[A new computer-controlled device for stress images of the upper ankle joint]

A new apparatus has been developed for stress roentgenograms of the ankle joint to demonstrate rupture of the fibular collateral ligaments possible. The disadvantages of well-known techniques, such as manual application of stress and the use of holding devices are eliminated. The inversion stress is applied by a foot support driven by an electric motor. A microcomputer controls the force of inversion in dependence on reactive muscle splinting; i.e. the apparatus simulates the application of the inversion force by a physician acting according to feeling. In contrast to the radiography technique with manual holding, the patient is not able to press the foot against the inversion force if a pain-reflexive muscle contraction occurs. Other holding devices generate the inversion force with a threaded shank or traction weight; with the new device the patient's discomfort lasts only 2 s. In the last 5 years the new holding device has shown its reliability in about 1500 examinations.