[Ultrasound imaging and localization of metal implants. A clinical study]

In a first experimental study we investigated the visualisation of metal implants in reference to dimension, shape, material (titanium, steel, biodegradable screws) and surface structures and an eventual change of the echo pattern in correlation to the surrounding structures, the vicinity to bone and the change of the sound angle. For this purpose ultrasound investigation was performed in artificial and cadaver bones and in cadaver limbs after implantation of screws, plates, K-wires and cerclage wires. We found that metal implants of a certain dimension can be localised by typical artefacts (resonance artefact, comet tile artefact). In the following clinical study we investigated the value of ultrasound in finding and localisation of implants after osteosynthesis. In patients with 25 locking femur nailing, 30 locking tibia nailing, 30 osteosynthesis done by screws and plating, metal was easily localised by typical artefacts. Ultrasound examination gave the possibility to define the number of screws, the localisation to surrounding tissue, loosening of screws and eventual as sociated inflammatory tissue swelling (bursitis, tendovaginitis).