Abstract
Introduction
The fracture healing outcome is often evaluated via ex vivo testing of the fracture callus. However, there is only a small time window, where the callus stiffness is significantly different, i.e. a delayed fracture healing might be undetected if the time point of sacrifice is improper. The aim of this study was to develop an in vivo monitoring concept, which allows determining the fracture callus stiffness in vivo over the whole healing time in rats.
Hypothesis
The fracture callus stiffness can be monitored by measuring the deformation of the external fixation device during gait analysis at several healing time points.
Materials & Methods
The right femurs of sixteen wistar rats were osteotomized and stabilized with an external fixation device (stiffness 119 N/mm or 32 N/mm). The fixator body was instrumented with a stain gauge to measure the deformation. Gait analysis was performed once per week in a gait wheel equipped with a ground reaction force measuring device.
Results
The deformation of the fixation devices decreased over the healing time indicating an increase of the callus stiffness. The flexible fixated group showed a later increase of the callus stiffness indicating a delay in fracture healing.
Discussion & Conclusion
Measuring the deformation of the fixator and gait analysis provides a powerful tool to monitor the fracture healing process in rats. With this, it is possible to detect a delayed fracture healing process more reliable than with ex vivo analyses.
