Use of image intensification can be used to check coronal plane alignment of the temporary fixation k-wire or first periarticular screw before final fixation of the articular portion is conducted.

The image force acting on the screw dislocation is then calculated.

The algorithm to perceive the image and get the parameters of screw in screw sampler based on CCD camera is presented. How to extract the edge of screw image is discussed with emphasis.