Measurement of the stiffness of fracture callus in vivo. A theoretical study

The purpose of this study is to analyse the relationship between the rigidity of a fracture callus and the percentage of healing. Different cases were investigated: 1. (1) comparing the fractured bone with a beam submitted to tension; 2. (2) comparing the fractured bone with a beam submitted to bending; 3. (3) when the deformation of a centromedullary nail, submitted to bending is recorded by a strain gage cemented at the level of the fracture; 4. (4) in the same conditions as previously, when the fracture is maintained by a plate, and 5. (5) when the strain gage is cemented on the fixation beam of an osteotaxis. In all the cases, the relationship has an hyperbolic pattern.