Quantification of reaming debris at the fracture gap of diaphyseal A3 femur fractures after reamed intramedullary nailing and using an intramedullary application system.

BACKGROUND

After reamed nailing in long bones, there is a negligible amount of reaming debris at the fracture gap of A2 and A3 fractures. The aim of this study was to show whether there are differences between reamed nailing and reamed nailing with controlled intramedullary application of reaming debris at the fracture gap with an intramedullary application device.

METHODS

In this trial, 12 human femur specimens were used. On the medullary isthmus, 12 A3 fractures were artificially produced. Afterward, reduction was done by a monocortical external fixator, and closure of the fracture gap was done with a latex finger tip. Intramedullary reaming was performed for up to 10% of the bone cortex. In six femurs, the reaming procedure alone was performed, and in six human femurs, additional controlled application of reaming debris was done. For fixation, an intramedullary plastic implant was used. The region of interest was scanned with the μ-CT 80, and the fracture gap was contoured with digital imaging software. The threshold for the reaming debris was set at 365.6 mgHA/cm³. The analysis of the bone debris located at the fracture gap was measured by percent of debris volume to gap volume. For statistical analysis, the Wilcoxon test was used and a level of significance of p < 0.05 was chosen.

RESULTS

The fracture gap volume ranged from 7 mm³ to 29 mm³ without differences in both the groups. In the group without controlled intramedullary application, there was a median bone volume of 0.37 mm³ found at the fracture gap. In the group with controlled intramedullary application, a median of 2.2 mm³ of bone debris was found. The degree of filling of the fracture gap with bone debris was 2% without additional application and 13% with additional application, using the newly developed application device.

CONCLUSIONS

The results show that reaming debris at the fracture gap without additional application is negligible. When using an intramedullary application device, the amount of reaming debris at the fracture gap can be increased significantly.