Steps towards computer assisted locking of intramedullary nails

摘要

A computer based system is described to assist distal locking of intramedullary nails. Radiographic images of distal end of bone and nail are captured from an image intensifier. The image of the hole in the nail is modelled within the computer. Key parameters are extracted and manipulated to generate the angular displacements necessary to permit accurate drill alignment with the axis of target hole and thus insertion of locking screw. The method requires accurate repositioning of the image intensifier and instructions for this are produced. The technique reduces radiation exposure for both patient and operating team. Trials are in progress to validate the modelling and positioning concepts. The first step processes the image and using a mathematicalmodel predicts the angular correction of the X-ray beam to achieve the concentric circles image. In the second step the image intensifier is adjusted under computer guidance so that the concentric circle image is obtained. Repeat of these two steps is sometimes necessary. The last step involves a robot arm to manipulate a drill guide so that the surgeon can accurately drill along the axis of the hole. Images of the guide from the intensifier confirm its correct position. The first two steps are now elaborated upon. thfAOB