On the suitability of Thiel‐fixed samples for biomechanical purposes: Critical considerations on the articles of Liao et al. “elastic properties of Thiel‐embalmed human ankle tendon and ligament” and Verstraete et al. “impact of drying and thiel embalming on mechanical properties of achilles tendons”

Hammer, Niels; Schröder, Christian; Schleifenbaum, Stefan

doi:10.1002/ca.22679

Cited by 9 publications

(9 citation statements)

References 8 publications

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“…The PE‐based fixation may be considered well suited for undergraduate teaching and partly suited for postgraduate education. The use of PE‐based tissues for biomechanical experiments should be limited to pilot trials on bones and ligaments, with unembalmed fresh tissues giving clearly superior results (Scholze et al, 2018; Lozano et al, 2019) as even small quantities of ethanol and formaldehyde are known to impact negatively on the load‐deformation behavior of bone (Hammer et al, 2014; Trowbridge et al, 2017; Becker et al, 2019) and soft tissue (Steinke et al, 2012; Hammer et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Phenoxyethanol‐Based Embalming for Anatomy Teaching: An 18 Years' Experience with Crosado Embalming at the University of Otago in New Zealand

Crosado

Löffler

Ondruschka

et al. 2020

Anatomical Sciences Ed

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Embalming fixatives such as formaldehyde and phenol have been associated with occupational health hazards. While anatomists aim at replacing these chemicals, this seems presently unfeasible in particular for formaldehyde. Furthermore, fixation protocols usually require well-equipped facilities with highly experienced staff to achieve good fixation results in spite of only a minimal use of formaldehyde. Combining these aspects, a technique robust enough to be carried out by morticians is presented, resulting in durable tissues with minimal formaldehyde use. An embalming protocol involving phenoxyethanol was established, using concentrations of 7 and 1.5 Vol% of phenoxyethanol in the fixative and the conservation fluid, respectively. Visual, haptic, histological, and biomechanical properties and their perceived potential to positively influence student learning outcomes were compared to standard embalming techniques. The phenoxyethanol technique provides esthetic, durable, and odorless tissues. Bleaching is less pronounced compared to ethanol-or formaldehydebased protocols. The tissues remain pliable following the phenoxyethanol-based embalming and can be used for biomechanical experiments to some extent. Phenoxyethanol-fixed tissues are well suited for undergraduate teaching with perceived positive learning outcomes and partly for postgraduate training. Phenoxyethanol tissues provide the option to obtain well-preserved histology samples, similar to those derived from formaldehyde. The provided protocol helps replace the use of phenol and formaldehyde for conservation purposes and minimizes the use of formaldehyde for the initial injection fixation. Phenoxyethanol-based embalming forms an effective alternative to standard embalming techniques for human cadavers. It is simple to use, allowing fixation procedures to be carried out in less sophisticated facilities with non-anatomy staff. Anat Sci Educ 0: 1-16.

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Section: Discussionmentioning

confidence: 99%

Phenoxyethanol‐Based Embalming for Anatomy Teaching: An 18 Years' Experience with Crosado Embalming at the University of Otago in New Zealand

Crosado

Löffler

Ondruschka

et al. 2020

Anatomical Sciences Ed

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“…A chemical treatment of the soft tissues such as the use of fixatives for cadaveric preservation may alter the collagen interaction and hence the mechanical parameters of the respective tissue, which was shown for the human scalp, DM and temporal muscle fascia [ 18 , 30 , 31 ], or iliotibial tract specimens when fixed with ethanol or formaldehyde [ 24 ]. Formaldehyde as a component of the Thiel fixation is known to irreversibly block the amino groups of peptides and to cross-link hydroxymethylene bridges [ 32 , 33 ].…”

Section: Discussionmentioning

confidence: 99%

What Is Considered a Variation of Biomechanical Parameters in Tensile Tests of Collagen-Rich Human Soft Tissues?—Critical Considerations Using the Human Cranial Dura Mater as a Representative Morpho-Mechanic Model

et al. 2020

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Background and Objectives: Profound knowledge on the load-dependent behavior of human soft tissues is required for the development of suitable replacements as well as for realistic computer simulations. Regarding the former, e.g., the anisotropy of a particular biological tissue has to be represented with site- and direction-dependent particular mechanical values. Contrary to this concept of consistent mechanical properties of a defined soft tissue, mechanical parameters of soft tissues scatter considerably when being determined in tensile tests. In spite of numerous measures taken to standardize the mechanical testing of soft tissues, several setup- and tissue-related factors remain to influence the mechanical parameters of human soft tissues to a yet unknown extent. It is to date unclear if measurement extremes should be considered a variation or whether these data have to be deemed incorrect measurement outliers. This given study aimed to determine mechanical parameters of the human cranial dura mater as a model for human soft tissues using a highly standardized protocol and based on this, critically evaluate the definition for the term mechanical “variation” of human soft tissue. Materials and Methods: A total of 124 human dura mater samples with an age range of 3 weeks to 94 years were uniformly retrieved, osmotically adapted and mechanically tested using customized 3D-printed equipment in a quasi-static tensile testing setup. Scanning electron microscopy of 14 samples was conducted to relate the mechanical parameters to morphological features of the dura mater. Results: The here obtained mechanical parameters were scattered (elastic modulus = 46.06 MPa, interquartile range = 33.78 MPa; ultimate tensile strength = 5.56 MPa, interquartile range = 4.09 MPa; strain at maximum force = 16.58%, interquartile range = 4.81%). Scanning electron microscopy revealed a multi-layered nature of the dura mater with varying fiber directions between its outer and inner surface. Conclusions: It is concluded that mechanical parameters of soft tissues such as human dura mater are highly variable even if a highly standardized testing setup is involved. The tissue structure and composition appeared to be the main contributor to the scatter of the mechanical parameters. In consequence, mechanical variation of soft tissues can be defined as the extremes of a biomechanical parameter due to an uncontrollable change in tissue structure and/or the respective testing setup.

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“…Furthermore, it could be shown by others that the stress-strain and failure-load data were minutely affected by post mortem delay up to 96 hours in a rabbit model [ 30 ]. Nevertheless, the effects of water content, drying and fixation, as known from Thiel fixation, cannot completely excluded and thus limit the estimation of a realistic behavior [ 31 – 33 ].…”

Section: Discussionmentioning

confidence: 99%

“…However, it needs to be mentioned that our study has a number of limitations. By investigating exclusively elderly cadavers originating and in a very limited sample size [ 33 ] we are unable to determine the potential effects of aging, which are well known to alter the mechanical properties of the hip capsule [ 12 – 15 , 17 , 18 , 24 , 34 , 46 ]. We also did not use a polyaxial test setup, which would have been necessary to measure a wire-mesh-like collagen arrangement as presumably existent in the capsular ligaments of the hip joint [ 2 ].…”

Section: Discussionmentioning

confidence: 99%

The Stress-Strain Data of the Hip Capsule Ligaments Are Gender and Side Independent Suggesting a Smaller Contribution to Passive Stiffness

Pieroh

Schneider²,

Lingslebe³

et al. 2016

PLoS ONE

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BackgroundThe ligaments in coherence with the capsule of the hip joint are known to contribute to hip stability. Nevertheless, the contribution of the mechanical properties of the ligaments and gender- or side-specific differences are still not completely clear. To date, comparisons of the hip capsule ligaments to other tissues stabilizing the pelvis and hip joint, e.g. the iliotibial tract, were not performed.Materials & MethodsHip capsule ligaments were obtained from 17 human cadavers (9 females, 7 males, 13 left and 8 right sides, mean age 83.65 ± 10.54 years). 18 iliofemoral, 9 ischiofemoral and 17 pubofemoral ligaments were prepared. Uniaxial stress-strain properties were obtained from the load-deformation curves before the secant elastic modulus was computed. Strain, elastic modulus and cross sections were compared.ResultsStrain and elastic modulus revealed no significant differences between the iliofemoral (strain 129.8 ± 11.1%, elastic modulus 48.8 ± 21.4 N/mm2), ischiofemoral (strain 128.7 ± 13.7%, elastic modulus 37.5 ± 20.4 N/mm2) and pubofemoral (strain 133.2 ± 23.7%, elastic modulus 49.0 ± 32.1 N/mm2) ligaments. The iliofemoral ligament (53.5 ± 15.1 mm2) yielded a significantly higher cross section compared to the ischiofemoral (19.2 ± 13.2 mm2) and pubofemoral (15.2 ± 7.2 mm2) ligament. No significant gender- or side-specific differences were determined. A comparison to the published data on the iliotibial tract revealed lower elasticity and less variation in the ligaments of the hip joint.ConclusionComparison of the mechanical data of the hip joint ligaments indicates that their role may likely exceed a function as a mechanical stabilizer. Uniaxial testing of interwoven collagen fibers might lead to a misinterpretation of the mechanical properties of the hip capsule ligaments in the given setup, concealing its uniaxial properties. This underlines the need for a polyaxial test setup using fresh and non-embalmed tissues.

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Cited by 9 publications

References 8 publications

Phenoxyethanol‐Based Embalming for Anatomy Teaching: An 18 Years' Experience with Crosado Embalming at the University of Otago in New Zealand

Phenoxyethanol‐Based Embalming for Anatomy Teaching: An 18 Years' Experience with Crosado Embalming at the University of Otago in New Zealand

What Is Considered a Variation of Biomechanical Parameters in Tensile Tests of Collagen-Rich Human Soft Tissues?—Critical Considerations Using the Human Cranial Dura Mater as a Representative Morpho-Mechanic Model

The Stress-Strain Data of the Hip Capsule Ligaments Are Gender and Side Independent Suggesting a Smaller Contribution to Passive Stiffness

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