Ultrasonic transmission velocity and single photon absorptiometric measurement of metacarpal bone strength: an in vitro study in the horse.

Ten pairs of third metacarpal bones from Thoroughbred horses aged two to 12 years were used to estimate bone strength. Measurements of transverse cortical ultrasound velocity, cortical cross sectional area and bone mineral content were made using ultrasonic transmission velocity and single photon absorptiometry. These data were used to determine bone mineral density, compact bone density and modulus of elasticity. The results were compared with those measured by direct means or chemical analysis and satisfactory correlations were obtained between estimated and measured values. Single photon absorptiometry was found to be more accurate than dual photon absorptiometry. The estimated modulus of elasticity in the transverse direction correlated well with the measured longitudinal value obtained by compression testing. This investigation confirmed the value and precision of using a combined ultrasonic and photon absorptiometric technique for non-invasive measurement of bone strength.