Saturated Salt Solution Cadaver-Embalming Method Improves Orthopaedic Surgical Skills Training

Gross, organoleptic and histologic assessment of cadaveric equine heads preserved using chemical methods for veterinary surgical teaching

BACKGROUND

Preservation of biological tissues has been used since ancient times. Regardless of the method employed, tissue preservation is thought to be a vital step in veterinary surgery teaching and learning.

OBJECTIVES

This study was designed to determine the usability of chemically preserved cadaveric equine heads for surgical teaching in veterinary medicine.

METHODS

Six cadaveric equine heads were collected immediately after death or euthanasia and frozen until fixation. Fixation was achieved by using a hypertonic solution consisting of sodium chloride, sodium nitrite and sodium nitrate, and an alcoholic solution containing ethanol and glycerin. Chemically preserved specimens were stored at low temperatures (2°C to 6°C) in a conventional refrigerator. The specimens were submitted to gross and organoleptic assessment right after fixative solution injection (D0) and within 10, 20, and 30 days of fixation (D10, D20, and D30, respectively). Samples of tissue from skin, tongue, oral vestibule, and masseter muscle were collected for histological evaluation at the same time points.

RESULTS

Physical and organoleptic assessments revealed excellent specimen quality (mean scores higher than 4 on a 5-point scale) in most cases. In some specimens, lower scores (3) were assigned to the range of mouth opening, particularly on D0 and D10. A reduced the range of mouth opening may be a limiting factor in teaching activities involving structures located in the oral cavity.

CONCLUSIONS

The excellent physical, histologic, and organoleptic characteristics of the specimens in this sample support their usability in teaching within the time frame considered. Appropriate physical and organoleptic characteristics (color, texture, odor, and flexibility) of the specimens in this study support the use of the method described for preparation of reusable anatomical specimens.

An objective assessment for bone drilling: A pilot study on vertical drilling

The purpose of this study is to propose a quantitative assessment scheme to help with surgical bone drilling training. This pilot study gathered and compared motion and force data from expert surgeons (n = 3) and novice residents (n = 6). The experiment used three-dimensional printed bone simulants of young bone (YB) and osteoporotic bone (OB), and drilling overshoot, time, and force were measured. There was no statistically significant difference in overshoot between the two groups (p = 0.217 for YB and 0.215 for OB). The results, however, show that the experts took less time (mean = 4.01 s) than the novices (mean = 9.98 s), with a statistical difference (p = 0.003 for YB and 0.0001 for OB). In addition, the expert group performed more consistently than the novices. The force analysis further revealed that experts used a higher force to drill the first cortical section and a noticeably lower force in the second cortex to control the overshoot (approximate reduction of 5.5 N). Finally, when drilling time and overshoot distance were combined, the motion data distinguished the skill gap between expert and novice drilling; the force data provided insight into the drilling mechanism and performance outcomes. This study lays the groundwork for a data-driven training scheme to prepare novice residents for clinical practice.

Updates on cadaver surgical training in Japan: a systematic facility at Chiba University

Cadaver surgical training (CST), which ensures medical safety by improving the skills of surgeons, is popular overseas. However, training involves ethical issues given the use of cadavers. In 2012, the Japan Surgical Society and the Japanese Association of Anatomists compiled and opened the “Guidelines for Cadaver Dissection in Education and Research of Clinical Medicine (Guideline 2012)” to the public. This has allowed Japan to conduct CST or research under the regulations of Postmortem Examination and Corpse Preservation Act and the Body Donation Act. However, its dissemination has been sluggish. The Clinical Anatomy Lab (CAL), established in 2010 at Chiba University, is a facility for conducting CST and research. In the 11 years since its inception, 250 programs have been implemented. Orthopedics had the most implemented in the clinical field, with 120 (48%), followed by emergency and critical care medicine with 27 (10.8%), and neurological surgery with 27 (10. 8%). Based on the purpose of the training, the most common objective for the programs (approximately 83%) was education. Further, the highest number of programs was recorded in 2018 (34) and participants in 2017 (631). The implementation of CST requires more than just guiding surgeons to a dissection practice room. There are several methods of preserving cadavers to make them suitable for CST. For various surgical simulations, an operating table is more suitable than a dissection table. The current paper provides information on how to implement CST in universities that have so far only worked on anatomy education for medical students.

Swine viscera preservation in hypersaturated salt solution after alcohol fixation as a preparation method for educational purposes

The use of live animals for educational purposes is an old practice that is still employed in teaching and research institutions. However, there are several objections to this practice, whether for ethical or humanitarian reasons. Surgical techniques teaching using anatomical pieces and/or preserved cadavers promotes greater learning efficiency, provides exercise repetition and increases the confidence and satisfaction of the students when compared to the use of live animals. The current work aimed to analyse the feasibility of using fresh swine urinary bladder and small intestines (jejunum), obtained from slaughterhouses, fixed in 99.8% ethyl alcohol (EA) and preserved in sodium chloride hypersaturated solution (SCHS) at 30%, for 7, 14 and 21 days, as an alternative method for surgical skills training (SST). Swine viscera, fixed in EA and preserved in SCHS, presented a realistic appearance, absence of odour and maintained the viable morphological characteristics during the performance of the operative techniques. Preservation solutions had low cost, were easy to acquire and did not offers risks to human health. Therefore, urinary bladders and small intestines fixed in 99.8% EA for 30 days and maintained in 30% SCHS at different periods were demonstrated as a good viable option as a preservation method for surgical skills training.

Biomechanical models: key considerations in study design

This manuscript summarizes presentations of a symposium on key considerations in design of biomechanical models at the 2019 Basic Science Focus Forum of the Orthopaedic Trauma Association. The first section outlines the most important characteristics of a high-quality biomechanical study. The second section considers choices associated with designing experiments using finite element modeling versus synthetic bones versus human specimens. The third section discusses appropriate selection of experimental protocols and finite element analyses. The fourth section considers the pros and cons of use of biomechanical research for implant design. Finally, the fifth section examines how results from biomechanical studies can be used when clinical evidence is lacking or contradictory. When taken together, these presentations emphasize the critical importance of biomechanical research and the need to carefully consider and optimize models when designing a biomechanical study.

The Usefulness of Saturated Salt Solution Embalming Method for Oral Surgical Skills Training: A New Cadaveric Training Model for Bone Harvesting

The purpose of this study was to assess the usefulness of saturated salt solution-embalmed cadavers for oral surgical skills training related to bone graft harvesting. Two half-day surgical skills training workshops were held at the Tokyo Medical University utilizing eight cadavers embalmed with the saturated salt solution. A total of 22 participants including oral surgeons, residents, and dentists attended the workshop. Surgical training consisted of six procedures related to intraoral and extraoral bone harvesting. The participants were surveyed to assess self-confidence levels for each surgical procedure before and after completion of each workshop. The Wilcoxon signed-rank test was used to compare the differences between each median score before and after the workshop. There were statistically significant increases in the self-assessed confidence scores in bone harvesting procedures for the zygomatic bone (P = 0.003), maxillary tuberosity (P = 0.002), and other sites (P < 0.001). The anatomical features of saturated salt solution-embalmed cadavers were also examined. The textures of the oral mucosa and skin were similar to those of living individuals. The structure of bone tissues was well-preserved and the hardness was realistic. Consequently, all procedures were performed with sufficient realism. The saturated salt solution method has a relatively low cost of preparation and storage, and almost no odor. The authors suggest that saturated salt solution-embalmed cadavers could provide a new model for oral surgical skills training in bone harvesting.

Toward safer thanatopraxy cares: formaldehyde-releasers use

Human cadavers constitute very useful educational tools to teach anatomy in medical scholarship and related disciplines such as physiology, for example. However, as biological material, human body is subjected to decay. Thanatopraxy cares such as embalming have been developed to slow down and inhibit this decay, but the formula used for the preservation fluids are mainly formaldehyde (FA)-based. Very recently, other formulas were developed in order to replace FA, and to avoid its toxicity leading to important environmental and professional exposure concerns. However, these alternative FA-free fluids are still not validated or commercialized, and their efficiency is still under discussion. In this context, the use of FA-releasing substances, already used in the cosmetics industry, may offer interesting alternatives in order to reduce professional exposures to FA. Simultaneously, the preservation of the body is still guaranteed by FA generated over time from FA-releasers. The aim of this review is to revaluate the use of FA in thanatopraxy cares, to present its benefits and disadvantages, and finally to propose an alternative to reduce FA professional exposure during thanatopraxy cares thanks to FA-releasers use.

Advanced cadaver-based educational seminar for trauma surgery using saturated salt solution-embalmed cadavers

Aim

Senior surgeons in Japan who participated in "cadaver-based educational seminar for trauma surgery (CESTS)" subsequently stated their interest in seminars for more difficult procedures. Therefore, we held a 1-day advanced-CESTS with saturated salt solution (SSS)-embalmed cadavers and assessed its effectiveness for surgical skills training (SST).

Methods

Data were collected from three seminars carried out from September 2015 to January 2018, including a 10-point self-assessment of confidence levels (SACL) questionnaire on nine advanced surgical skills, and evaluation of seminar content before, just after, and half a year after the seminar. Participants assessed the suitability of the two embalming methods (formalin solution [FAS] and SSS) for SST, just after the seminar. Statistical analysis resulted in P < 0.0167 comparing SACL results from seminar evaluations at the three time points and P < 0.05 comparing FAS to SSS.

Results

Forty-three participants carried out surgical procedures of the lung, liver, abdominal aorta, and pelvis and extremity. The SACL scores increased in all skills between before and just after the seminar, but were decreased by half a year after. However, SACL scores of each skill did not change significantly, except for external fixation for pelvic fracture at just after and half a year after. The SSS-embalmed cadavers were evaluated as being more suitable than FAS-embalmed cadavers for each procedure.

Conclusions

Advanced-CESTS using SSS-embalmed cadavers increased the participants' self-confidence just after the seminar, which was maintained after half a year in each skill, except external fixation for pelvic fracture. Therefore, SSS-embalmed cadavers are useful for SST, particularly for surgical repairs.

Feasibility of total en-bloc spondylectomy on L5 by a posterior-only approach: An autopsy study

Purpose

To obtain a better understanding of the structures around L5 vertebra and provide some anatomical evidence of the feasibility of total en-bloc spondylectomy (TES) on L5 in a posterior-only approach.

Methods

12 simulated TESs on L5 by a posterior-only approach were conducted on human cadavers. The distance between the traction point of L4 nerve root and the dural sac (Da), the anterior-posterior diameter of the vertebral body,(Va), the distance between the start point of L4 nerve root and the traction point of L5 nerve root (Dh) and the height of the vertebral body (Vh) were measured. Paired t-test and liner regression were performed to determine the difference and correlation between Da and Va, and between Dh and Vh. The risk of nerve roots or blood vessels damages, and the obstruction caused by iliac wings were evaluated.

Results

Liner correlations were found between Da and Va, and between Dh and Vh. The regression equations were Da = 0.6673Va + 11.28 and Dh = 1.009Vh + 1.003. There are statistical significant differences between Dh and Vh, and between Da and Va in those whose Va < 34.96 mm. Nerve roots or blood vessels damages and the obstruction caused by iliac wing were able to be avoided.

Conclusions

If the patient has an anterior-posterior diameter of L5 vertebral body shorter than 34.96 mm, it is possible that the vertebral body can be taken out during TES in a posterior-only approach. Prevention of nerve roots or blood vessels damages, and the obstruction caused by iliac wings are difficulties of this procedure yet not insurmountable. TES on L5 by a posterior-only approach might a possible alternative in treating diseases like L5 vertebral body tumors.