The determination of ultrasound velocity in the os calcis, thumb and patella during childhood.

Maximising the accumulation of bone tissue during growth and puberty is one of the most important aims in the prevention of osteoporosis. For prevention studies in children it is necessary to develop methods for skeletal status without radiation. Ultrasonic velocity (speed of sound = SOS) has been proposed as an alternative method. Using a new ultrasonic system (Osteoson K4, Minhorst, Germany), we investigated the reproducibility and age-dependency of SOS in several peripheral bones in 218 children and young adults. Intra-observer (day to day) reproducibility: calcaneus CV = 0.64%, patella CV = 1.18% and thumb CV = 0.43% (n = 25). Inter-observer reproducibility: calcaneus CV = 1.1%, patella CV = 2.48% and thumb CV = 0.62% (n = 16). SOS in thumb and patella increased with age and peaked at 20-25 years. SOS in the calcaneus showed no increase after puberty. Studies in bones from pigs show no dependency of SOS from the thickness of analysed cortical or trabecular bone slices. We conclude that the reproducibility of SOS measurements especially in the thumb is comparable with those of radiation methods. The SOS data in growing, healthy children and the independency from bone dimensions provides more evidence that SOS describes the elastic qualities of the bones.