Reduction of femoral shaft fractures in vitro by a new developed reduction robot system 'RepoRobo'.

Closed reduction of the long bones is associated with the use of considerable force. This force must be maintained for the reduction maneuver and fixation process. At present, apart from the extension table or the large AO distractor, only rather inadequate reduction aids are available. A solution to this problem is being sought in the form of a robotic system with which precision can be improved and the holding effort reduced. In the research project presented here, a synthetic femur with integrated tensioned mainspring and a 32-A3 type fracture served as a bone reduction model. The fracture was stabilized with a standard AO fixator. A Stäubli robot (model RX130) was converted by appropriate modification so that it could be used for the reduction of femoral shaft fractures in vitro. The robot was equipped with a pneumatic 2-fingered gripper, on which the fingers have been modified so that they can grip the AO fixator clamp. A Force-Feedback-Sensor was inserted between the gripper and the robot to obtain online recordings of the forces and moments in all three axes. With this setup it is possible to achieve precise reduction of the fracture in all planes under visual control.

Development of a robotic navigation and fracture fixation system.

The use of robotics in surgery is nothing new. However, there are areas of surgery, such as in fracture fixation, where robots have yet to be implemented. This paper considers the choice of robot, gripper and ancillary equipment together with navigation systems necessary for their application. Hitherto robots have seen operation in surgery only in cases where relatively low manipulation forces are required. Nothing yet exists with the capability of handling forces in excess of 200 Newton as would be required in the above scenario. Another encumbrance to robots which are already in medical use is the difficulty in programming. Unfortunately most of these robots are programmed by specialists for a particular application. However, there exists a number of robot programming languages, like Unimation VA-LII (recently superceded by Stäubli V+), which do not require specialist knowledge. The application of industrial robots to the "heavier" side of modern surgery is without doubt technically realisable. The remainder of this research project aims to determine exactly which robots and what ancilliary equipment are needed and then to implement them, first on plastic models and later on cadavers. A second phase is expected to deal with type approval and a final third phase with operations on live patients.

Technologies for haptic systems in telemedicine.

The ability to image the elastic properties of tissue is potentially useful in a variety of applications. The field of elastic imaging has grown in response to the potential use of such information in medical diagnosis. Real time ultrasound elastography represents a recent development in determining strain and elasticity distributions. Nevertheless, commonly used imaging techniques rely on the interpretation of two dimensional visual data displayed on a video screen. In reality however, physicians often prefer tactile exploration making the simultaneous portrayal of both video and haptic information most desirable. Since the 1970's many alphanumeric to tactile data conversion methods have been investigated, mainly with the ultimate aim of assisting the blind. More recently, interest has been directed toward the display of pictures on haptically explorable surfaces--Tactile imaging. Such a system would allow surgeons to examine hard sectors contained within soft tissue, and thereby assist in operations held remotely. The expansion of ultrasound elastography to 3D formats would mean the ability to haptically explore regions of the body normally inaccessible to human hands. For three-dimensional imaging the acquisition of sequential tomographic slices using Elastography, combined with image segmentation, enables the reconstruction, quantification and visualisation of tumour volumes. In a collaborative project between four research institutes, the aim is to produce a prototype three dimensional tactile displays comprising electrically switchable micromachined cells, whose mechanical moduli are governed by phase changes experienced by electrorheological and/or magnetorheological fluids. This will be integrated with a sensory ultrasonic elastography in order to present the human fingers with controllable surfaces capable of emulating biological tissue, muscle and bone.