as a training tool. Future research will focus on exploring its effectiveness in training settings.

Construct validation of a novel synthetic tendon model used for assessing surgeon performance in a simulated core suture tendon repair technique

BACKGROUND

The strength of tendon repair is dependent on the quality of the core suture. Organic and synthetic materials have been used to simulate tendon repair for training; however, no model has undergone construct validation.

OBJECTIVES

To determine the construct validity of a novel synthetic tendon repair model.

METHODS

Synthetic silicone tendon models were used to simulate adult Achilles tendon (AT) and digital flexor tendon (FT). Participants were categorised into novice, intermediate, and advanced groups based on prior surgical experience. Participants repaired tendons using the modified Kessler technique. A validated motion analysis system was used to measure the duration, path length, and movement count during the simulated task. A global rating score was also used to assess the performance.

RESULTS

All participants in the novice (n = 12), intermediate (n = 8) and advanced (n = 11) groups completed the tasks. The results (mean±standard deviation) were duration (872 ± 335, 492 ± 257 and 357 ± 40 s), path length (9493 ± 3173, 6668 ± 1740 and 4672 ± 1228 cm), movement count (4974 ± 673, 4228 ± 259 and 3962 ± 69) and global rating (39 ± 13, 61 ± 14, 81 ± 5), respectively. The Kruskal-Wallis test was significant for all outcome measures (p < 0.01). Significant differences in duration and movement count were identified post-hoc in the AT model for each experience group (p < 0.05), and between novice and intermediate participants for FT repair (p < 0.04). Global rating was significantly different between all groups and was highly correlated with motion metrics (p < 0.01).

CONCLUSION

The results support construct validity of this novel simulated tendon repair model. The global rating scores may allow wide utility of this simulation. This model provides a valid and safe environment for surgical trainees to practice tendon repair with several cost, ethical and logistical benefits over animal tendon use. 248/250.

Implementation of a Near-Peer Surgical Anatomy Teaching Program into the Surgery Clerkship

OBJECTIVE

The objective of this study was to describe the implementation of Clinical Anatomy Mentorship Program (CAMP), a novel near-peer surgical anatomy teaching program, into the KU School of Medicine (KUSOM) Surgery Clerkship curriculum.

DESIGN

Prospective qualitative and quantitative study.

SETTING

Single institution, tertiary care hospital.

PARTICIPANTS

All M3s at KUSOM on their surgery clerkship were eligible for inclusion for the learner cohort, n = 106. A group of M4s self-identified as CAMP mentors were eligible for inclusion for the teacher cohort, n = 40.

RESULTS

M3s have statistically significant higher self-efficacy (p < 0.001) scores after participating in CAMP. Among open-ended comments written by M3s, significant themes highlighted that CAMP taught them a much-needed refresher on anatomy, gave them an introduction to surgical anatomy, and felt peer-to-peer teaching created a safe environment to ask questions. M4 mentors reported statistically significant (p < 0.001) increases in self-efficacy and confidence in teaching skills after teaching CAMP sessions. Among open-ended comments written by M4 mentors, significant themes highlighted that CAMP helped them develop their teaching skills and confidence in the operating room.

CONCLUSIONS

In line with current medical education practices, KUSOM has significantly decreased anatomy in the curriculum. We responded to this shift by implementing CAMP, designed to address specific medical student needs for a surgically oriented anatomy instruction. CAMP has been effective at addressing student concerns about anatomy knowledge gaps. CAMP has enhanced self-efficacy, anatomy knowledge, and operating room exposure in M3s, and self-efficacy, teaching skills, surgical anatomy knowledge, and surgical confidence in M4s.

Training on skin flap elevation in hand surgery using cadavers embalmed by the saturated salt solution method: effectiveness and usefulness

Thiel embalmed and fresh-frozen cadavers have been mainly used for hand surgery training. We held a training seminar on skin flap elevation using cadavers embalmed by the saturated salt solution method. This study aimed to evaluate the usefulness of such training and to validate the suitability of saturated salt solution-embalmed cadavers for hand surgery training. Participants were trained in elevation procedures for the oblique triangular, reverse digital artery, reverse radial forearm, and reverse dorsal metacarpal artery flaps. Forty-eight surgeons participated in three seminars (one held in 2017, 2018, and 2019 each). A self-assessment of the participants' confidence levels for their surgical skills was performed before and immediately after the seminar, and the suitability of saturated salt solution-embalmed cadavers was determined in terms of visual perception, tactility, comparison with real-world surgical settings, and usefulness. The confidence level for all skills increased immediately after the seminar. The surgeons reported that the visual perception and tactility of the saturated salt solution-embalmed cadavers were comparable to those of a living body, and the cadavers were rated higher with respect to their usefulness. Hand surgery seminars using cadavers embalmed by the saturated salt solution method are considered useful for training in skin flap techniques.

Thiel embalming in neonates: methodology and benefits in medical training

Current teaching and training methods for surgical techniques in the pediatric population involve artificial models (manikins), animals or adult human cadavers embalmed using various techniques. We found no references in the literature concerning the use of the Thiel method in the pediatric population. The aim of this study, therefore, was to assess the viability of using pediatric human cadavers embalmed through Thiel’s technique and to compare them with standard pediatric manikins. After donation of a 24-week stillborn, the Thiel technique was carried out for fixation following the usual protocol. A video recording with eye-tracking glasses was used to perform an examination, and techniques. The same procedures were conducted on a pediatric manikin. Medical students, medical residents and physicians were asked to respond to questions in an online survey after being shown the video. A total of 92 responses were obtained. The Thiel-embalmed stillborn was assessed as superior to the manikin in all items. Our study confirmed that this technique is feasible even with extremely small donors. The value of this form of preservation for medical training is not widely known though it is receiving increasing interest. Our results show that Thiel fixation in pediatrics is clearly more highly valued than a manikin and offers great potential. This innovative application of the Thiel method in the pediatric population is technically possible. It poses no additional difficulties and is very positively assessed for undergraduate and postgraduate teaching.

Chemical Components of Smoke Produced From Versatile Training Tissue Models Using Electrocautery

INTRODUCTION

While exposure of surgeons and other staff to surgical smoke is an increasing health risk concern, there is a similar risk for users in surgical simulation and training. This study was undertaken to determine the chemical composition of smoke produced from a novel training model, Versatile Training Tissue (VTT), which is used for surgical simulation and training, and to compare this with smoke from a chemosynthetic model and porcine muscle and liver.

METHODS

A variety of models (VTT, polyvinyl alcohol, porcine muscle and liver) were prepared and cauterized. Identification of chemical substances in smoke was performed using gas chromatography-mass spectrometry. Quantitative instrumental analysis was implemented with gas chromatography-mass spectrometry and high-performance liquid chromatography. A convenient analysis was performed with a general smoke tube kit.

RESULTS

The main chemical components of smoke produced from VTT models include water and carbon dioxide. A small number of organic compounds were detected. Versatile Training Tissue models produced smoke with fewer compounds than smoke from a chemosynthetic model or porcine muscle.

CONCLUSIONS

The concentration of organic compounds from VTT models is considered to be below relevant health risk limits and lower than from polyvinyl alcohol and porcine muscle models. Although porcine liver smoke contains less of the main organic compounds of concern than a KM, it contains potentially hazardous nitrile compounds that are absent in KM smoke. Therefore, surgical simulation and training with VTT models should be considered relatively safe for trainees.

The Unintentional Effects on Body Donation Programs of a Competency-Based Curriculum in Postgraduate Medical Education

As medical programs place increasing importance on competency-based training and surgical simulations for residents, anatomy laboratories, and body donation programs find themselves in a position of adapting to changing demands. To better assess the demand for "life-like" cadaveric specimens and evaluate the possible impacts that competency-based medical education could have upon the body donation program of McGill University, Canada, the authors tracked, over the course of the last 10 years, the number of soft-embalmed specimens, along with the number of teaching sessions and the residents enrolled in competency-based programs that are using cadaveric material. The results reveal that the number of soft-embalmed specimens used within residency training increased from 5 in 2009 to 35 in 2019, representing an increase from 6% of bodies to 36.5% of the total number of body donors embalmed in this institution. Correspondingly, the number of annual teaching sessions for residents increased from 19 in 2012 to 116 in 2019. These increases in teaching are correlated with increasing number of residents enrolled in competency-based programs over the last 3 years (Pearson r ranging from 0.9705 to 0.9903, and R² ranging from 0.9418 to 0.9808). Those results suggest that the new skill-centered curricula which require residents to perform specific tasks within realistic settings, exhibit a growing demand for "life-like" cadaveric specimens. Institutions' body donation programs must, therefore, adapt to those greater need for cadaveric specimens, which presents many challenges, ranging from the logistical to the ethical.

Qualitative and quantitative comparison of Thiel and phenol-based soft-embalmed cadavers for surgery training

INTRODUCTION

Surgical skills training has traditionally been limited to formalin embalming that does not provide a realistic model. The aim of this study was to qualitatively and quantitatively compare Thiel and phenol-based soft-embalming techniques: qualitatively in a surgical training setup, and quantitatively by comparing the mechanical and histomorphometric properties of skin specimens embalmed using each method.

MATERIALS AND METHODS

Thirty-four participants were involved in surgical workshops comparing Thiel and phenol-based embalmed bodies. Participants were asked to evaluate the utility of the different models for surgical skills training. In parallel, tensile elasticity evaluation was performed on skin flaps from six fresh-frozen cadavers. Flaps were divided into three groups for each specimen: fresh-frozen, Thiel, and phenol-based embalmed and compared together at 1 month or 1 year after embalming. A histological investigation of the skin structural properties was performed for each embalming type using haematoxylin and eosin and Masson's trichrome.

RESULTS

All participants rated the phenol-based specimens consistently better or equivalent to Thiel for the evaluated parameters. Quantitatively, there were statistically significant differences for the tensile elasticity between the embalming techniques (p < .05). There were no significant differences for the tensile elasticity between phenol-based embalmed skin and fresh state (p = .30), and no significant difference between embalming time was reported (p = .47). Histologically, the integrity of the skin was better preserved with the phenol-based technique.

CONCLUSION

Phenol-based embalming provides as realistic or better of a model as Thiel embalming for surgical training skills and was generally preferred over Thiel model. The phenol-based embalming better preserved the integrity of the skin.

High-Fidelity Microsurgical Simulation: The Thiel Cadaveric Nerve Model and Evaluation Instrument

With surgical education moving from a time-based to a competency-based model, developing high-fidelity simulation models has become a priority. The Thiel cadaveric model has previously been used for a number of medical and surgical simulations, including microvascular simulation. We aim to investigate the use of the Thiel model in peripheral nerve simulation and validate a novel evaluation instrument. Sixteen residents ranging from postgraduate years 1 to 6 participated in the study. Their nerve coaptations using Thiel cadaveric nerves were video recorded and evaluated by 5 fellowship-trained microsurgeons using the Micro-Neurorrhaphy Evaluation Scale (MNES). The intraclass correlation among the 5 evaluators was 0.75, revealing excellent interrater reliability. The Cronbach α was .77, underlining the internal consistency of the test items. Bivariate analysis revealed a significant association between the MNES scores and the participants' self-declared level of experience. This correlation was confirmed by mixed modeling. Our results validate the MNES and underscore the utility of the Thiel nerve tissue for peripheral nerve surgical simulation.

Development of cadaver perfusion models for surgical training: an experimental study

PURPOSE

Perfusion techniques on cadavers are heterogeneous and imperfect. The objective of this study was to improve the existing circulation model for surgical simulation on cadavers.

METHODS

We used a three-step experimental approach. The first part of the experiment tested two variables: the type of circuit and the use of a heater for perfusion. The second approach evaluated two parameters: the injection fluid and the type of body conditioning (embalmed or freshly dead prepared using different washing techniques). The third one was an improvement on the best circulation obtained, which focused on the injection fluid. To compare the realism of these different techniques, we constructed a score with realism parameters: the volume of return flow, the presence of peripheral venous return and the perfusion of abdominal arteries.

RESULTS

We found that the use of a heater seemed to improve the perfusion, while performing an arteriovenous bypass did not seem very effective. A correlation rate of 0.84 was found between the realism score and the injected fluid chosen. The best score (4/6) was found for a non-embalmed body with a low-pressure washing technique using a gelatin-based liquid at a concentration of 4 g/L for circulation. Scores obtained using embalmed bodies for both injection fluids for high-pressure washing or for 8-g/L gelatin injection fluid did not exceed 3/6.

CONCLUSIONS

We showed that using a non-embalmed body with low-pressure washing and a 4-g/L gelatin-based fluid was the most effective technique for cadaver perfusion.

Techniques of cadaver perfusion for surgical training: a systematic review

PURPOSE

The objective of this study was to identify the most appropriate cadaver perfusion techniques for surgical training through a systematic review with a description of the protocols used.

METHODS

The search strategy included PubMed and reference tracking. Studies were identified by searching the electronic Medline databases. The search concepts included perfusion, cadavers and simulation training, and the protocol used is reported. This resulted in a qualitative review of 12 articles out of 250 articles consulted. We collected all the important data from these 12 articles.

RESULTS

Regarding the characteristics of the studies and the declotting or perfusion techniques, the results were heterogeneous. Indeed, in several studies, a good deal of information was unclear or insufficiently precise, making it unfeasible to summarize the data. The methods used were not sufficiently explicit and detailed. However, a majority of the fresh cadavers used tap water for declotting. Perfusion, type of fluid, number of pumps, pressure, pulsatility, and arterial or venous approaches differed greatly. Only two studies fulfilled five of our six realism criteria for surgical simulation.

CONCLUSIONS

This systematic review provided an overview of all the different cadaver perfusion techniques. It could be used to establish a reference method of a simulation model.

Learning anatomy through Thiel- vs. formalin-embalmed cadavers: Student perceptions of embalming methods and effect on functional anatomy knowledge

Thiel-embalmed cadavers, which have been adopted for use in anatomy teaching in relatively few universities, show greater flexibility and color retention compared to formalin-embalmed cadavers, properties which might be considered advantageous for anatomy teaching. This study aimed to investigate student attitudes toward the dissection experience with Thiel- compared to formalin/ethanol-embalmed cadavers. It also aimed to determine if one embalming method is more advantageous in terms of learning functional anatomy through the comparison of student anterior forearm functional anatomy knowledge. Student opinions and functional anatomy knowledge were obtained through use of a questionnaire from students at two medical schools, one using Thiel-, and one using more traditional formalin/ethanol-embalmed cadavers. Both the Thiel group and the formalin group of students were surveyed shortly after completing an anterior forearm dissection session. Significant differences (P-values <0.01) in some attitudes were found toward the dissection experience between cohorts using Thiel- vs. formalin-embalmed cadavers. The Thiel group of students felt more confident about recognizing anatomy in the living individual, found it easier to identify and dissect anatomical structures, and indicated more active exploration of functional anatomy due to the retained flexibility of the cadaver. However, on testing, no significant difference in functional anatomy knowledge was found between the two cohorts. Overall, although Thiel embalming may provide an advantageous learning experience in some investigated areas, more research needs to be carried out, especially to establish whether student perception is based on reality, at least in terms of structure identification. Anat Sci Educ 11: 166-174. © 2017 American Association of Anatomists.

Cadaveric simulation: a review of reviews

BACKGROUND

Traditional surgical training, largely based on the Halstedian model "see one, do one, teach one" is not as effective in the era of working time restrictions and elaborate shift-patterns. As a result, contemporary surgeons turned to educational methods outside the operating theatre such as simulation. Cadavers are high fidelity models but their use has ethical and cost implications and their availability may be limited. In this review, we explore the role of cadaveric simulation in modern surgical education.

METHODS

All the Evidence-Based Medicine databases were searched for relevant reviews. The resulting studies were assessed for inclusion to this review, according to pre-determined criteria. Data extraction was performed using a custom-made spreadsheet, and the quality of included reviews was assessed using a validated scoring system (AMSTAR).

RESULTS

The literature review yielded 33 systematic reviews; five of which matched the inclusion criteria and were included in this review of reviews. Cadaveric simulation was found to have good face (subjective assessment of usefulness) and content validity (whether a specific element adds or retracts to the educational value) while trainees improved their surgical skills after practicing on cadavers. However, concerns have been raised about ethical issues, high cost and availability.

CONCLUSION

Cadavers are an effective medium for surgical teaching, and it may be appropriate for them to be used whenever surrounding conditions such cost and availability allow. Further research is required to provide evidence on whether there is equivalence between cadavers and other educational media which may not bear the same shortcomings.

A Multispecialty Evaluation of Thiel Cadavers for Surgical Training

Background

Changes in UK legislation allow for surgical procedures to be performed on cadavers. The aim of this study was to assess Thiel cadavers as high-fidelity simulators and to examine their suitability for surgical training.

Methods

Surgeons from various specialties were invited to attend a 1 day dissection workshop using Thiel cadavers. The surgeons completed a baseline questionnaire on cadaveric simulation. At the end of the workshop, they completed a similar questionnaire based on their experience with Thiel cadavers. Comparing the answers in the pre- and post-workshop questionnaires assessed whether using Thiel cadavers had changed the surgeons’ opinions of cadaveric simulation.

Results

According to the 27 participants, simulation is important for surgical training and a full-procedure model is beneficial for all levels of training. Currently, there is dissatisfaction with existing models and a need for high-fidelity alternatives. After the workshop, surgeons concluded that Thiel cadavers are suitable for surgical simulation (p = 0.015). Thiel were found to be realistic (p < 0.001) to have reduced odour (p = 0.002) and be more cost-effective (p = 0.003). Ethical constraints were considered to be small.

Conclusion

Thiel cadavers are suitable for training in most surgical specialties.

Cadaveric Spinal Surgery Simulation: A Comparison of Cadaver Types

Study Design Single-blinded study. Objective To assess the suitability of three types of cadaver for simulating pedicle screw insertion and establish if there is an ideal. Methods Three types of cadaver-Thiel-embalmed, Crosado-embalmed, and formaldehyde-embalmed-were draped and the spines exposed. Experienced surgeons were asked to place pedicle screws in each cadaver and give written questionnaire feedback using a modified Likert scale. Soft tissue and bony properties were assessed, along with the role of simulation in spinal surgery training. Results The Thiel cadaver rated highest for soft tissue feel and appearance with a median score of 6 for both (range 2 to 7). The Crosado cadaver rated highest for bony feel, with a median score of 6 (range 2 to 7). The formaldehyde cadaver rated lowest for all categories with median scores of 2, 2.5, and 3.5, respectively. All surgeons felt pedicle screw insertion should be learned in a simulated setting using human cadavers. Conclusion Thiel and Crosado cadavers both offered lifelike simulation of pedicle screw insertion, with each having advantages depending on whether the focus is on soft tissue approach or technical aspects of bony screw insertion. Both cadaver types offer the advantage of long life span, unlike fresh frozen tissue, which means cadavers can be used multiple times, thus reducing the costs.

History and future of human cadaver preservation for surgical training: from formalin to saturated salt solution method

Traditionally, surgical training meant on-the-job training with live patients in an operating room. However, due to advancing surgical techniques, such as minimally invasive surgery, and increasing safety demands during procedures, human cadavers have been used for surgical training. When considering the use of human cadavers for surgical training, one of the most important factors is their preservation. In this review, we summarize four preservation methods: fresh-frozen cadaver, formalin, Thiel's, and saturated salt solution methods. Fresh-frozen cadaver is currently the model that is closest to reality, but it also presents myriad problems, including the requirement of freezers for storage, limited work time because of rapid putrefaction, and risk of infection. Formalin is still used ubiquitously due to its low cost and wide availability, but it is not ideal because formaldehyde has an adverse health effect and formalin-embalmed cadavers do not exhibit many of the qualities of living organs. Thiel's method results in soft and flexible cadavers with almost natural colors, and Thiel-embalmed cadavers have been appraised widely in various medical disciplines. However, Thiel's method is relatively expensive and technically complicated. In addition, Thiel-embalmed cadavers have a limited dissection time. The saturated salt solution method is simple, carries a low risk of infection, and is relatively low cost. Although more research is needed, this method seems to be sufficiently useful for surgical training and has noteworthy features that expand the capability of clinical training. The saturated salt solution method will contribute to a wider use of cadavers for surgical training.

From "silent teachers" to models

In this essay Roos Eisma and Tracey Wilkinson describe how the Thiel technique has expanded the range of applications in which embalmed human cadavers can be used.

For decades, embalmed cadavers have played an important role in teaching anatomy to the scientists and doctors of the future. Most anatomy departments use a traditional formaldehyde-based embalming method, but formalin embalming makes the bodies very rigid, which limits their usefulness for procedures other than dissection. A more recent embalming method developed by W. Thiel has allowed these “silent teachers” to take on a further role in applied anatomy research and teaching: to act as models for surgical training and medical research.