Bone strain gage data and theoretical models of functional adaptation.

The in vivo implantation of strain gages on the surface of bones has proven to be a very useful technique for studying the relationship between in vivo loading and bone growth and adaptation. However, data from such experiments have yet to be well incorporated within the context of theoretical models of bone adaptation. Methods for analyzing bone rosette strain gage recordings within the framework of strain energy density-based computational modeling/remodeling theories are presented. A new strain energy density based parameter, energy equivalent strain, is proposed as a single scalar measure of cyclic strain magnitudes and the concept of a daily strain stimulus is also introduced. As an illustrative example, the approach is applied to analyze previously reported in vivo data from the anteromedial human tibia (Lanyon et al., 1975, Acta orthop. Scand. 46, 256-268).