[Ultrasonic evaluation of the bone condition. III. Differentiation of the leg echograph].

The echogram from bones in vivo or in model trials consists of the echoes of bones and soft tissues. Under certain conditions, the fore part of this echogram (total echogram) consists of bone echoes only, the intermediate part of echoes from bone and soft tissue with perhaps different amplitudes, whereas the hind part contains only soft tissue echoes. When frequency and distance of the sound head are too high the fore part might be absent, that is when the distance of the sound head becomes larger than 60 mm at a frequency of 1 MHz and a sound head diameter of 30 mm. The amplitude of soft tissue echoes in the intermediate part of the total echogram at greater distances can be higher than the amplitudes of the bone echoes. A definite valuation of these bone echoes by electronic suppression of the total echogram is impossible in that case. For these reasons, controlling the course of fracture healing by help of conventional ultrasonic devices with a frequency of 1 MHz is more difficult than supposed hitherto.