Anatomy is a valuable teaching tool. Dissection of human cadavers remains at the heart of the teaching of anatomy at the Center for Anatomy and Human Identification. (6) Like any practical skill, practice is essential to learning surgery. The ability of surgeons to have technical experience on a dead body before surgery on a live patient allows surgeons to understand the anatomy, minimize possible damage and try the procedure before actually experimenting. (1) Until 2006, it was illegal in the UK to practice surgery on corpses.
This means that surgeons have to exercise their skills in synthetic models or animal carcasses such as cats, dogs, rabbits, and pigs. Frozen body parts are also used, but carry a high degree of risk of infection and disintegration in a day or two. Prior to 2006, cadavers could have been used for dissection but not surgery, out of respect for the deceased. The use of animals is never perfect because dissection is not always a good match for the human body.
Recent changes in the Human Tissue Act (England, Wales and Northern Ireland) and the Anatomy Act (Scotland) now allow for surgical operations on human cadavers within the United Kingdom. At the same time, the European Working Time Directive (EWTD) has reduced the amount of time that trained surgeons can spend in the operating room and thus have the opportunity to train. (6) The use of human corpses as a tool for learning and teaching is restricted normally by decomposition. In an educational environment where dissection lessons are spread throughout the academic year, cadaver preservation is necessary to provide ideal learning conditions and to facilitate the effective use of this limited and valuable resource.
The preservation for anatomical purposes is successful when reducing the risk of infection, preventing decomposition, tissue softness, muscle and organs color similar to unpreserved subjects closely. (3) The first evidence of intentional embalming of human remains was documented during the first family in Egypt around 2640 B.C. Later, the practice of embalming was adopted in Europe, where advances in the techniques of embalming accompanied medical developments. (3)
Embalming by injection of the blood vessels was first during the Renaissance period, and reports on the effective use of arterial formaldehyde injection that was followed during the early 20th century. Formaldehyde has been an essential component of embalming solutions since then. (3) With regard to medical education in the United Kingdom, formalin is currently the most widely used embalming solution for the long-term preservation of cadavers, but many restrictions have been reported regarding this embalming method. The chemical is known to affect water and tissue color negatively, it has a total rigid feeling and is associated with a penetrating odor. (3) Potential health risks associated with formalin embalming have been investigated in medical students with short-term exposure to formaldehyde found to provoke headache, skin irritation and mucous membranes. Is classified as a carcinogen, and occupational exposure is likely to have long-term health effects. H€olzle et al. (2012) also suggested that samples containing formalin are not suitable for the reliable practice of surgical procedures because of the many limitations associated with them. (3)
‘A formaldehyde-preserved body is not like a real body,’ says Dr Lena Vogt, a foot surgeon from Germany. ‘It starts with the skin. You just touch it lightly with the scalpel and it falls apart.’ She says that the objects lack colour and the layers of tissue stick together making it ‘difficult to decide if [it] is a nerve, an artery or a vein.’ (1) Mohamed, (2012) reported that due to its toxicity and its use, which leads to increased stiffness of cadaver and tissue darkening, makes it difficult to perform dissection and the practice of surgical techniques on the cadaver. Therefore, in addition to the need to maintain bodies with characteristics that approximate the fresh cadaver as much as possible, large research has been devoted to searching for the correct solution to reduce and/or replace the use of formaldehyde. (5) Among these solutions, (5 ) Thiel (1992, 2002), developed over several decades, is the so-called Thiel soft-fix embalming method (1), a less dangerous and widely applicable method of preserving corpses. Harmful substances, such as formaldehyde, are present in small concentrations; 8.9% of formaldehyde solution is used, with final Thiel solutions containing 1.44% (arterial infusion), 2.43% (venous infusion) and 0.65% (tank fluid) instead of the more standard 37–40% formaldehyde concentration used in formalin embalming, with a final formalin solution of 5% or less being adequate. (3)
Mohammed said (2012) that this method of dealing with the cadaver is more efficient and comfortable, and lacks toxic or irritating gases because of the minimum formaldehyde concentrations used in the formula. (5) Microbiological tests also demonstrated excellent biocidal properties (Thiel, 1992a). (6) Mohammad (2012) stated that the cancer risks of Thiel embalming fluid are generally considered minimal, and this method shows greater flexibility and retention of color than formalin-embalmed cadavers, properties which can be considered useful for teaching of anatomy. Mohammed also noted that the Thiel group of students was more confident in recognizing anatomy in the living individual and found it easier to identify and dissect the anatomical structures, and suggested a more active exploration of functional anatomy because of the flexibility in cadaver retention. (3) However, the Thiel embalming fluid contains flammable compounds, as well as boric acid and ethanol, both apparently dedicated to the phase-out of embalming solutions by the European Union (EU). (3) In addition, Brenner (2014) described the Thiel method as more expensive than other embalming methods; other authors estimated the cost of embalming a cadaver at ten times or 20 times the cost of a formalin cadaver. Some of these additional costs are related to the need to install large tanks for the immersion step in the embalming process.
Other limitations associated with Thiel-embalmed samples as discussed in the literature. Benkhadra et al. (2011) discussed the loss of muscle fiber integrity, while Healy et al. (2015) showed that the availability of relatively few trained experts on this embalming technique, the relatively high costs associated with it, and the long time to prepare up to six months could be considered a defect by institutions considering investing in this method. Fessel et al. (2011) found that Thiel samples are not suitable for biomechanical testing, where increased tendon flexibility was observed after the embalming process. Healy et al. (2015) were also observed occasional mummification of the distal limbs and the structures of the central nervous system are not preserved well (Hammer et al., 2015). Also, 14 surgeons assessed embalming using Thiel, saturated salt and formalin solution methods in a study by Hayashi et al. (2014) noted that some areas of the embalmed body, such as the heart and kidneys, were considered too soft to practice surgeries. (3) Thiel-embalmed cadavers, despite their limitations, are described as exceptionally lifelike (Groscurth et al., 2001), with a realistic representation of structures (Prasad Ray et al., 2012; Hammer et al., 2015; Ray et al., 2015) almost equivalent to clinical conditions (Wolff et al., 2008).
This is due to the preservation of soft tissue consistency (Fessel et al., 2011), high mobility of the joints (Eisma and Wilkinson, 2014; Hayashi et al., 2014); preservation of tissue color compared to unembalmed or formalin samples (Jaung et al. , 2011), and a total supply and flexibility of appearance (Benkhadra et al., 2011). Because of this flexibility and softness, it is reported that Thiel embalming has a positive effect on the dissection experience of the musculoskeletal system (Balta et al., 2015), indicating its applicability for both identification and estimation of anatomical structures by dissection, and active exploration of shape and function of the human body by manipulation of structures. In addition, Hayashi et al. (2014) found that ultrasound images of Thiel-embalmed cadavers were clear, unlike cadavers of formalin, and that there was no accumulation of fluids, as shown in cadavers embalmed with the saturated salt solution. These results have positive effects on the application of Thiel-embalmed samples in surgical training. (3) Soft mummification is a technique based on a combination of salt compounds and very low amounts of volatile formaldehyde and formalin for fixation, 4 boric acid for disinfection, and ethylene glycol to maintain tissue plasticity (Thiel, 1992; 2002).
(5) The cadavers are perfused via the femoral or carotid artery with an intravascular solution containing 14,300 ml of solution A, 500 ml of solution B, 700 g of sodium sulfite and 300 ml formalin for a body weighing 80 kg. (5) Muhammad (2012) states that there are A number of other soft-fix embalming methods are available both inside and outside the United Kingdom (Coleman and Kogan, 1998; Anderson, 2006; Silva et al., 2007; Barton et al., 2009; Al-Hayani et al., 2011; Jaung et al., 2011). Our interest in Thiel was based on long-term preservation without the need for cooling, excellent flexibility and tissue quality compared to other options. (6) In 2009, the Center for Anatomy and Human Identity at the University of Dundee began Thiel embalming on a small scale to assess the suitability of current teaching in which long‐lasting dissection courses are basic, the potential for new collaborations and activities, and the practical implications of changing mummification method from formalin to Thiel. (6) They reported that their experiments with dissection were mostly positive and especially for teaching the musculoskeletal system. Internal organs deal differently from formalin‐fixed organs and dissection manuals must be set to reflect this. (6) It can also be used in imaging studies, where X-ray, CT, MRI, and ultrasound provide a very realistic experience.
Dundee University is the first British institution to adopt this method, and has several years of experience working with it, and is now the leading Thiel facility in the UK. Technicians have been consulted by a variety of anatomical institutions around the world already, including Sri Lanka, Israel, Thailand, and the United Kingdom. (2) Since this technique is described in German, it is not particularly known, (4) and hardly used outside German-speaking countries according to a recent survey (Benkhadra et al., 2011); lack of knowledge about practical details was cited as one of the reasons for its non-use. (6)
Its multiple uses are applicable in the teaching of anatomy and research. Teaching for undergraduates (prosection and dissection) and training in surgical techniques for graduates and specialists (laparoscopies, arthroscopies, endoscopies). (5) Thiel‐embalmed cadavers were found to provide a unique opportunity to evaluate medical products, especially in areas where there is no suitable alternative model, and no complications associated with clinical trials. (6) Cadavers were also used in biomechanical studies (Boryor et al., 2010) and the training of surgeons and anesthesiologists who perform image-guided procedures and dentists (Groscurth et al., 2001; Giger et al., 2008; Wolff et al., 2008; Benkhadra et (Holzle et al., 2009; McLeod et al., 2010; Eisma et al., 2011). (6)
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