The value of the macerated skull as a model used in orthopaedic research

In this study a method was developed to enable the measurement of initial bone displacement in vivo, post-mortem, and in vitro. Speckle interferometry was used as measuring technique. Through the construction of the centres of rotation, the different orthopaedic effects could easily be compared. Also the magnitude of the bone displacement could be calculated. The initial post-mortem displacement of the maxilla corresponds very well with the initial in vivo displacement. After maceration and drying of the skull, however, clear differences from the in vivo displacement were found. The orthopaedic effects on a macerated skull can be manipulated considerably by changing, for instance, the degree of humidity. Only a limited number of skulls was examined in these experiments and probably still other variables exert an influence on the bone displacement in the macerated skull. Nevertheless, it is certain now that the dry skull cannot reliably be used as a model to simulate the initial bone displacement in vivo. The experimental set-up of this study will be used in the future to evaluate the effect of environmental factors (humidity, temperature, etc.) in an attempt to improve the value of the skull as a model for orthopaedic research. Moreover, this technique permits investigation of the link between initial displacements in vivo and longitudinal changes.