| Summary: | The development of a measuring device and technique is presented to measure objectively the healing process in distal radial fractures treated with an external fixator. External fixation is advocated in stabilization of unstable fractures of the distal radius to allow a rapid and better patient recovery. Removal of the external fixator too early can result in risk of refracture or late collapse of the fracture. The measuring device developed here is used to calculate the rigidity of the new callus; this quantitative parameter can contribute to the surgeon’s decision to remove the frame. Bone structure and bone fractures are examined from a mechanical and biological perspective. Fracture treatments and healing patterns are presented with particular attention to external fixators and the environmental fracture conditions imposed by these frames. Previous studies on fracture healing (for tibial and femoral fractures) have been considered during the development of the measuring device. A fracture model has been created and used to verify the reliability of the device in laboratory testing. In-vivo testing has been performed to improve the performance of the device and protocol for using it; specifically, to produce an instrument that can be adapted to suit any external fixator geometry met on patients. A pilot study was subsequently organised and conducted to verify the usefulness and reliability of the device under clinical conditions. In order to compare directly the results from different patients, the influence of various external fixator geometries has been investigated, by a finite element (FE) analysis. The FE analysis has been validated against laboratory testing with the fracture model. Combining measurements from the device and data from the computational model (from the FE analysis), the callus rigidity is determined for patients involved in the pilot study. The trend of the calculated callus rigidity is discussed and the results are compared with the conventional clinical methods to assess fracture healing.
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