Mini-navigator: a new system for navigated deformity corrections.

BACKGROUND

The purpose of this study is to present a new navigation device for deformity correction surgery and to evaluate its accuracy compared with a conventional electromagnetic navigation system in tracking the orientation of synthetic bony fragments.

METHODS

This system consists of three sensors and software which can be installed on any personal computer. One sensor is mounted about 1 m above the other sensors. The remaining two sensors are fixed to the bone fragments using Schanz screws. Data from all three sensors are computed using the software to estimate the change in position of the sensors. For the first part of the study 118 planned one and two plane deformities in 5° increments were created. For the second part of the study complex random 3-dimensional deformities were created (300 valid measurements).

RESULTS

The mean absolute differences between measurements of the electromagnetic and mini-navigator were 1.8 ± 1.9° in the coronal, 1.1 ± 1.1° in the sagittal and 0.8 ± 0.7° in the transverse plane. Absolute differences between mini-navigator and Fastrak measurements were significantly affected by the magnitude of the deformity (P < 0.0001) with better accuracy for lower deformities.

CONCLUSIONS

We believe that this new technology is appealing, because of its high accuracy and lower planned costs compared with conventional navigation devices.