Development and comparative efficacy of tissue restoration formulations for embalmed cadavers using lactic acid at varying concentrations and durations

Abstract

Cadaveric fixation with high-concentration formalin causes extensive protein cross-linking, leading to progressive muscle stiffness and limiting repeated use for anatomy and surgical training. This study therefore aimed to develop and evaluate the efficacy of a tissue-softening solution composed of lactic acid combined with phenol, in 6 formulations (lactic acid concentrations of 0.25, 0.50, and 1.00 percent, combined with immersion durations of 12 and 24 hours), using Sartorius muscle specimens from the cadavers, totaling 30 samples (5 samples per group). Outcomes were evaluated using a Texture Analyzer, a colorimeter (CIE L *a* b*), physical measurements, and examination under a microscope. Statistical analysis was performed using Two-way repeated ANOVA and Šídák's test, with a significance level of p < 0.05. Springiness and cohesiveness increased while resilience decreased in all groups, suggesting improved elastic behavior of the treated muscle. Hardness showed inconsistent changes among formulations without statistically significant differences, and color remained unchanged. Specimen length and thickness increased while circumference decreased in all groups; weight varied by formulation. Microscopic images showed a glossier muscle surface and decreased interfiber spaces after treatment. This restoration solution restored softness, moisture, and elasticity to previously used formalin-fixed muscle tissues and may provide a practical approach for restoring and reusing biological specimens in anatomy education and surgical skills training, thereby reducing preparation costs and improving resource efficiency.