Elastic properties of Thiel‐embalmed human ankle tendon and ligament

Abstract

Thiel embalming is recommended as an alternative to formalin-based embalming because it preserves tissue elasticity, color, and flexibility in the long term, with low infection and toxicity risk. The degree to which Thiel embalming preserves elasticity has so far been assessed mainly by subjective scoring, with little quantitative verification. The aim of this study is to quantify the effect of Thiel embalming on the elastic properties of human ankle tendons and ligament. Biomechanical tensile tests were carried out on six Thiel-embalmed samples each of the peroneus longus, peroneus brevis, and calcaneal tendons, and the calcaneofibular ligament, with strain rates of 0.25%s(-1), 2%s(-1), and 8%s(-1). The stress-strain relationship was calculated from the force-extension response with cross-sectional area and gauge length. Young's modulus was determined from the stress-strain curve. The results showed that the tendon and ligament elasticity were lower after Thiel embalming than the literature values for fresh nonembalmed tendons and ligament. The biomechanical tensile test showed that the measured elasticity of Thiel-embalmed tendons and ligaments increased with the strain rate. The Thiel embalming method is useful for preserving human ankle tendons and ligaments for anatomy and surgery teaching and research, but users need to be aware of its softening effects. The method retains the mechanical strain rate effect on tendons and ligament.

Walter Thiel's Embalming Method: Review of Solutions and Applications in Different Fields of Biomedical Research

“…To prove what Thiel said about the good flexibility and plasticity preservation in organs and tissues, several authors studied the biomechanical properties. Liao et al (2015) studied the elastic properties of the ankle tendons and ligaments to evaluate the deformation rates. The results of this study of biomechanical traction demonstrated that the elasticity of Thiel-embalmed tendons and ligaments increases with the rate of deformation.…”

“…The use of conventional embalming techniques with formalin presents an important limitation in terms of tissue texture (stiffer), odor, durability, as well as the impossibility of creating the pneumoperitoneum in formalin-embalmed cadavers, and thus the difficulty of undertaking endoscopic surgical techniques (Healey et al, 2015;Feigl et al, 2013b;Liao et al). In this review, a large amount of literature was found that proposes the use of the Thiel-embalmed cadaver as a simulator to replicate surgical techniques and the training of surgeons.…”

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”

“…However, their conclusions differ to large extent, which might cause some confusion for the readership and raises issues surrounding standardized testing of soft tissue material in anatomy and biomechanical research. While Liao et al (2015) reported decreased elasticity in six Thiel-fixed calcaneal tendons when compared with existing data on native ones (Louis-Ugbo et al, 2004;Verstraete et al, 2015) showed an increased Young's modulus in Thiel-embalmed calcaneal tendons compared with fresh ones from matched pairs. Both studies do have an apparent overlap in their data with loading rate-dependent properties ranging between 62.23 6 18.96 to 272.82 6 86.61 MPa (0.25%/s to 8%/s) (Liao et al, 2015) and 152.25 6 50.68 MPa (static loading with no further information given) (Verstraete et al, 2015), though the strains at which the material properties were computed were different.…”

“…While Liao et al (2015) reported decreased elasticity in six Thiel-fixed calcaneal tendons when compared with existing data on native ones (Louis-Ugbo et al, 2004;Verstraete et al, 2015) showed an increased Young's modulus in Thiel-embalmed calcaneal tendons compared with fresh ones from matched pairs. Both studies do have an apparent overlap in their data with loading rate-dependent properties ranging between 62.23 6 18.96 to 272.82 6 86.61 MPa (0.25%/s to 8%/s) (Liao et al, 2015) and 152.25 6 50.68 MPa (static loading with no further information given) (Verstraete et al, 2015), though the strains at which the material properties were computed were different. Both studies also gave some details on the duration of the samples in the Thiel fixatives, donors' age, loading scenario, calculation of the cross section and the approach for computing the stress-strain properties.…”

“…With great interest we read the articles of Liao et al (2015) and of Verstraete et al (2015), both dealing with the effects of Thiel fixation (Thiel, 1992) on the mechanical properties of the human calcaneus tendon. Given the need for anatomically preserved tissues to avoid autolysis and bacterial or fungal contamination, the Thiel fixation undoubtedly provides an option with lifelike haptic and visual properties for student and postgraduate training (Thiel, 1992;Balta et al, 2015;Hammer et al, 2015).…”