Biomechanical comparison of high hydrostatic pressure versus liquid nitrogen treatment for devitalized bone grafts: a fresh porcine model study

BACKGROUND: Devitalized bone grafting is a widely used reconstructive technique after tumor resection. Conventional devitalization methods, such as autoclaving and irradiation, compromise the biological and mechanical properties of bone. Cryotreatment with liquid nitrogen has been associated with relatively early bone union; however, concerns remain regarding reduced initial mechanical strength and the risk of nonunion. High hydrostatic pressure (HHP) has been proposed as a novel devitalization method that may better preserve bone strength. This study aimed to compare the mechanical properties of fresh porcine bone treated with HHP versus liquid nitrogen. METHODS: Fresh, unfrozen porcine vertebrae and femurs were collected and processed within 72 h to avoid confounding mechanical effects of prior freezing. Trabecular bone cubes (10 mm per side) from the vertebrae underwent compressive testing (n = 10 per group), and cortical bone beams (5 mm wide) from the femurs underwent three-point bending tests (n = 12 per group). Specimens were allocated to three groups: HHP-treated (200 MPa, 10 min), liquid nitrogen-treated (- 196 °C, 20 min), and untreated control. Mechanical testing was performed using a universal testing machine. One-way analysis of variance with Tukey's post hoc test (p < 0.05) was used for statistical analysis. RESULTS: In trabecular bone compression testing, both HHP-treated and liquid nitrogen-treated groups demonstrated lower maximum compressive load at failure than the control group. A significant difference was observed only between the liquid nitrogen-treated and control groups (p = 0.003). The difference between the HHP-treated and control groups was not significant (p = 0.07), and no significant difference was found between the two treatment groups (p = 0.39). In cortical bone three-point bending tests, no significant differences in maximum load at failure were observed among the groups (p = 0.37). CONCLUSIONS: HHP treatment did not significantly compromise mechanical properties compared with the untreated control, whereas liquid nitrogen treatment significantly reduced the maximum compressive load at failure of trabecular bone. These findings suggest that HHP may represent a structurally viable devitalization method for bone grafts, particularly in load-bearing applications.