Augmented Reality for Fluoroscopy-based Navigation

		Augmented reality navigation system for total hip replacement (THR) surgeries C-arm based augmented reality navigation of plates for reduction of long bone fractures

A generalized framework for surgical implants and instruments into our Open Inventor based modules has been built. Software was developed for the conversion of CAD drawings and inclusion of 3D volumetric datasets into our framework. Based on this framework an AO/ASIF foundation grant was funded for a database with all major Synthes^® trauma implants and instruments. The framework was connected to this database to achieve full 3D virtual planning and surgery.

On-the-fly computation and visualization of X-ray free fluoroscopic image updates was another focus of this subproject. A prototype C-arm navigation system was designed to incorporate X-ray free image updates and the interactive use of a Synthes^® trauma implant, the LISS^® plate, a long bone fracture reduction, and a fixation device system. With the help of the virtual cylinders from different X-rays, a bone structure of similar shape and volume was created. The reduction process can be checked without continuous radiation.

Moreover, the implants, including the plates, screws and instruments are compared three-dimensionally to virtual X-rays, realistically adjusted and represented in real-time. The insertion of the plate and the fixation with screws, including the drilling process and linear measurement, are precisely navigated in a 3D virtual world. This system was successfully tested in the laboratory setting. The system was then further enhanced to semi-automatically generate the virtual cylinder scene based on gradient vector field based segmentation of the long bones. Several tibial long fracture cases have been successfully treated with our system.

Also, research in C-arm based precision placement of acetabular components during total hip replacement (THR) was performed (this work was awarded the HAP Paul award from the International Society of Technology in Arthroplasty). The THR system was clinically evaluated and an accuracy of better than 5 degrees inclination and 6 degrees anteversion was achieved under clinical conditions, which implies that there is no significant difference in performance from established CT-based navigation methods. The work has been adapted by our partner Medivision/Praxim^® into a clinical module that is in routine use.