IN-VIVO INVESTIGATION OF MATERIAL QUALITY OF BONE TISSUE BY MEASURINGAPPARENT PHALANGEAL ULTRASOUND TRANSMISSION VELOCITY

The square of ultrasound transmission velocity in a material is relate d to the modulus of elasticity, which is known to be an indicator of s tability in bone. The aim of our study was to use ultrasound transmiss ion velocity to obtain information about the material properties of bo ne tissue, keeping other factors possibly influencing ultrasound trans mission as constant as possible. Apparent phalangeal ultrasound transm ission velocity (APU) measured in 54 isolated, fresh pig phalanges was shown to be independent of bone mineral density (BMD) measured by SPA . Fastest sound transmission led exclusively through cortical bone so that intertrabecular connectivity in spongious bone could not influenc e the result. In humans APU was measured in the mediolateral direction at the midphalanx of the middle finger. In 53 healthy subjects (15 - 81 years old; 27 women, 26 men), there was a decrease of APU with age (r = -0.30, p < 0.05). Further, when comparing the results of both han ds intraindividually almost identical values indicated constant intrai ndividual architecture of bone at this location. There was no evidence for a relation of APU to physical load comparing dominant and nondomi nant hand and relating the results to subjectively estimated physical load. In a second group of 43 perimenopausal women (47 - 60 years old) , APU, which again decreased with age (r = -0.33, p < 0.05), was found not to be correlated to BMD measured by SPA at the distal forearm (co rtical bone). In a third group of 40 women (17 - 78 years old), APU ag ain decreased with age (r = -0.60, p < 0.001) and was not correlated t o BMD measured by SPA at the midphalanx of the middle finger, i.e. the same measuring location as APU. We conclude that this method provides information about the modulus of elasticity of bone with negligible i nfluence of bone mineral density. Our results indicate that there is a deterioration of bone material quality with age independent of decrea sing bone mineral density.