At Erlangen University Hospital, the first commercially available operating robot in Europe recently went into clinical service after a series of e extensive bench-tests at the hospital's emergency surgery unit. The new high-precision robot has been developed in Germany and was showcased at the MEDICA 98 Fair, last November in Düsseldorf. During a direct live transmission from Erlangen University Clinic, the Medica Fair visitors were able to witness how the device's sleight-of-hand outperformed the accuracy of the surgeon's touch in a complex replacement hip operation. The robot will assist physicians in replacement interventions of both hip and knee joint implants.
Up till now, robot-controlled hip replacement surgery constituted an exclusively American business but with the arrival of the new robot, the growing need for high-precision operation tools in Europe seems to be filled in. In Germany alone, the number of artificial hip joints inserted each year amounts to 130.000, whereas the potential for replacement with artificial kneecaps forms about 65.000 cases.
The surgeon can equally use the robot in the pre-operative planning stage. First of all, images of the femur are produced by means of X-ray computed tomography (CT). Subsequently, the visual data is being transformed into a three-dimensional shaft. This enables the physician to perform the planning of the surgical intervention on screen. From an electronic catalogue, a set of standard replacement joints are selected and superimposed on the virtual femur shaft in order to determine the ideal fitting one.
Once the simulated operation data has been inserted into the robot, the real implant procedure is started with the robot drilling into the femur. The rate of success is extremely high with no less than 95 percent of the cement-free standard prostheses comfortably placed on the base bone contours by the robot. Traditional hip replacement interventions in which the cavities are hand-fraised by the surgeon, only show a percentage of 40 prostheses that are properly installed.
The problem with hip joint implants consists in the fact that one out of three manually replaced joints is loosening within ten years, which forms a rather painful experience for the patient. Moreover, he will be forced to undergo a second revising operation. The designers of the robot anticipate that the new device greatly will reduce the number of dislocation incidences but only time will tell.
In any case, the robot has already proven its use in reproducible, lasting and high-quality hip prosthesis implantation. Soon, surgeons will start to rely on its services in the replacement of kneecaps. In the spring of 1999, the robot will assist surgeons for the first time with the insertion of new crucial knee ligaments, a type of operation that is performed about 100.000 times every year in Germany. For more details on artificial hip joint implants, we refer to the VMW article on the HipNav system in the August 1998 issue.