Biomechanical investigation of the effect of high hydrostatic pressure treatment on the mechanical properties of human bone.

Several methods are available for reconstruction of bone defects due to malignant tumors. To extracorporally devitalize resected tumor-bearing bone segments two methods, that is, extracorporal irradiation or autoclaving, are available up to now. However, both methods have substantial disadvantages like decrease of bone's mechanical strength. To develop an alternative method for tumor inactivation in skeletal segments, high hydrostatic pressure (HHP) was applied. Previous investigations have shown that human normal and tumor cell lines as well as tumor-afflicted human bone specimens were irreversibly damaged at 350 MPa when subjected to HHP. This study was aimed to examine the alterations of biomechanical properties of human bone after exposure to HHP. Trabecular and cortical bone specimens were harvested from six pair of fresh-frozen human cadaveric femora. The bone specimens from one side were exposed to different pressure values of 300 or 600 MPa over 10 min. Bone samples from the contralateral sites were used as untreated controls. Biomechanical properties were investigated by a quasi-static compression test for trabecular specimens and by a quasi-static four-point bending test for cortical specimens, respectively. Biomechanical properties of the cortical and trabecular bone did not decrease after exposure to 300 MPa regarding the testing parameters Young's modulus and ultimate strength (200.7 +/- 38.7 MPa for HHP treated cortical bone versus 186.5 +/- 34.3 MPa for the untreated control group). After pressure treatment at 600 MPa Young's modulus and ultimate strength respectively remained almost unchanged in trabecular bone and were reduced about 15% in cortical bone (p < 0.001 and p =0.002, respectively). We anticipate that in orthopedic surgery HHP can serve as a novel, promising methodical approach for tumor cell inactivation, which occurs at pressure levels of about 300 MPa. Thereby immediate reimplantation of treated bone segments by preservation of the essential biomechanical properties of bone could become possible. Even after HHP treatment at 600 MPa the strength of bone only decreases up to 15%.