Intraoperative Registration

Intraoperative registration techniques can be classified as manual, semiautomatic, and automatic [85]. Manual registration provides simultaneous visualization of the patient and 

---

Most CIS applications require more than one transformation to link two data sets, and thus have more than one registration problem. For example, in the ROBODOC system, the preoperative plan has to be registered to the intraoperative position of the bone so that the robot tip can machine the desired canal shape in the plan position. To obtain this transformation, we must compute the transformation from the bone coordinate system to the implanted fiducials, then from the fiducials to the robot tip, to the robot coordinate system, and then to the cut volume. The series of mathematical transformations that align one data set with another is called the registration chain. 

Rigid geometric registration between a surface model obtained from preoperative CT and intraoperative surface data on the same anatomy obtained by touching landmarks or collecting sample points with a tracker. This method is widely used in CIS orthopedic systems, such as pedicle screw fixation, total hip and knee replacement, and trauma. 

Here we present several commercially available robots used for surgical tool positioning, which we classify on the basis of the used registration method. The registration defines the geometrical transformation between the preoperative plan and the intraoperative environment in which the task is defined. 

---