A Stepwise Ultrasonic‑Assisted Protocol for High‑Quality Skeletal Preparation from Formalin‑Fixed Cadavers

High-quality human skeletal specimens remain indispensable for anatomical education, surgical training, and forensic science, yet preparation of intact bones from formalin-fixed cadavers remains technically challenging. Formalin-induced protein cross-linking renders soft tissues resistant to removal, while conventional boiling or strong-alkali maceration often results in incomplete cleaning or irreversible damage to fragile bone structures. In this study, we developed and evaluated a novel stepwise protocol specifically designed for skeletal preparation from long-term formalin-fixed, post-dissection cadavers. Thirty adult cadavers fixed in 10% formalin for more than one year were allocated to one experimental group and four control groups employing traditional hot-water maceration or variations of potassium hydroxide–based treatment. The experimental protocol integrates weak-acid pre-soaking, calcium hydroxide–supplemented alkaline maceration, ultrasonic agitation, and anatomy-guided soft-tissue preservation for vulnerable skeletal regions. Outcomes were assessed based on processing efficiency, completeness of soft-tissue removal, and preservation of cortical and delicate bone structures. Compared with all control methods, the experimental protocol consistently achieved rapid and thorough soft-tissue removal while preserving skeletal morphology across all bone types. Control methods demonstrated either incomplete tissue removal, substantial cortical damage, or both. Although the protocol requires operator expertise and access to ultrasonic equipment, it offers a reproducible, scalable, and sustainable approach for high-fidelity skeletal preparation. This method enables effective secondary utilization of dissected formalin-fixed cadavers and provides a practical solution for anatomical education and research in settings where access to fresh cadavers is limited.