3-D COSMOS: a new 3-D model based computerised operation simulation and navigation system.

A new three-dimensional (3-D) model based system for preoperative planning, simulating the operation and transfer of the operation from 3-D model to patient (navigation) is to be introduced. A computer controlled digitizer with specially designed software enables 3-D measurement and symmetry analysis on the 3-D model with a precision better than 0.01 mm (SD: 0.05 mm, range: -0.2 to +0.04 mm). Translocations of the jaws during simulation are electronically registered with 6D-position sensors and displayed graphically and numerically on the PC screen (measurement accuracy 0.01 mm, 0.002 degrees). A precise transfer of positional data from the model to the patient in the operating theater is necessary if 3-D model operations are to be made. The position transfer (navigation) system to be introduced depends on a neurosurgical headframe on the patient, enabling an easy and three-dimensionally precise transfer of the planned jaw position to the patient. The three-dimensional precision of the positional transfer is 0.05 mm (SD: 0.144 mm, range: -0.36 to +0.69 mm). This new method allows for the first time exact three-dimensional simulation of operation and precise transfer to the patient. Especially in the case of asymmetric malformation and complex dysgnathia, the new method facilitates optimal symmetric and aesthetic results.