Biomechanical Effects of Unidirectional Expansion Using Anisotropic Expanders in Horse Skin Tissue.

The research investigates how the use of tissue expanders in specific areas of a horse’s body has varying degrees of effect on biomechanical properties of the skin. While the skin from the shoulder area becomes more elastic when expanded, the skin from the forehead and the lower forelimb becomes stiffer.

Objective and Methodology

• The study aimed to explore the mechanical properties of horse skin when stretched using anisotropic tissue expanders in distinct areas (forehead, right shoulder, and lower part of the right forelimb). Anisotropic tissue expanders are implants that expand skin tissue in one direction.
• This experiment involved six horses, whose skin was expanded over a period of 14 days. Skin samples were then gathered from the expanded areas as well from normal, unexpanded areas as controls.

Testing and Results

• The harvested skin samples were subjected to a uniaxial tension test, which measures the elasticity of the skin by applyingforce until certain point called the breaking point. The skin’s elasticity (‘EM’ – Elastic Modulus), the maximum force it could withstand (‘MF’), the maximum stress (‘MSs’), and the maximum strain (‘MSr’) were evaluated.
• The findings showed that the expanded skin from the shoulder had higher EM, MSs, MSr and MF compared to the normal skin and expanded skin from the forehead and forelimb. This implies that the expanded skin from the shoulder was more elastic.
• Statistical analysis revealed a significantly higher MSs for the expanded shoulder skin compared to the lower forelimb skin, indicating more resistance to breaking under pressure. However, the EM, MSr, and MF did not significantly vary across the different areas.
• While the study showed the location had a significant effect on EM and MSs, no notable influence was attributed to the individual horse or the expanded area in relation to unexpanded skin across the different locations.

Conclusion

• In summary, the results indicated that the expanders made the skin at the shoulder more elastic, while the forehead and lower right forelimb skin was deemed stiffer. Therefore, the study suggests that the precise location of skin where expanders are used might impact the success of reconstructive surgeries, as the resultant biomechanical properties of the skin vary.