Spinal biomechanical properties are significantly altered with a novel embalming method

In vitro tests on the biomechanical properties of human spines are often performed using fresh frozen specimens. However, this carries the risk of pathogen transfer from specimen to the worker and the specimens can only be used for a limited amount of time. Human spinal specimens embalmed with formaldehyde carry an almost absent risk of transfer of pathogens and can be stored and used for a long time, but the tissue properties are strongly affected making this method inapplicable for biomechanical testing. In this study, a new embalming technique called Fix for Life (F4L), which claims to preserve the tissue properties, was tested. The range of motion (ROM) and stiffness of six fresh human spinal specimens was measured using a spinal motion simulator before and after F4L embalming. After F4L embalming, spinal stiffness increased in flexion-extension by 230%, in lateral bending by 284% and in axial rotation by 271%. ROM decreased by 46% in flexion-extension, 56% in lateral bending and 54% in axial rotation. In conclusion, based on this study, F4L does not maintain physiological spinal biomechanical properties, and we propose that this method should not be used for biomechanical studies. Nevertheless, the method may be an alternative to formaldehyde fixation in situations such as training and education because the effect on spinal biomechanics is less detrimental than formaldehyde and tissue color is maintained.