Prof. Ph. Cinquin, Ph.D.,M.D.
Université Joseph Fourier Grenoble, France
Institut Albert Bonniot
Computer Assisted Planning and Execution with Individual Templates
Project No.: HC-1026-HC
(Project term: 1996-1999)
The recent developments in the area of computer assisted surgery offer different technological solutions to translate the high geometric accuracy of the preoperative imaging and planning into a precise intraoperative execution /Taylor96/. But the analysis of tasksequences of the surgical team in the course of typical conventional orthopedicinterventions shows, that the overall time spent in activities with some relevance ofexact spatial orientation, only take about 10-15% of the total operating time. Additional time needed for the interaction with complex technical systems and for additionalregistration of bone structures can be tolerated only to a very limited amount. Problems also arise due to the overall costs of the sensor- or robot-based systems, the spatialarrangement of displays, sensors and robot systems within the operating room andmismatches regarding aspects of cognition and manual control.
Development of a low-cost and easy-to-use technical solution forCT-image based 3D-planning and execution of work on bone structures.
In orthopedic surgery standard templates are very familiar technical means for the guidance of tools. However, in general the spatial position ofthese toolguides in relation to the bone structure cannot be exactly defined and reproduced according to the individual preoperative planning.
Individual templates are customized on the base of 3D-reconstructions of the bone structures extractedfrom CT-image data and depending on the individual preoperative surgical planning. For the preoperative customization of these mechanical toolguides, a desktop computer controlledmilling device is used as a "3D-printer" to automatically mould the shape ofsmall reference areas of the bone surface into the body of the template. Thus the plannedposition and orientation of the toolguide in spatial relation to bone is stored physicallyand can be reproduced intraoperatively by simply putting this individual template with itscustomized contactface formclosed on bone without the need of any additionalintraoperative computerized equipment or waste of time. Mechanical tool-guides for drills,saws, chisels or milling tools are adaptable or integrated into these individual templatesfor different types of interventions. This approach has been demonstrated for differentapplications.