The assessment of in vivo bone condition in humans by impact response measurement.

Transverse impact tests were conducted on the lower legs of 30 human volunteers and on 18 embalmed human tibiae. The impact was produced by an instrumented hammer and the response was monitored by an accelerometer. The apparent flexural wave velocity, measured from the force and acceleration records, showed significant negative correlations with the ages of both the male and female volunteer groups. The decrease in the velocity with increasing age was more pronounced in the female group. Two patients with bone diseases also manifested a much lower wave velocity compared to that from a normal person of similar age. Results of in vitro impact tests on human tibiae also showed that the wave velocity had: (1) a significant positive correlation with the mass/unit length of bone and (2) a significant negative correlation with the degree of osteoporosis in the bones.