IDENTIFICATION AND LOCALIZATION OF METAL IMPLANTS BY ULTRASOUND IN THE FIELD OF TRAUMATOLOGY - AN EXPERIMENTAL-STUDY

The aim of the present study was to establish the typical ultrasound ( US) patterns of metal implants used for internal fracture fixation, an d consequently to use US for the identification and localisation of su ch implants. We investigated both the visualization of the implants in term of size and shape, material (titanium, steel, biodegradable scre ws) and surface structures, and possible changes in the echo pattern i n relationship to surrounding structures (muscles, body fluid), proxim ity to bone, and changes in the angle of insonation. For this purpose ultrasonography was performed on artificial and isolated cadaver bones in a water bath, as well as on cadaver limbs following prior implanta tion of screws, plates, K-wires and cerclage wires. We found that, fro m a certain size upwards, metal implants can be easily localised on th e basis of typical artefacts (resonance artefact, comet-tail artefact) . US is thus most suitable for localisation of metal implants. The spa tial and anatomical relationship to bony structures, joints, tendons, muscles and blood vessels can be determined with a high degree of accu racy.